Answers to Automation

This is the final part of the “Automation, Education and Work” talk.

Part 1 of this talk was introduced with the following:

There is a proliferation of articles in the media about how the accelerating technology of artificial intelligence and robots will change the world of work radically in the next 30 years. “47% of current jobs are under threat”. “Self-driving vehicles will put millions of truck drivers out of work”. “We are seeing a hollowing out of middle-income jobs.”

Some say this Luddite fear is unwarranted. “Just because we can’t imagine what new jobs will come along doesn’t mean the next generation won’t”. “We just need to educate everyone for the future knowledge economy.”

Others say “This time it’s different”. “We cannot compete with the robots”. “Maybe we need to tax the robots and have Universal Basic Income?”

In this final part of the talk, I try to formulate responses to these statements. I start with…

“Is there technological unemployment?”

For those in the world of work, life is so busy. We may well say:

New technology has come along but we still work as hard as ever!

So, if new technology hasn’t created unemployment so far, why should it this time?

But new technology has created unemployment previously: we forget the workload of our forefathers. They worked longer working weeks and typically died not long after retiring, if they even got to retire at all. The number of hours we get to do things outside work for every hour spend we spend working has gone up dramatically. The unemployment that has arisen has been spread out among us so that the vast majority of us are part-timers compared to 100 years ago!

The back-of-an-envelope estimations in the table below show how much things have improved.

  1900 2000 ratio%
School leaving age 14 17
Working hours per day 9 7 78%
Working days per week 6 5 83%
Days holidays per year 6 32
Working days per year 306 228
Work hours per year 2,754 1,596 58%
Retirement age 65 60
Age at failing health 65 75
Years of quality retirement 0 15
Waking hours per day 15 16
Leisure hours per working day 3 6
Leisure days per working year 58 136
Leisure hours per leisure day 9 11
Leisure hours per working year 1,440 2,864
Leisure hours per retired year N/A 4,015
Total leisure hours 73,440 183,377 250%
Adult working hours 140,454 68,628 49%
Leisure / work ratio 0.5 2.7 511%

These are just simplistic calculations. They ignore the large amount of leisure time to be had as a child, and what leisure time there is during the years of failing health at the other end of life. You may disagree with some of the numbers but, however you might modify them, the point still stands: the amount of time we need to work to provide us with leisure time has gone down dramatically.

And this does not show the full picture. The greatest single factor of mass unemployment we have seen so far had been the replacement of horse power with mechanical horsepower! In 1900 there was 1 horse for every 4 people in England, with the large majority of horses having an extremely high workload. Nowadays, there just aren’t those working horses around. There is just 1 horse for every 30 people. And they are working much more comfortably – in the leisure industry!

It may seem that we are working as hard as ever and this may well be true within the last few decades but the long-term (e.g. 100-year) trend is downward. See the table below showing the average number of hours worked per year for various industrialised nations over the 20-year period 1976-1996.


Change in annual hours worked for some European countries: Picture credit: OECD.

Note that Anglophone countries have had the least improvements over this time and things have actually gone backwards in the USA. (Also note that figures for inequality show a reduction until about 1980, since when it has increased.)

Country 1976 1996 %
Japan 2,130 1,900 -11%
Spain 2,100 1,810 -14%
USA 1,890 1,950 3%
Australia 1,880 1,870 -1%
UK 1,870 1,730 -7%
France 1,860 1,650 -11%
Italy 1,800 1,560 -13%
Netherlands 1,640 1,370 -16%
Germany 1,640 1,410 -14%

(Table derived from


Change in annual hours worked for mainly Anglosphere countries: Picture credit: OECD.

“This time it is different”

This time is different, just as last time was!

Every time is different; every technological wave that hits us is unique. But some are more pronounced than others. The First Industrial Revolution was truly revolutionary compared with the information revolution that started around the 1950s.

The thing that is different this time is that the revolution affects the cognitive rather than the physical. Yes, human muscle work has been reduced but it was horses rather than us that were fully exposed to the effect of physical-replacement technology. If the new technology starts to do significant brain work, it will not be taking any creatures’ work away other than that of us humans.

Physical automation continues, through the ongoing synthesis of computers and motors – and it is now being enhanced by the addition of Artificial Intelligence (leading to the more intelligent robots and self-driving cars).

But more pronounced (more revolutionary) is the cognitive-only aspect – the arrival of intelligence that is sat inside computers rather than inside robots. Combined with new processes – the near-zero marginal cost business models – this artificial intelligence can be rolled out much more quickly and with much less capital outlay than brigades of robots. Unlike previously, this technology can replace much of the skilled workforce.

 “Just because we can’t imagine what new jobs will come along doesn’t mean the next generation won’t”

There will be many jobs opportunities in the future which we cannot imagine, but many new occupations will never come about: if Artificial Neural Nets can learn to do the current skilled cognitive tasks then they will probably also be able to learn to do many of those new skilled cognitive tasks.

When machines relieved us of physical burdens, we shifted to jobs requiring intelligence (then considered a uniquely human characteristic). Now that machines can relieve us of our intelligent work, we presumably must find refuge in emotional/creative work (now considered a uniquely human characteristic) – but emotional and ‘creative’ work is not completely immune to AI.

Cognitive Physical
deep learning automation (continuing)
quickly slower
skilled mobile
low marginal cost increasingly affordable

“We cannot compete with the robots”

It is true; in many ways, we will not be able to compete with the robots in terms of both capability and productivity. Erik Brynjolfsson and Andrew McAfee say this should not be a problem: we shouldn’t think that we are competing against them but that we are working with them. To provide an example, Garry Kasparov, having lost to Deep Blue, now advocates what is called ‘Advanced Chess’  (also called ‘Centaur Play’), where teams of players play chess against each other and in which some of the team members are computers.  Collectively, they are stronger than any of the individuals. More commonly, one expert in a particular discipline can team up with a machine learning expert with a bit of knowledge in that discipline – plus computer – to create a winning combination.

Most of us will not just be unable to compete with the robots; even if we organize ourselves into teams of humans and computers, we will also be unable to compete with the small set of super-expert winning teams.

And this teamwork between man and machine can be leveraged for a lot of ‘creative’ work.

“Is there a hollowing out?”

I have previously talked about the distinction between technology innovations and process innovations. Now, making a generalisation, we can say that:

  • technology innovations lead to up-skilling plus unemployment whereas
  • process innovations lead to down-skilling.

For example:

  • The introduction of tractor technology led to new skilled jobs involving designing tractors, making tractors, selling tractors and maintaining tractors but this was at the cost of putting many unskilled agricultural labourers out of work.
  • In contrast, the factory production line replaced workers who each had many skills with workers who only needed to perform a single task each.

The net effect is the tendency to create highly-skilled well-paid jobs plus low-paid unskilled jobs at the expense of those skilled jobs in the middle. This is the so-called hollowing out of the labour market.


Maarten Goos and Alan Manning describe the jobs at the top as ‘lovely jobs’ and those at the bottom as ‘lousy jobs’. And within the lousy jobs category there are the ‘three Ds’ that describe the attributes of many of those jobs: dull, dirty, dangerous and demeaning (yes, there are four, but for some reason people only seem to refer to some combination of 3 of these at any one time!)

This hollowing-out seems to be happening now, but might this just be a temporary blip? After all, it hasn’t really happened in the past. Education is part of the answer. Productivity improvements (being able to produce a particular amount of stuff for less work) meant that goods became available at a price affordable to a larger proportion of the population. Cars were no longer the luxury of the elite. So unskilled people (or their children) made unemployed by technology had to be educated to be able to do new skilled jobs. Why won’t this re-educating happen in the future then? It will to some extent. But this time, it will be possible for much of the new skilled work to be done more efficiently and effectively by machines working in collaboration with a relatively small number of the very highly-skilled.

We can always find useful work for the other people to do, including skilled work. More doctors and teachers would be good even when technology has made each doctor and teacher more productive. But where is the money going to come from to pay for those? Will the extraordinarily-rich super-skilled pay it all?

What is the problem with technological unemployment?

There is more to work than just earning money. Imagine if we could automate all jobs away tomorrow, with robots doing everything to run society, leaving us humans to lead lives of full-time leisure. As Voltaire said (in Candide):

“Work distances us from three great ills: boredom, vice, and need”

There is more to work than just satisfying our basic needs of life: eating and drinking, a roof over our heads, and so on. It (potentially) provides us with social interaction, interesting challenges and a feeling of useful contribution to society, commanding respect. And it keeps us preoccupied rather than causing trouble.

M. Keynes, (in ‘Economic Possibilities for our Grandchildren’) re-iterated the problem of boredom:

“It is a fearful problem for the ordinary person, with no special talents, to occupy himself.”

He went on to say:

“We shall endeavour to spread the bread thin on the butter – to make what work there is still to be done to be as widely shared as possible. … a fifteen-hour week may put off the problem for a great while.”

Given the history of employment over the last 40 years, the idea of a 15-hour week is laughable for most of us. But if we could transition to shorter and shorter working weeks gradually (as seen before 1970 and continuing in some countries) it would lead to a culture where people defined themselves according to what they do in their leisure time at least as much as to what they do in their work time. People will have grown up in this new culture and learnt (partly through formal education) how to deal with this. We would realistically hope that there would be an increase in overall well-being as a result.

Seen this way, technological unemployment is not a problem – it is a good thing.

But of course, the problems with technological unemployment are the political issues raised by it:

  • How do we ensure the work gets shared out – to spread the butter thin on the bread (or ‘spread the bread thin on the butter’ as Keynes said) – rather than just allowing those that want to take more than their ‘fair share’ of work to do so?
  • Would we want to, or be able to, restrict the hours of those on significantly-higher wages?
  • We will end up with a new ‘normal’ where the majority are on capped hours on near-minimum wage. How do we cope with a democratic society when the proportion of the working-age population on minimum or near-minimum wage exceeds 50% and becomes the majority?
  • How do we ensure that the diminishing number of highly-paid, highly-skilled workers pay their taxes, when they can so easily move from one economy to another with their wealth?
  • How does the government intervene into the free market of work to make it operate better?

Included in the suite of political problems is how to steer the jobs market so that it is the lousy jobs that are automated away rather than the lovely ones. And note: the demarcation between lovely and lousy jobs may not be as you think. I think we want jobs that are like the office work in that they are clean, safe and interesting compared with their factory predecessors, but office work is generally sedentary (impacting long term health) and often stressful. Light manual, mobile jobs are good jobs.

There will be limits on how far we are able to automate away many of the dull and dirty jobs. We may only be able to get robots to help relieve workers to make them less dull or dirty. It is often said how difficult it is to get a plumber or a cleaner. The same is rarely said about lawyers or accountants. We somehow expect to pay not very much for a cleaner but are resigned to paying high hourly rates for some professions. AI can make big productivity improvements in some of these professions. We perceive white-collar work as higher-status work and therefore deserving of more pay. But in a society in which so many people would be on minimum or near-minimum wage, we will need to get over this prejudice and pay for the dull and dirty tasks at a level more in keeping with their social value.

Universal Basic Income

In a society where work is scarce, large-scale unemployment becomes normal. How do we redistribute wealth from those that are employed to those that are not? Universal Basic Income and Negative Income Tax have been suggested as possible solutions.

With Universal Basic Income, the government provides everyone with a flat-rate benefit with which to pay for life’s basic essentials – food, drink, a shirt on one’s back and a roof over one’s head. Individuals are then able to compete for the work remaining (or engage in other, hopefully useful, activities). Just how basic is basic is open to debate. The value envisaged is typically around $10,000, 10,000€ or £10,000.

Negative Income Tax (NIT) works like this: with normal Income Tax, income up to, say $20,000 is taxed at 0% and income above is taxed at 20%. If the zero-band rate is set instead at -40%, there is a net pay-out as shown below:

  Standard income tax Negative income tax New net
$0 $0 -$4,000 $4,000
$5,000 $0 -$2,000 $7,000
$10,000 $0 $0 $10,000
$15,000 $1,000 $1,000 $14,000
$20,000 $2,000 $2,000 $18,000

People support these various ideas when initially presented with them. But when they are told what tax rates would be needed, they turn against them! It is the political inability to redistribute wealth from some people to others that is the problem. Income tax hikes on the better off have long been considered to be electorally suicidal.

Opinion is divided over UBI. Claimed effects include:

  1. +/- helps to alleviate mental stress (even though often work helps keep you sane)
  2. + avoids the stigma of claiming benefits (although this reduces as a larger and larger proportion of the population receive it)
  3. – counteracting the above, it diverts targeted welfare target to the most needy, dependent on circumstance, to a generalised welfare.
  4. delinking income and work by rewarding people for staying at home is what lies behind social decay.
  5. – undermines incentives to participate in society.
  6. – allows corporate and political leaders to postpone the real discussion about rising inequality, social dislocation and the future of jobs.

Taxing Good and Bad Income

But there is a more fundamental problem here: In a world with technological unemployment, we end up taxing the very thing we want to conserve, namely, good jobs! We need to manage the reduction in work in a controlled way. The market should be steered so that there is a strong incentive to innovate methods of automating the bad jobs (the dull, dirty, demeaning and potentially automatable) and to reduce incentives to innovate methods of automating the good jobs. We could tax work deemed to be good at lower rates (even 0%), but this obviously shifts the burden onto those with ‘bad work’. The latter’s salaries would have to rise to compensate.

Taxing by Other Means

If we are not taxing income, we need to tax by other means. Options include:

  • Wealth (including land and inheritance taxes), and
  • Sales (Use tax) – taxing consumption rather than production.

A significant problem here is that economies are not closed systems:

  • People earning money in one country move that money abroad.
  • People providing a service in one country employ themselves in another.
  • People buy things from another country to avoid paying high sales taxes.
  • (Additionally, people educated in one country go to work in another.)

Note: In what I say above:

  • ‘country’ is any polity, be it a nation, region or super-nation – a political unit in which wealth is redistributed through taxes of one form or another.
  • ‘person’ also includes corporations.

I am considering Corporation Tax as essentially the same as income tax, but it is easier to move this income from country to country because there isn’t any actual body to be physically located anywhere (and they can afford more lawyers than you or I).

Taxing the Robots

If workers aren’t earning the money, who can afford to buy the products? There is the well known (if apocryphal) conversation of Henry Ford II showing off his automated factory line to the labor union leader:

Henry Ford II: “Walther, how are you going to get these robots to pay union dues?”

Walter Reuther: “Henry, how are you going to get these robots to buy your cars?”

So what of taxing the robots, as often asked? Again, we can end up taxing what we want to promote. We want to tax robots that replace good jobs but we don’t want to tax the robots that do the bad.

The popular imagination of future automation is a world of science fiction robots, an imagination reinforced by the media with stock pictures of androids. The reality is not armies of robots scurrying around factory floors but of huge conveyor-belt installations of computer-controlled industrial equipment. And I have argued here that artificial intelligence in software form that can be rolled out quicker than the robots because of its very low marginal cost. Better paid skilled cognitive sedentary jobs will disappear more than commonly expected. Getting robots to do what we think of as simple tasks (such lifting something up and carrying it around an environment evolved for humans) is far more difficult (it is a task comparable to self-driving cars – robots that carry people from one pace to another). So many low paid unskilled physically active light manual jobs will remain for many years.

And besides, many of these light manual jobs are good jobs, useful and sociable. We need to actively manage the taxing of technology to incentivize the market to automate the Lousy jobs away and allow a transition towards Lovely jobs, sharing them out, and with a gradual reduction in the length of the working week.

How can we tax robots when there is a gradual progression of automation from the fixed minimally intelligent toaster (a device that automatically stops toasting without human intervention) up to the general-purpose humanoid robot of science fiction? Clearly we can tax the latter more. Key differentiators are mobility and ability to repurpose. A fixed ‘robo-barista’ (referring back to the Starbucks University un-forecast in Part 2) may still take someone’s job but it cannot be repurposed to, say, vacuum the floor (performed by a different robot) or clear up tables. How do you manage taxing a general-purpose robot that was initially procured to perform a Lousy job when it is repurposed to replace a Lovely job? It may be that the capability of robots is deliberately restricted such that they cannot be re-purposed (also allaying the fears of the ‘singularity’ when the ‘robots taking over’), either through the choice of its owner (to reduce taxes) or by law.

Taxing soft artificial intelligence is more difficult. Robots are physically located in one place and so can be taxed in that place. But Internet services could be served from anywhere.  Perhaps taxing at the customer end is the answer – a sales tax. Previously, I have looked at Freemium and platform models of services. Perhaps we should tax the internet super-highway just as we impose taxes on the old-fashioned highway. Both are means of getting products and services from producers to consumers.

Universal Basic Services

An alternative to UBI is Universal Basic Services (UBS). I think there is potential here to overcome some of UBI’s difficulties, or at least alleviate them by being a complementary partial solution.

A basic service is provided to everyone ‘free at the point of use’, like state education and the much-loved National Health Service in the UK. Seven free public services identified are:

  1. healthcare
  2. education
  3. legal & democracy
  4. shelter
  5. food,
  6. transport,
  7. information

These should go a long way to solving issues such as hunger and homelessness that should have been solved a long time ago in the so-called ‘advanced’ Western societies.

If everything in life is given a monetary value and must be bought in a free market, the amount of money needed just to survive becomes significant.

With UBS, the welfare benefits are de-monetized: the costs are not directly visible to the consumer. The amount of money needed to survive becomes much less. The services still need to be paid for somehow but I believe UBS is more politically acceptable because, when taxpayers baulk at the high rates of tax, they can be challenged with questions:

  • What basic service do you want to deny the poor?
  • Should they be malnourished?
  • Should they be unable to have a warm home?
  • Are they really denied basic medical care?

A major objection to higher welfare benefits is removed: the perception that the ‘feckless poor’ ‘waste their money on’ this, that and the other. They are not given the opportunity to waste ‘our’ money. (Conversely, we no longer have the opportunity to spend ‘our’ money as we choose; the invisible hand of the free market is replaced with the state providing the service, or tendering it out.)


  • There is no stigma about using the services when the majority of the population do.
  • And hopefully, economies of scale reduce the cost per user.

But a more significant advantage of UBS is that it is amenable to the ‘Freemium’ business model (introduced in Part 2): the service can be paid out of our purchases rather than our tax. Income tax doesn’t have to be increased. Users pay for a service and, in doing so, allow others to have a basic version of what they themselves want. There is a direct connection between their needs and the same needs of others:

‘I am hungry; I want to eat; I pay to eat. I understand that other people get hungry too and they want to eat but cannot afford to. I am happy to pay a bit to allow them to have some food that is not as nice/much as mine.’

(Note: This provides a mechanism for the free market to select the service provider, through the choices of the premium user)

Here is a small example (‘un-forecast’): ‘Information’ is one of the basic services above. It is an important contributor to social inclusivity. Access to the internet, via a mobile phone should be universal. Mobile phone operators (private companies) should be mandated to provide a limited number of texts/minutes/Gbytes to and lending a refurbished phone to anyone who requests (with some means to restrict each user to just one servicer provider at a time). It provides the service provider with the opportunity to receive revenue through paid-for (top-up, PAYG) additional benefits and services.

Other services are more difficult to provide freely through a freemium model, but I don’t believe it is  impossible. Consider the provision of food via ‘Universal Basic Canteens’. For efficiency, food is provided ready-prepared (food waste is minimized) rather than as (packaged) raw ingredients (in packaging). They are canteens rather than restaurants: self-service, with limited choice. This also provides the important social benefits of communal eating.

But: it presupposes that those who pay are happy to share the same eating space with those cannot. There is a huge status gradient going from food banks to ‘exclusive restaurants’ (the name says it all). The general population may no longer be prepared to share eating space in canteens in the way that they are generally still prepared to share hospital space. We need a sufficient level of social cohesion.

Owning Less

The introduction of UBS can be seen as part of a wider shift from owning ‘stuff’ oneself to using a service. The overall cost of ownership can be less and resources are used more efficiently (it is more environmentally friendly). Part 2 covered self-driving cars, which allow the completely new business model of what is  called ‘Transportation as a Service’ (TaaS): dramatically reducing personal transportation costs by subscribing to a car service rather than owning a car oneself.

Younger generations, growing up in the internet world, are more used to this concept. They are happy to subscribe to music streaming services such as Spotify in marked contrast with their parents who prefer to own CDs (‘what if the internet disappeared’?). The young are ‘Generation Rent’ in more than one sense of the phrase.

In the song ‘Imagine’, John Lennon asks us to imagine being without countries, wars, religion, greed and hunger and this is all conceivable. But he also asks:

‘Imagine no possessions. I wonder if you can?’

This seems to go too far.

However, a shift from ownership to subscription services makes it possible to imagine a world where we generally own less. I still want my own toothbrush but I am quite happy to live without a (self-mowing) lawnmower. Subscription services take the hassle out of ownership (if it is broke, get the service provider to replace it straight away) and counters the culture that owning material goods intrinsically contributes to happiness.

Un-forecast 5: The Good Gig Economy

Defenders of the gig economy say that it offers workers flexibility to work when they want to. This is at least sometimes true. But mainly, those working in the gig economy are doing so because they need the money and the work offered is the best that they can get. But in a possible future world of Universal Basic Services, less money is needed in order to live a rewarding life. Here I present another un-forecast, in which the gig economy is working better for people…

Three friends in their twenties are working on a musical. They write the script and music using free software on a tablet and practice the performance in their free time whilst working casually in Starbucks. Their uploaded music creates publicity for gigs in their local town and nearby. But they occasionally have a holiday which is a nationwide tour of their music or of their musical. They use their tablets to record a promotional video with the help of free video editing software. Other material is edited with free software. It is all uploaded onto various social media sites.

They rent flats which have secure storage which enables them to sub-let them easily through Airbnb. They do this when touring, staying in similar accommodation. An app allows them to build up an itinerary so that renting and sub-letting more or less cancel each other. A similar Starbucks app gives them the flexibility to shift work to the various places that fit in with their itinerary.

Since so many people would be doing this, there would hardly be any money to be made performing music but they would be able to fulfil their leisure passions and go on long vacations at minimal cost.

The point I am trying to make here is that people can lead lives in this form of the gig economy that have a better work / life balance, providing creative opportunities for whoever wants it and opening up the talent pool for entrepreneurial enterprises far wider than it is today. And this can be achieved with relatively little money sloshing around, through the use of peer to peer and free services. Society would be qualitatively richer as a result.

New activities would arise as a result of this new economy. These activities may create new jobs, but they are more likely to be in the form of providing services to one another rather than in formal employment.

“We just need to educate everyone for the future knowledge economy”

People supposedly say that ‘we just need to educate everyone for the future knowledge economy’ because we need to expand higher-level education so that the unskilled workers for whom ‘the robots are going to take their jobs’ are in a position to do the newly-created jobs. But, as I have said, the AI that might replace the job you have now might also be able to take the job you might have had in the future.

Now, we do need to improve the level of education of the ‘workforce’ but a significant factor here should be that we need people to do more of the current skilled jobs, like doctors (very skilled) for example, so that we can ‘spread the bread thin on the butter’. But this will be expensive (investing heavily in a highly-trained person and not using them for as many hours of the week as possible is obviously less efficient).

In a surprising article called ‘The Skills Delusion’, Adair Turner says there is no point in educating people to perform zero-sum jobs i.e. those that do not increase net human welfare. More people getting university degrees does not mean higher productivity. Students may simply be willing to spend a lot of money on an education to signal to employers that they have high-value skills!

We should be providing the following education:

  • Primary education, including numeracy, literacy and computer literacy, for basic functioning within modern society.
  • Secondary education extending that primary education, providing a broader knowledge of the world around us and allowing individuals to make life choices.
  • Secondary education of general well-being for ‘survival’ in the modern world. This includes having a flexibility and the attitude to adapt and learn. It also includes having entrepreneurial skills to help stimulate an enriching life within the ‘good gig economy’.
  • Secondary education in ‘Data Science’. Older people grew up in a world where knowledge was scarce; people needed skills such as using an index catalogue in a library to find knowledge and people needed the ability to remember that knowledge. Young people have grown up in a world where knowledge is abundant (overwhelmingly so). People now need to know how to handle knowledge – how to sift out information from an internet of varying quality (including ‘fake news’).
  • Tertiary education in ‘Data Science’ and other STEM (Science, Technology, Engineering and Mathematics) subjects (including Computer Science) to provide the technology that means we don’t have to work so much.
  • Tertiary education in other (existing) subjects for skilled work, such as for doctors, as already mentioned.
  • And then: tertiary education in other areas, not for any direct benefit but as part of an education for life outside of employment, enriching one’s quality of life and thereby enriching the culture in society.

STEM Graduates

The countries with most STEM (Science, Technology, Engineering and Mathematics) graduates are going to be the ones that will be able to capitalise on this new technology. Which countries are these?

World Economic Forum data from 2016 and OECD projections for 2030 is tabulated below. Both the  STEM graduate numbers and total country populations are in thousands. What is being measured is different between the two years but the data highlights the relative strength in numbers of STEM in China, Russia, Iran, Saudi Arabia and South Korea compared with USA, the EU and Japan.

Obviously, the quality of those graduating varies from country to country.
Migration is a significant factor. Currently, 16% of US scientists come from outside the USA whereas only 3% of EU scientists come from non-EU countries (source: OBHE, 2013) and China is a large exporter of graduates, although these migration patterns may not continue.

The table provides some indication of where the new technology will be created.


Picture credit: Forbes magazine using WEF data on ‘recent STEM graduates’ in 2016.

Country STEM metric 1, 2016 STEM metric 2, 2030 Total population, 2015 Projected population, 2030 Per-capita metric 1, 2016 Per-capita metric 2, 2030
China 4,700 37,000 1,367,486 1,419,019 0.34% 2.61%
India 2,600 26,700 1,251,696 1,460,744 0.21% 1.83%
USA 568 4,200 321,369 359,403 0.18% 1.17%
Russia 561 4,500 142,424 138,215 0.39% 3.26%
Iran 335 81,825 93,459 0.41%
Indonesia 206 3,700 255,994 296,450 0.08% 1.25%
Saudi Arabia 3,000 33,826 8.87%
Mexico 2,200 140,063 1.57%
Brazil 2,000 228,720 0.87%
Japan 195 1,900 126,920 120,752 0.15% 1.57%
South Korea 1,600 49,003 3.27%
Turkey 1,500 86,671 1.73%
Germany 1,400 78,022 1.79%
UK 1,400 68,451 2.05%
Argentina 1,100 48,796 2.25%
France 800 69,604 1.15%
Canada 800 38,565 2.07%
Spain 700 52,446 1.33%


Picture credit: ‘finfacts’ blog from OECD data. (In comparison with the above, this chart does not include Iran because it is neither an OECD not G20 country.)

Vladimir Putin has said that the development of AI raises

“colossal opportunities and threats that are difficult to predict now”,


“the one who becomes the leader in this sphere will be the ruler of the world”

and that

“it would be strongly undesirable if someone wins a monopolist position.”


I have tried to get beyond the media hype and doom-mongering about the effect of robots and AI on jobs. To summarize the answers to the questions posed:

  • No, “47% of current jobs are under threat” does not mean that about half of jobs will disappear. It is that a very large number of jobs will be significantly affected by AI.
  • Yes, the new technology will have a big impact but technological revolutions also involve new ways of doing things, such as currently with the platform economy. It is these new processes that will surprise us. Some ‘vulnerable’ jobs will remain and some ‘safe’ jobs will disappear. The future is not the present with more robots.
  • Yes, robots will have a big impact but it is the technology of artificial intelligence that will have the biggest impact in the short term because it can be rolled out very quickly.
  • No, we cannot compete with the robots. But we can cooperate with them, with us doing the ‘lovely’ work in fewer hours and them doing the ‘lousy’ jobs. But this means we need to actively manage the economy to achieve this.
  • Yes, technological development does cause unemployment but this has manifested itself in the past as a reduction in general working hours.
  • Yes, this time is different from previous technological revolutions as it will be taking away cognitive rather than exclusively physical tasks. It is not just a problem of our imagination. There will not be an equal number of new jobs created as lost, because the AI will be able to do so many of those new jobs. “just because we can’t imagine what new jobs will come along doesn’t mean the next generation won’t” is much less true than it was before.
  • Yes, it is true that “self-driving vehicles will put millions of truck drivers out of work” but this is in the long In the meantime, driving will become more automated hence easier. Legislation should ensure that huge lumps of metal are not let loose onto roads unsupervised. After all, we still have train drivers.
  • Yes, there is a hollowing out of the jobs market. This is divisive and a serious threat to the cohesion of society.
  • Yes, technological unemployment is a problem but, if we manage to spread the work, it is a problem of disparity of income rather than the binary division between employed and unemployed. In any case, there is the problem of wealth redistribution.
  • Yes, Universal Basic Income may be a useful means of redistributing wealth but I believe a better solution is Universal Basic Services. The Freemium model may be a way of achieving UBS without increasing income tax or other taxes.
  • Yes, we should tax the robots but we should make sure this doesn’t have the consequence of stopping them doing the ‘dull, dirty and dangerous’ tasks that they could do.
  • Yes, we need to educate everyone for the future knowledge economy but: this is not about getting everyone to be AI experts. We need a world-class AI STEM education – but only for some (quality, not quantity) and the rest of us just need to be ‘AI-aware’ (aware of the ethical and other problems surrounding AI and Data Science). We need to educate for a world of less work: we must educate in order to spread the highly-paid work more equally across society and we need to educate in preparation for a more fulfilling world of less employed work and more opportunity for personal enterprise.

I have illustrated my arguments with some imagined futures but I doubt that they will actually come true in any way as described – these are only ‘un-forecasts’ after all. Accounts of the death of the university campus may be greatly exaggerated. There will be legal factors at play. Bots may not be allowed to impersonate real people – as suggested in help dementia patients in un-forecast 2. We may insist of having truck drivers sit in the huge chunks of metal hurtling around our roads, as we currently do on railway tracks. Automation may be thwarted by the ‘little things’. The San Francisco BART trains were designed in the 1970s to be self-driving but they are not,  defeated by the controlling the opening and closing of doors for the passengers, not the driving itself).


The current technological revolution is generally presented as a problem – that is, presented in negative terms: the threat of the robots taking our jobs, seemingly leaving us unable to provide for our own daily needs. We are passive in this. The technology is disruptive and cannot be stopped. We have no control over it.

But the problem is not one of technology. It never is, per se. Technology forces change but the matter of which direction the change will take us is a political question not a technical one. It is about who benefits from the technology; in whose interests does the technology serve?

The same can be said about the economy: who benefits from it and in whose interests does it serve? How should we reform the economy to overcome the current crisis in the West, and how should we manage the transition? Technology is just one factor that needs to be borne in mind when answering these questions.

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The Big Spiky Audacious Goal

Following the ‘Spiky Thoughts’ and ‘Spiky Logic’ blog posts, this is the third post on Spiking Neural Networks. It is part of a longer series which has a ‘Big Hairy Audacious Goal’: to create a relatively-simple, biologically-plausible hardware implementation example of a Spiking Neural Network hierarchy of predictors that is capable of intermittently learning from others and also capable of teaching others. That’s all!

Why? In order to just get to the Base Camp to climb up the notoriously-difficult learning curve to understand Hierarchical Predictive Coding (e.g. Karl Friston’s ‘Variational Free Energy’) in the brain! And by understanding, I mean really understanding. If you can replicate something in simulation then you really understand it. And no cheating: you have to be able to code up something without using other peoples’ libraries that do the heavy lifting (such as the many Python machine learning and neural network libraries).

What will be created will not be an implementation of a hierarchical predictive coding (HPC) network – it will be a hierarchy of reinforcement learning networks. But this will help understand how a neural net layer modifies its action in response to changes in its environment, which is something the HPC needs to be able to do and something that has been completely neglected in previous discussions of Variational Free Energy.


The Ten Step Way

Here then is a ‘Ten Step Way’ towards Hierarchical Predictive Coding Nirvana:

  • Step 1: Create an environment and an agent
  • Step 2: Biologically-plausible learning
  • Step 3: Combined unsupervised and supervised learning
  • Step 4: Reinforcement learning
  • Step 5: An Ensemble of predictors
  • Step 6: Society and Culture
  • Step 7: Adaptation
  • Step 8: Hierarchy of predictors
  • Step 9: Time delays
  • Step 10: Minimizing surprise through action and perception
  • Step 11: Beyond a simulation: Naïve hardware implementation
  • Step 12: Computationally-efficient: Event-driven learning

(Those last two steps are optional extras.)

In more detail…


Step 1: Create an environment and an agent

Create a simple environment in which an agent could interact with, could learn about the environment (find patterns in the world, i.e. unsupervised learning).

The environment needs to be sufficiently complex that optimum agent behaviour will vary dependent on some environmental parameters. There is then the prospect that we could make an agent that is intelligent enough to:

  • explore the world in order to devise a behaviour that is rewarding to the agent (i.e. adapt itself to the world. This would be through reinforcement learning.
  • notice a change in the environment and
  • modify behaviour to find a more optimum operating

(In the more complex environment of the real world, this is something where humans collectively have only really managed the second of these items!)

But the environment needs to be sufficiently simple that:

  • it is not computationally intensive (this is only an example, after all, which demonstrates principles and could then be expanded to a more complex environment.
  • We can verify that the environment and the agent have the potential to satisfy the above requirements. (It is much easier to get something working when you already know that it can possibly be done.)

So step 1 is about doing much the same for this new playground as was done in the ‘Spiky Logic’ blog post for an XOR gate:

  • Model the environment,
  • Create a spiking neural network of a particular topology and size sufficient.
  • Verify that that network has a topology and size sufficient for implementing near-optimal behaviour (a policy of generating actions from sense inputs) in that environment (verified through random walks through the environment).


Step 2: Biologically-plausible learning

From step 1, there is inference but no learning. I suppose the random walk of step 1 is an extremely simple form of learning, but it is learning carrier out but something outside of the environment-cum-agent (a god!). What is needed is a biologically-plausible means of learning which means that it is carried out solely by the agent within a ‘physical’ time and space: weight adjustment must be local to neurons, as we understand it to be done in real (biological) neurons, using information that is local to the synapse (i.e. of the pre-synaptic and/or post-synaptic neurons). Spike timing-dependent plasticity (STDP) is the general method to implement this Hebbian ‘neurons that fire together wire together’ behaviour.

Step 2 needs to implement unsupervised learning. That is:

  • by the agent on its own,
  • about the environment.


Step 3: Combined unsupervised and supervised learning

At present within typical artificial neural network practice, there is a sharp distinction in training neural nets between the three approaches:

  1. supervised learning,
  2. unsupervised learning, and
  3. reinforcement learning.

Considering just the first two, we humans have no such stark distinction. There is no sharp cut-off from ‘training’ to ‘inference’ at some teen age! That is not real intelligence, where we experience phases of supervised (in the presence of a teacher) and unsupervised learning, continuing to learn throughout adult life.

Supervised learning, in the form of learning in the presence of a teacher in the environment, is a particular form of unsupervised learning.

Step 3 is about ensuring that we have neuronal weight adjustment that is capable of both supervised and unsupervised learningSteps 2 avoids rushing in to develop a neuronal plasticity that is sufficient for supervised learning but not for supervised learning.



Step 4: Reinforcement learning

Step 4 then brings in online Reinforcement Learning – having the agent in its environment continuously learning.

The environment should to be biologically plausible but benign (the agent can continue to exist in the environment regardless of its behaviour, without being gobbled up by something) so that the agent can develop a policy (and in principle change that policy as it lives through a change in the environment).


Step 5: An Ensemble of predictors

At this and previous steps, the agent exists in its environment and is influenced by that environment. The agent can move around the environment but the location of the agent has no influence on the environment.

This allows us to have multiple agents existing in the same simple environment. If we  decouple action desired from action actually performed , an agent can have ‘involuntary’ movement. We can tie all the agents together as it were, and determine actual action by a weighted vote.

We need to have this decoupling in mind when we are developing the earlier steps. (Generally, this is the whole point of this BHAG planning.)



Step 6: Society and Culture

We should then be able to bring in agents or take out agents with little effect on overall behaviour, as though there is birth and death within the agent population.

And it should be possible to switch on teaching such that a newly-born agent is able to learn in the presence of an established agent. We should manually select the teacher to be the one that is the most effective (i.e. has the fewest involuntary actions).

There changes are biologically plausible and biologically inspired, apart from the last point. But this is just a stepping stone to the wider goal.

We should be able to demonstrate that behaviour of the group is improved through this teaching – that they are able to cope with additions to and removals from the population by passing knowledge down from one generation to the next.



Step 7: Adaptation

The agents need to be able to adapt their behaviour (policies) to cope with step changes in the environment.

It is possible for a single agent to achieve this? Maybe not.

The various agents of step 5 can have different parameters, such as learning weights, or ‘adventurousness’ (different propensities for exploring less optimal policies). Or we may have to introduce (give birth to) new agents with randomly better or worse policies than the consensus so that better policies steer the population’s behaviour towards something that is better suited to the new environment in which the agents find themselves.



Step 8: Hierarchy of predictors

And now a big milestone – achieving a hierarchy of agents in which:

  • Each agent has involuntary action, as before, but discrepancies are signalled by an error input rather than an actually input (there is an XOR in the input).
  • The agents are daisychained together (although at this stage, there is no extra delay experienced by agents higher up the hierarchy as a result of being connected to its environment via other agents).
  • At each stage in the hierarchy, there is weighted voting of actual action between an agent and that from the agent above.
  • Similarly, errors are daisychained upwards.



Step 9: Time delays

Up to now, there have been discrete timesteps in which agent and environment have worked in lockstep. At step 9, a time delay is introduced between agents.

Higher level predictors will have a larger latency (delay between sensing and action).

In Kahneman’s terms, lower levels ‘think fast’ and higher levels ‘think slow’. Compensating this though, it may be that different agents have different learning rates. Higher levels may learn quicker than lower ones but will also ‘forget’ old behaviour as the environment changes.


Step 10: Minimizing surprise through action and perception

At this point, we can see how far this Reinforcement Learning technological practice is away from Friston’s Variational Free Energy (and its ‘minimizing surprise through action and perception’) theory. How do Reinforcement Learning rewards lead to the long-term minimization of surprise and maintain exploration rather than just have exploitation in order to avoid the ‘Dark Room Problem’.


Step 11: Beyond a simulation: Naïve hardware implementation

We then have some optional-extra steps. Firstly, we shift from a computer program, programmed in Python, to a hardware description, programmed in Verilog or VHDL to implement in an FPGA. Every neuron is implemented in a different bit of hardware. Every synapse has a separate piece of wire connecting those neurons. This is to make completely separate point about simulation versus ‘the real thing’:


  1. We want to avoid being a bio-chauvinist and so accept that a piece of electronic hardware that does what a biological neuron does (from observations of how both behave), and
  2. We will only be convinced by implementations in which there is a one-to-one mapping between a part of the implementation and a part of the brain, i.e. not computer simulations,

Then, it because more difficult to argue against the (at face value, ridiculous) notions that that FPGA hardware wasn’t just a little bit conscious (according to Giuglio Tonini’s Integrated Information Theory)!

(This would including the option of shifting from the biologically-representative Izhikevich neuron models to engineeringly-practical ‘leaky-integrate-and-fire’ models.)


Step 12: Computationally-efficient: Event-driven learning

Another optional-extra step, incompatible to above, is to make a simulation more computationally efficient by transforming the cycle-based simulation of this small demo example to an event-driven implementation to see how much faster (in computer execution time) it is.



The Hard and the Difficult

All this will be with just simple applications. A following post will set out a simple ‘Spikeworld’ in which an agent can move, searching for food and compensating for the presence of a predator. The agent needs to be able to adjust its behaviour as food availability changes. It would therefore be an agent displaying intelligent behaviour, within a biology-like environment. I can then say ‘I’ve done the heavy lift here, you just need to scale this up to human intelligence now!

This goal is of course naively ambitious and I am sure I will have to miss out a step or two along the way (and thus compromise the project) and steer the project through alternative paths (and thus learn something in the process). And don’t hold your breath.

I would expect that Chris Eliasmith’s ‘How to Build a Brain’ book (which I haven’t seen) would provide a more biologically accurate view of the brain. The freely-available ‘How to build a brain: From function to implementation’ paper probably gives a flavour of it. But most of us don’t have the math for it. Instead, my approach is to write a relatively small amount of code to be able to run something that demonstrates brain-like qualities. You only really understand something if you can reproduce it – in simulation if not in reality. And hopefully that will convey some insight into how the brain works!


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Spiky Logic

My previous post (‘Spiky Thoughts’) set out some thoughts about how an efficient simulation of a spiking neural network might be achieved. It advocated:

  1. Event-driven as opposed to cycle-based simulation.
  2. Using simple ‘leaky integrate and fire’ (LIF) models of neurons, as opposed to models that reflected actual biological neuron behaviour more accurately.
  3. Being trained through ‘spike time-dependent plasticity’ (STDP), as opposed to the normal methods of ‘back-propagation’.

I hinted at training a spiking network to be an XOR gate – for demonstration purposes. Here, I provide some code to implement a spiking net to be an XOR gate, but I ignore all three previous motivations!:

  1. it is cycle-based,
  2. it uses the Izkikevich model of a neuron, and
  3. it doesn’t use STDP training – in fact, it doesn’t do training as such at all).

Why? Because it is a starting point:

  1. to demonstrate that a tiny network can behave as an XOR gate.
  2. to provide a reference point to see just how much more efficient an event-driven and/or LIF model implementation can be.
  3. to provide a ‘half-trained’ set of weights to help tweak STDP learning (it is easier to debug something you know is working but can be improved).

Spiky Logic

The C code below is based on the open-source code by Felipe Galindo Sanchez (see the research paper here). It has been re-written for my understanding and there is a slight modification. His inputs are single spikes on the A and B inputs of the XOR gate, with these spikes timed against a reference signal. The time that spike is injected into the network identifies whether it is a logic 0 (aligned with the reference spike) or logic 1 (5ms later). But I use the distance between 2 spikes to encode a logic 0 or logic 1, 6ms for the former, 12ms for the latter.

Both schemes demonstrate the time-dependent nature of spiking neurons, in contrast with second-generation rate neurons. The firing rates of my inputs and outputs is 2 firings per epoch in all cases. Note: an epoch is the interval in which 1 calculation (inference) is performed. It is 30ms here.

The code includes a mechanism to adjust the input away from the rigid 6ms/12ms specification:

  • skewing the spikes between the XOR gate’s inputs A and B, and
  • modifying the distnace between input spikes away from the precise 6ms/12ms values.

The network does not perform well in this regard but making this more robust (such as by using a larger network) is not of interest here.

The Network

The network comprises 10 nodes:

  • nodes 0…2: these are 3 input nodes, fully-connected to…
  • nodes 3…8: these are 6 neurons in a hidden layer, fully-connected to…
  • node 9: this is the 1 output neuron.

Nodes 0 and 1 are the A and B inputs for the XOR circuit. Node 2 is a training input but is not used because…

The Training

As already noted, there is no training as such. There are just 2 inputs (4 input states) and with limited variations or input spike timing (skewing and stretching). If there are 3 possible variations of skew (B input synchronized with the A input, 1ms earlier or 1ms later), there are only 3 x 4 = 12 input combinations.

So we simulate 12 runs in turn where each run lasts for 30ms (each run is called an ‘epoch’; simulation time is sliced into these epochs with inputs applied at the start and the output response judged at the end of the epoch).

There are only 24 weights in the network: 3 x 6 between the 3 inputs and the 6 hidden neurons and another 6 from those hidden neurons to the 1 output neuron.

A ‘random search’ algorithm is performed, which is just a fancy way of saying that we randomly generate sets of weights, simulate using them and monitor how good the result was (with an ‘error measurement’) and keep hold of the conditions that produced the most accurate output response. This provides all the infrastructure for training, without doing anything more complicated in which one set of tests uses weights that are derived from a previous run that has proved to be good.

Here is the basic code for the infrastructure for injecting inputs, simulating a network and judging the response of the network:

#include <stdio.h>
#include <stdlib.h>
#include <math.h>
// Randomization
#define get_random_logic()      ((rand()<(RAND_MAX/2)) ? 1 : 0) // 50% either 0 or 1

// Reporting: how much gets printed to stdout
#define QUIET   0
#define VERBOSE 1

// Function prototypes
void inject_input_spikes(
    int node,           // The input in question
    int logic_value,    // Inject a 0 or 1?
    int step,           // Current simulation times step
    int offset,         // By how much the input spikes will be injected later/earlier
    int stretch,        // By how much the input spikes will be stretched apart/closer
    int reporting);     // Whether it will report details to stdout
void reset_neuron_states(void); // All nodes (inputs and neurons) to their equilibrium state
void update_neuron(
    int step,           // Current simulation times step
    int layer,          // Neuron layer: distinguish input/hidden/output layer
    int neuron,         // The neuron in question
    int from_synapse,   // Synapse connections are from all neurons from this node...
    int to_synapse);    // ... to this node, inclusive.
int score_output(
    int wanted_output); // Should the output be a 0 or 1?
void dump_flags(
    int step);          // Current simulation times step

// Success counters
#define INVLD   0
#define BAD     1
#define GOOD    2

// Output error measurement
// e.g. anything within 2 of the ideal answer is 'good'
// Squaring: the error in this case will be 4.
#define NOT_BAD      4
#define WORST_SCORE 25

// Network configuration
// Nodes:
//  0..1    Inputs A and B into XOR gate
//  2       Training neuron, set to A xor B
//  3..8    Hidden neurons
//  9       Output neuron
//  The code expects synapse numbers to be contiguous:
//  * Hidden layer uses synapses from 0..2
//  * Output layer uses synapses from 2..8
#define INPUTS_LAYER            0
#define HIDDEN_LAYER            1
#define OUTPUT_LAYER            2

#define NUM_INPUTS              2
#define NUM_LAYER1_NEURONS      6
#define NUM_LAYER2_NEURONS      1
#define NUM_NODES               (NUM_INPUTS + NUM_TRAINING_INPUTS + NUM_LAYER1_NEURONS + NUM_LAYER2_NEURONS)  // Inputs and neurons
#define OUTPUT_NODE             (NUM_NODES - 1)

// Each simulation epoch is simulated for this many time steps...
#define NUM_STEPS                30

// Variation of input spike times; 3 means -1...+1
#define DEV   0             // Maximum deviation from ideal
#define VAR   (2*DEV+1)     // Variation

// Global variables

// Outputs: values for spike_train_state
#define SPIKE_TRAIN_INIT           0
#define SPIKE_TRAIN_INVALID       -1
#define SPIKE_TRAIN_LOGIC0         6
#define SPIKE_TRAIN_LOGIC1        12
int spike_train_state[NUM_INPUTS+NUM_LAYER1_NEURONS+NUM_LAYER2_NEURONS]; // For determining output value from spike times
int spike_flags[NUM_INPUTS+NUM_LAYER1_NEURONS+NUM_LAYER2_NEURONS]; // Flags for node spikes (inputs and neurons)

// Main simulation

float run_xor_snn(
    int num_epochs, // Number of simulations (with different inputs) to run
    int teaching,   // Is this a teaching run (with modification of weights) or just a test?
    int reporting)  // Will lots of status be reported to stdout?
    // XOR function: the function to be learnt by the network
    int input_a, input_b, output_y;

    int neuron;
    int epoch;
    int step;
    int error;
    int cum_error; // Cumulative score over all epochs
    float score;
    int count[4];
    int input_skew; // for skewing inputs A and B w.r.t. one another
    int input_stretch; // for stretching width of inputs (shorter or longer)

    // No previous spikes; set the times to 'ages ago'
    for(neuron=0; neuron <= OUTPUT_NODE; neuron++) {
        spike_train_state[neuron] = SPIKE_TRAIN_INIT;
    // A record of progress...
    cum_error = 0; count[GOOD] = 0; count[BAD] = 0; count[INVLD] = 0;

    // Main simulation loop
    for(epoch=0; epoch < num_epochs; epoch++){
        if (epoch < ALL_COMBINATIONS) { // Systematic stimulus             // Going through all the combinations             // of input logic and timing variations             switch(epoch % 4) {                 case 0 : input_a  = 0; input_b  = 0; break;                 case 1 : input_a  = 0; input_b  = 1; break;                 case 2 : input_a  = 1; input_b  = 0; break;                 case 3 : input_a  = 1; input_b  = 1; break;             }             input_skew    = (DEV==0) ? 0 : ((epoch >> 2)%VAR) - DEV; // -DEV...+DEV
            input_stretch = 0;
        } else { // Randomized stimulus
            input_a       = get_random_logic();
            input_b       = get_random_logic();
            input_skew    = (DEV==0) ? 0 : (rand() %VAR) - DEV; // -DEV...+DEV
            input_stretch = (DEV==0) ? 0 : (rand() %VAR) - DEV; // -DEV...+DEV;
        output_y = input_a ^ input_b; // XOR: This is the correct result
        if (reporting==VERBOSE) printf("EPOCH %d STIM %d XOR %d\n", epoch, input_a, input_b, output_y);
        for(neuron=0; neuron <= OUTPUT_NODE; neuron++)
            spike_train_state[neuron] = SPIKE_TRAIN_INIT;
        for(step=0; step < NUM_STEPS; step++){
            //printf("STEP %d \n", step);
            for(neuron=0; neuron <= OUTPUT_NODE; neuron++)
                spike_flags[neuron] = 0; // Ensure all flags are clear

            /*********** Generate inputs ***********/
            inject_input_spikes(0, input_a, step,          0, input_stretch, reporting);
            inject_input_spikes(1, input_b, step, input_skew,             0, reporting); // Delay by -2 to +2
            if(teaching) inject_input_spikes(2, output_y, step, 0,        0, reporting);

            /*********** Forward update of network ***********/
            // [Fixed size!!!]
            for(neuron=0; neuron <= 2; neuron++) // Inputs
                update_neuron(step, 0, neuron, 0, 0);
            for(neuron=3; neuron <= 8; neuron++) // Hidden layer
                update_neuron(step, 1, neuron, 0, 2);
            for(neuron=9; neuron <= 9; neuron++) // Output layer
                update_neuron(step, 2, neuron, 2, 8);
            if (step == 0) {
            if (reporting==VERBOSE) dump_flags(step);
        /*********** Determine how good the outputs were ***********/
        error = score_output(output_y); // a high score is bad
        cum_error += error;
        if (error <= NOT_BAD) {
            count[GOOD] += 1;
            if (reporting==VERBOSE) printf("BADNESS good    wanted %d trainstate %d error %d cumulative %d\n", output_y, spike_train_state[OUTPUT_NODE], error, cum_error);
            //if (reporting==VERBOSE) printf("RESULT good    %d XOR %d shouldbe %d (now %d %d %d)\n", input_a, input_b, output_y, count[GOOD], count[BAD], count[INVLD]);
        } else if (error == WORST_SCORE) {
            count[INVLD] += 1;
            if (reporting==VERBOSE) printf("BADNESS invalid wanted %d trainstate %d error %d cumulative %d\n", output_y, spike_train_state[OUTPUT_NODE], error, cum_error);
            //if (reporting==VERBOSE) printf("RESULT invalid %d XOR %d shouldbe %d (now %d %d %d)\n", input_a, input_b, output_y, count[GOOD], count[BAD], count[INVLD]);
        } else {
            count[BAD] += 1;
            if (reporting==VERBOSE) printf("BADNESS bad     wanted %d trainstate %d error %d cumulative %d\n", output_y, spike_train_state[OUTPUT_NODE], error, cum_error);
            //if (reporting==VERBOSE) printf("RESULT bad     %d XOR %d shouldbe %d (now %d %d %d)\n", input_a, input_b, output_y, count[GOOD], count[BAD], count[INVLD]);
    // Worst possible error is WORST_SCORE*num_epochs
    // Make the score within a range of 0.0 (worst) to 1.0 (perfect)
    score = 1.0 - (float)cum_error / (float)(WORST_SCORE*num_epochs);
    if (reporting==VERBOSE) printf("GOODBADINV good %d bad %d invalid %d score=%.3f\n", count[GOOD], count[BAD], count[INVLD], score);
    return score; // Overall score of how big the errors were over all the simulation epochs
} // run_xor_snn

// To display the maps of spiking of all the neurons over the timesteps
void dump_flags(int step) {
    int neuron;
    printf("STEP %4d SPIKES ", step);
    for(neuron=0; neuron <= OUTPUT_NODE; neuron++)          if (spike_flags[neuron])             printf("1");         else             printf(".");     printf("\n"); } 

The scoring system for selecting the best set of weights is as follows:

  • If a logic 0 is the correct output and the network generates 2 spikes, 6ms apart, that is a perfect output and the error value is 0.
  • If they are 7ms or 9ms apart, the distance away from ideal is 1 and the error value is the square of this (1!).
  • Likewise, spikes 6ms or 10ms apart produce an error of 4, and so on up to a maximum error score of 25 for wider deviations (which is deemed to be ‘bad’).
  • The same scheme applies to logic 1 with the ideal separation on 12ms.
  • If there are not exactly 2 spikes, the output is deemed to be ‘invalid’ and given a maximum error score of 25.

When it is run it will report spike maps like this (1 xor 1 produces a correct 0) which show which neurons fire when (input node 0 is left-most, output neuron 9 is right-most; a 1 indicates the node is firing)…

STEP    0 SPIKES ..........
STEP    1 SPIKES ..........
STEP    2 SPIKES ..........
INSPIKE neuron 0 start  step 3
INSPIKE neuron 1 start  step 3
STEP    3 SPIKES 11........
STEP    4 SPIKES ..........
STEP    5 SPIKES ...11...1.
STEP    6 SPIKES ..........
STEP    7 SPIKES ..........
STEP    8 SPIKES ...1....1.
STEP    9 SPIKES ....1.....
STEP   10 SPIKES .........1
STEP   11 SPIKES ..........
STEP   12 SPIKES ...1......
STEP   13 SPIKES ........1.
STEP   14 SPIKES ..........
INSPIKE neuron 0 logic1 step 15
INSPIKE neuron 1 logic1 step 15
STEP   15 SPIKES 11..1.....
STEP   16 SPIKES ...1.....1
STEP   17 SPIKES ........1.
STEP   18 SPIKES ....1.....
STEP   19 SPIKES ...1......
STEP   20 SPIKES ..........
STEP   21 SPIKES ........1.
STEP   22 SPIKES ...11.....
STEP   23 SPIKES ..........
STEP   24 SPIKES ..........
STEP   25 SPIKES ..........
STEP   26 SPIKES ...1......
STEP   27 SPIKES ..........
STEP   28 SPIKES ..........
STEP   29 SPIKES ..........
OUTPUT good    wanted 0 trainstate 106 error 0 cumulative 1
GOODBADINV good 4 bad 0 invalid 0 score=0.990

This shows the last of 4 runs (epochs) which produced a perfect output (error=0). All 4 runs produced good outputs but one of them, had the timing off by 1ms.


The Neuron

Eugene Izhikevich’s model of the neuron (IEEE Transactions on Neural Networks, vol. 14 no. 6, November 2003) will be used instead of the leaky integrate-and-fire model. The model is expressed as differential equations with 2 variables (u and v) and 4 parameters (a, b, c and d) and shown in the figure below. The variable v represents the membrane potential – the ‘output voltage’ which spikes. Note, in case you are unfamiliar with the notation: v’ represents the gradient dv/dt and u’ represents du/dt. But you don’t need to worry about the math – just see the ‘Izhikevich equations’ part of the code below.


Figure credit: IEEE

In Galindo Sanchez’s C code, the parameters

  • a=0.02, b=0.2, c=-65mV, d=8

are used for excitatory neurons and

  • a=0.10, b=0.2, c=-65mV, d=2

are used for inhibitory neurons.

Thus, according to Izhkevich’s classification, we are using Regular Spiking(RS) excitatory and Fast Spiking (FS) inhibitory neurons.

 // Model time step #define HALF_MILLISECOND    0.5 #define MILLISECOND         1.0 //Decay of synapses: #define TAU_S               10.0    // Time constant (ms) #define S_DECAY_FACTOR      (1.0 -(MILLISECOND / TAU_S)) #define EXCITATORY_SYNAPSE_POTENTIAL      0.0 // mV Excitatory synapse potential #define INHIBITORY_SYNAPSE_POTENTIAL    -85.0 // mV Inhibitory synapse potential // Inhibitory / excitatory neurons #define NUM_INHIBITORY 2 int neuron_is_inhibitory(int neuron) {     // Only the first NUM_INHIBITORY neurons in the hidden layer are inhibitory     if ((neuron >= FIRST_HIDDEN_NODE)&&(neuron < FIRST_HIDDEN_NODE+NUM_INHIBITORY)) return 1;     else return 0; } // function prototype, for spikes generated either at inputs or by neurons: void generate_spike(int neuron, int step); // Store for all nodes; many values in these arrays will not be used // Only use from NUM_INPUTS onwards float syn_s[NUM_NODES];  float syn_weights[NUM_NODES][MAX_NUM_SYNAPSES]; float izh_u[NUM_NODES]; // Izhikevich model 'u' state float izh_v[NUM_NODES]; // Izhikevich model 'v' state void update_neuron(int step, int layer, int neuron, int from_synapse, int to_synapse) {     /************* Update synaptic inputs *****************/     int synapse;     syn_s[neuron] *= S_DECAY_FACTOR;     if (izh_v[neuron] >= 35.0) { // firing input (t-1)
        syn_s[neuron] += 1.0; // A neuron spiking will create a decaying post-synaptic potential
    } else if ((layer==INPUTS_LAYER) && (spike_flags[neuron] == 1)) { // synaptic input
        syn_s[neuron] += 1.0; // Likewise, create a decaying post-synaptic potential
    /************* Update synaptic conductances *****************/
    // sum of weights
    float sum_g_excit = 0.0;
    float sum_g_inhib = 0.0;
    // Perform sum of synaptic conductances per neuron
    if (layer > INPUTS_LAYER) {
        for (synapse = from_synapse; synapse <= to_synapse; synapse++) {             if (neuron_is_inhibitory(synapse))                 sum_g_inhib += syn_weights[neuron][synapse] * syn_s[synapse];             else                 sum_g_excit += syn_weights[neuron][synapse] * syn_s[synapse];         }     }     /************* Izhikevich equations *****************/     float dv, du; // deltas: dv/dt and du/dt     float izh_I;     int iteration;     if (layer==INPUTS_LAYER) {         // Not used (setting to equilibrium point just for information only)         izh_v[neuron]  = -70.0;          izh_u[neuron]  = -14.0;     } else if (izh_v[neuron] >= 35.0) { // Firing; parameter c=-65mV
        izh_v[neuron]  = -65.0; // Reset (refractory period); parameter c=-65mV
        izh_u[neuron] += neuron_is_inhibitory(neuron) ? 2.0 : 8.0; // ms; parameter d
        generate_spike(neuron, step);
    } else { // not firing
        izh_I = (sum_g_excit * (EXCITATORY_SYNAPSE_POTENTIAL - izh_v[neuron]))
              + (sum_g_inhib * (INHIBITORY_SYNAPSE_POTENTIAL - izh_v[neuron]));

        for(iteration=1; iteration<=2; iteration++) { // Two 0.5 ms steps             // v' = 0.04v^2 + 5v + 140 - u + I    (1)             dv = (((0.04 * izh_v[neuron]) + 5.0) * izh_v[neuron]) + 140.0 - izh_u[neuron] + izh_I;             // u' = a(bv - u)  (2)             if(neuron_is_inhibitory(neuron)) {                  du = 0.1  * ((0.2 * izh_v[neuron]) - izh_u[neuron]); // parameters a and b             } else {                  du = 0.02 * ((0.2 * izh_v[neuron]) - izh_u[neuron]); // parameters a=0.02; b=0.2             }             izh_v[neuron] += (dv * (HALF_MILLISECOND));             izh_u[neuron] += (du * (HALF_MILLISECOND));         }         if(izh_v[neuron] > 35.0) { // Saturate
            izh_v[neuron] = 35.0;

// Force all neurons to their equilibrium state
void reset_neuron_states(void) {
    int neuron;
    for(neuron=0; neuron <= OUTPUT_NODE; neuron++) {
        izh_u[neuron] = -14.0; izh_v[neuron] = -70.0; syn_s[neuron] = 0.0;

The spike_flags[n] indicates whether node n has fired and is used for printing out spike train maps for visualization and, here, for handling input spikes (as opposed to spikes from other neurons).

It is the synaptic current (izh_I) that feeds into the Izhikevich-model. This is the (exponentially decaying) sum of the currents originating from synaptic firing from all the neuron’s synapses. If we are bothered about units, we are generating a current (I) from voltages. The ‘g’ in the sum_g_excit and sum_g_inhib variables is the standard notation for conductance which is the reciprocal of electrical resistance (there is the well-known equation V=IR and its lesser-known opposite equation  I=gV). But basically, we are just calculating a weighted sum of the inputs to produce a ‘postsynaptic potential’ (‘potential’ = voltage) that controls the (Izhikevich-modelled) firing of the neuron (it fires when excitatory firings push the membrane voltage v up above 30mV).

The weights are stored in the 10 x 10 array syn_weights, but it is only the 3 x 6 input-to-hidden-layer connection values and 6 x 1 hidden-to-output-layer connection values that are used.

Inputs and Outputs

Inputting spikes into the network is a straightforward setting of flags but,
in generating spikes, we maintain a ‘spike_train_state’ so that we can score the output of the network in order to optimize weight settings.

// Inputs
#define START_TIME                3  // Just after resetting everything (but allow for -2 input_skew)
#define INPUT0_TIME               9  // Separation of 6
#define INPUT1_TIME              15  // Separation of 12

void generate_spike(int neuron, int step) {
    // Put information into the various data structures
    spike_flags[neuron] = 1;
    // Sequence of spike_train_state values:
    // 0. Initially 100 (no spikes can be generated at this time)
    // 1. Then set to time of 1st spike (range 1...99)
    // 2. Then set to the delta between 1st and 2nd spikes plus 100.
    // 3. If more than 2 spikes, set invalid
    if      (spike_train_state[neuron] == SPIKE_TRAIN_INIT ) // First spike
            {spike_train_state[neuron] = step; } // Time of 1st spike
    else if (spike_train_state[neuron] <= NUM_STEPS ) // Second spike
            { spike_train_state[neuron] = SPIKE_TRAIN_DELTA_OFFSET + step - spike_train_state[neuron]; } // Delta
    else    { spike_train_state[neuron] = SPIKE_TRAIN_INVALID; }

void inject_input_spikes(int node, int logic_value, int step, int offset, int stretch, int reporting) {
    if (step==START_TIME + offset) {
        generate_spike(node, step);
        if(reporting==VERBOSE){printf("INSPIKE node %d start  step %d\n", node, step);}
    if ((step==(INPUT0_TIME + offset + stretch))&&(logic_value == 0)) {
        generate_spike(node, step);
        if(reporting==VERBOSE){printf("INSPIKE node %d logic0 step %d\n", node, step);}
    if ((step==(INPUT1_TIME + offset + stretch))&&(logic_value == 1)) {
        generate_spike(node, step);
        if(reporting==VERBOSE){printf("INSPIKE node %d logic1 step %d\n", node, step);}

int score_output(int wanted_output) {
    // To judge success
    int diff;
    int result;
    if (spike_train_state[OUTPUT_NODE] < SPIKE_TRAIN_DELTA_OFFSET) { // Not exactly 2 spikes         result = WORST_SCORE;      } else if   (wanted_output == 1) { // error = difference squared         diff = (spike_train_state[OUTPUT_NODE] - SPIKE_TRAIN_DELTA_OFFSET - SPIKE_TRAIN_LOGIC1);         result = diff * diff;     } else { // (wanted_output = 0) // error = difference squared          diff = (spike_train_state[OUTPUT_NODE] - SPIKE_TRAIN_DELTA_OFFSET - SPIKE_TRAIN_LOGIC0);          result = diff * diff;     }     if (result > WORST_SCORE) { result = WORST_SCORE; }
    //printf("OUTPUT wanted %d trainstate %d error %d\n", wanted_output, spike_train_state[OUTPUT_NODE], result);
    return result;

The Main Program

The run_xor_snn function, above, simulates the network with all the input combinations and provides a score on how well the network has performed. The main program calls this function over and over again (for NUM_TRIALS trials) with different (randomized) set of weights each time, keeping note of the best set of weights it has found and then re-run that best set at the end with verbose reporting. (For a large number of trials, the output will be gigabytes if the verbosity is not set to QUIET before this at the end.)

There is some coding in place in preparation for training but that will need to be developed a little bit further.

#define NUM_TRIALS  10000000
#define TEST         0
#define LEARN         1
#define TEACH         1

// Function prototypes
void fix_training_weights(float weight); // Set all the weights from TRAINING_INPUT_NODE to this 1 value
void clear_weights(void);
void randomize_weights(float scaling, int from_neur, int to_neur, int from_syn, int to_syn);
// e.g. randomize_weights(1.0, 3, 8, 0, 2) operates on all weights connecting input nodes 0..2 to neurons 3...8.
// Simlarly for reporting...
void dump_weights(float weights[NUM_NODES][MAX_NUM_SYNAPSES], int from_neur, int to_neur, int from_syn, int to_syn);
void copy_weights(float from[NUM_NODES][MAX_NUM_SYNAPSES], float to[NUM_NODES][MAX_NUM_SYNAPSES]);

void main(void) {
    int trial, verbosity, learning;
    float best_syn_weights[NUM_NODES][MAX_NUM_SYNAPSES];

    verbosity = QUIET; //verbosity = either QUIET or VERBOSE
    learning  = TEST; //learning = TEACH or TEST;
    srand(1); // seed
    float this_score, best_score;
    int best_trial = -1;
    best_score = 0.0; // Worst is the output of every trial being invalid
    for(trial=0; (trial<NUM_TRIALS) && (best_score < 1.0); trial++) {         if ((trial%1000)==0) printf("TRIALNOW %d bestscore %f besttrial %d\n", trial, best_score, best_trial);         if (verbosity==VERBOSE) printf("TRIAL %d\n", trial);         clear_weights();         randomize_weights(1.0, 3, 8, 0, 2); // Hidden layer         randomize_weights(1.0, 9, 9, 2, 8); // Output layer         if(learning) {             fix_training_weights(1.0);             this_score = run_xor_snn(100, learning, verbosity);         } else {             fix_training_weights(0.0);             this_score = run_xor_snn(ALL_COMBINATIONS, learning, verbosity || (trial == 18));         }         if (verbosity==VERBOSE) dump_weights(syn_weights, 3, 8, 0, 2); // Hidden layer &syn_weights,          if (verbosity==VERBOSE) dump_weights(syn_weights, 9, 9, 2, 8); // Output layer &syn_weights,          if (this_score >= best_score) {
            best_score = this_score;
            best_trial = trial;
            printf("BESTSOFAR %f trial %d\n", best_score, best_trial);
            dump_weights(syn_weights, 3, 8, 0, 2); // Hidden layer &syn_weights,
            dump_weights(syn_weights, 9, 9, 2, 8); // Output layer &syn_weights,
            copy_weights(syn_weights, best_syn_weights); // Store for reference later
            this_score = run_xor_snn(ALL_COMBINATIONS, TEST, VERBOSE); // test for all 4 input combinations and all VAR skews
    printf("VERIFYBESTSCORE %f trial %d\n", best_score, best_trial);
    copy_weights(best_syn_weights, syn_weights);
    dump_weights(syn_weights, 3, 8, 0, 2); // Hidden layer &syn_weights,
    dump_weights(syn_weights, 9, 9, 2, 8); // Output layer &syn_weights,
    this_score = run_xor_snn(ALL_COMBINATIONS, TEST, VERBOSE); // test for all 4 input combinations and all 5 skews

And finally

And finally, below are the innards of the functions used above that have not yet been defined. They all handle weights.

void clear_weights(void) {
    int neuron, synapse;
    for(neuron=0; neuron < NUM_NODES; neuron++) {
        for(synapse=0; synapse < MAX_NUM_SYNAPSES; synapse++) {
            syn_weights[neuron][synapse] = 0.0;

#define get_random_weight()     (2.0*rand()/RAND_MAX-1.0) // Float between -1.0 and +1.0
void randomize_weights(float scaling, int from_neur, int to_neur, int from_syn, int to_syn) {
    // Adds a scaled random amount to all weights.
    // Use to set weights initially after a clear
    // or to locally-disturb good weights during simulated annealing
    int neuron, synapse;
    for(neuron=from_neur; neuron <= to_neur; neuron++) {
        for(synapse=from_syn; synapse <= to_syn; synapse++) {
            syn_weights[neuron][synapse] += scaling * get_random_weight();

void fix_training_weights(float weight) {
    // STDP may update these but we want to fix them to control training
    int neuron;
    for(neuron=0; neuron < NUM_NODES; neuron++) {
        syn_weights[neuron][TRAINING_INPUT_NODE] = weight;

// For saving and restoring good sets of weights and potentially more...
void copy_weights(float from[NUM_NODES][MAX_NUM_SYNAPSES], float to[NUM_NODES][MAX_NUM_SYNAPSES]) {
    int neuron, synapse;
    for(neuron=0; neuron < NUM_NODES; neuron++) {
        for(synapse=0; synapse < MAX_NUM_SYNAPSES; synapse++) {
            to[neuron][synapse] = from[neuron][synapse];

void dump_weights(float weights[NUM_NODES][MAX_NUM_SYNAPSES], int from_neur, int to_neur, int from_syn, int to_syn) {
    int neuron, synapse;
    // STDP may update these but we want to fix them to control training
    for(neuron=from_neur; neuron <= to_neur; neuron++) {
        for(synapse=from_syn; synapse <= to_syn; synapse++) {
            printf("WEIGHT w[%d][%d] = %6.3f ;\n", neuron, synapse, weights[neuron][synapse]);

Next time: We are now ready to add supervised learning to the code, to use STDP to train networks rather than performing a blind random search.

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Spiky Thoughts

Now here’s a techy post that might appeal to your Dr Frankenstein side. These are the early fumblings towards building a brain, albeit one of very small intelligence (and without any means of walking out of the lab). It is for personal interest but might lead towards something that would be a good, alternative teaching introduction to computational neuroscience and/or neuromorphic engineering. This is because it starts with ‘third generation’ (‘neuromorphic’, spiking) neural networks rather than the classical, currently dominant ‘second generation’ of bio-inspired networks (deep learning, convolutional neural networks). The aim is to have neurons that behave much more like the (spiking) way that real neurons behave and learning more like they learn (using ‘spike timing dependent plasticity’ rather than ‘back-propagation’).

I want to ditch the mathematics (of ‘back-propagation’, ‘stochastic gradient descent’ and machine learning optimizations) and the highly-abstracted programming environments to get down to something as simple as possible that closely resembles the behaviour of the biology, where we can get some intuition of the underlying complexity of spiking neural networks.

These are the rambling thoughts of a novice – so there are sure to be errors within. ‘A little knowledge is a dangerous thing.’ But hopefully it is useful for some to get a low-level understanding.

This is different from the normal introductory approach of grabbing some pre-prepared data, training a network that is described in just a few lines of Python, and running it to do something impressive. Here, what the resulting design for a spiking neural net might be able to do is not relevant. Maybe just being able to train it to be an XOR gate is enough for me for starters.

Spiking Neural Networks

A ‘second generation’ artificial neural network consists of many nodes (neurons) connected by synapses. Each synapse has a ‘weight’ number indicating the strength of connection between the two nodes. Each neuron has an output value at any instant. A neuron is updated by producing a sum of the products of the synapse weights and the neuron output values of all the driving neurons and assing this sum through a non-linear function such as a sigmoid function.

The output values of the artificial neurons are analogous to the firing rates of the outputs of real neurons – how many times a neuron outputs a spike, per second. The artificial neurons are rate neurons.

In a biological neuron, a firing of a neuron A may lead to signalling crossing a synapse to neuron B where it will increase the membrane voltage within the neuron (actually, it will make it less negative rather than more positive and this is assuming it is an excitatory rather than inhibitory neuron). Over time, the membrane voltage will return to equilibrium. But if there are enough firings from the various synapses of that neuron in a short enough period of time, it will push the voltage over a threshold which will cause the neuron to fire: an ‘action potential’ will propagate down the neuron’s axon to synapses that connect to other neurons.


Leaky integration of spike trains (Credit: Science Direct)

The artificial neurons in a ‘third generation’ (spiking) neural network (SNN) is much more like the biological neuron than rate neurons are. They model a membrane voltage that varies in time and responds to input (post-synaptic) spikes, and will generate output firings (spikes) when the membrane exceeds a threshold. Their outputs are therefore ‘spike trains’ (timed sequences of spikes) just like with real neurons.

The Leaky Integrate-and-Fire Neuron

Leaky integrate and fire (LIF) neuron model is one of the simplest neuron models. Its behaviour is as follows:

  • It models the neuron membrane voltage which sits at equilibrium at -75mV.
  • At other voltages, it will exponentially decay towards this voltage, whether from lower or higher voltages.
  • A spike from a pre-synaptic neuron will instantaneously increase the voltage in proportion to the strength (weight) of the synapse, if excitatory, or decrease the voltage in proportion to the strength of the synapse if inhibitory.
  • If the voltage ever exceeds -50mV, the neuron will fire, triggering a spike at its output. Its voltage is reset to -100mV at this point.

This last item is a bit different here from the normal LIF neuron: the refractory period (in which crossings of the threshold shortly afterwards will not trigger further action potential spikes) is not explicitly modelled with a time parameter. Instead, the voltage will recover to equilibrium over time determined by the exponential time constant. Immediately after a spike, no further synaptic spike will be able to trigger a neuron spike because all weights will be substantially less than 50mV equivalent excitatory. This results in an absolute refractory period. When equilibrium is nearly restored, synaptic spikes (or more likely, simultaneously-occurring spikes) will be able to trigger a neuron spike. There is therefore a relative refractory period.


Leaky Integrate and Fire neuron with refractory response (Credit: Science Direct)

This model is algorithmic rather than determined by differential equations, which is more normal for neuron models.

Implementation = Simulation

An implementation of a spiking neural network is the same thing as creating a simulator  and running that. There are 3 basic forms of science/engineering simulation:

  1. Cycle-based: time is broken down into regular discrete time steps and every section of the simulation space is re-calculated for this timestep.
  2. Event-driven simulation: Only update a sub-section of the simulation when an input to that sub-section changes.
  3. Continuous simulation: typically using differential equations.

Where things don’t change much from one timestep to the next, cycle-based simulation will be inefficient. Rate-based (‘second generation’) neural networks are typically presented with very different data from cycle to cycle (e.g. a different picture) and so are cycle-based.

Simulating spiking neurons this way would be very inefficient. It takes many timesteps to present a value (encoded within the spike train) to the network. It would be vastly slower than an equivalent rate-based network.

Neuron dynamics are generally described with differential equations (for example, the Izhikevich model) and this would lend itself to continuous simulation – but this approach is much slower still and is to be used for accuracy – in neuroscience rather than neuromorphic engineering.

Action potentials are spike events. An implementation of a spiking network should be event-driven – we only perform neuron updates when there are spikes on its synapses. It is hoped that this will make spike-based networks more efficient (in terms of computation and hence also energy) than rate-based neurons.

Spike Time-Dependent Plasticity

According to the well-known Hebbian saying:

‘Cells that fire together wire together’

The learning (adjustment of weights) in spiking neural networks is much closer to this than rate-neuron learning is.

If a synaptic spike causes the neuron to spike (the synaptic spike precedes the neuronal spike), a weight will be strengthened. The shorter the time difference, the larger the effect. This is shown in the figure below. This will be modelled as an exponential relationship.

Conversely, if a synaptic spike follows closely behind a neuronal spike), the weight will be weakened.  – also with an The shorter the time difference, the larger the effect. This is shown in the figure below. This will be modelled as an exponential relationship.

Credit: Jneurosci

Simulating a Timestep.

An array of flags is maintained – one per neuron plus one per input – to indicate whether a spike event has occurred for the current timestep. At the start of a timestep, spike event flags will have been set up by whatever is driving the simulation.

For each timestep, the following tasks will be performed:

  1. Spike Propagation and Synapse Depression: For each of the inputs to the network in which the respective event flag is set, find out which nodes (neurons) the current node is connected to via synapses and update these in turn. The updating of these neurons may cause then to spike (and their event flags to be set) which will recursively trigger further neurons to be updated, ultimately through to the outputs. Propagating spikes through the network may also result in some synapses being weakened.
  2. Synapse Potentiation: For each of the neurons in which the respective spike event flag is set, find out which neurons are at its synaptic inputs and possibly strengthen those synapses. Clearing the event flag for a spiking neuron will result in all the neurons having cleared flags ready for the next timestep.
  3. Move to the next timestep: wait whilst whatever is driving the simulation to set the flags of the spiking inputs appropriately. When given the OK, increment the timestep counter and repeat the tasks.

Updating a Neuron

  1. If the neuron’s spike time is the same as the current time, the neuron has already spiked as a result of an alternative update path through the network so there is no need to do anything more. (Checking the neuron’s event flag will also have been set.)
  2. If the neuron’s update time is the same as the current time, the neuron has already been visited on this timestep but there was no resulting spike. Otherwise, the neuron’s membrane voltage needs to be updated, based on the time now and its last-recorded update time and voltage (see elsewhere: ‘Event-Driven Exponentials’). The neuron’s update time will be set to the current time as part of this update.
  3. If the synapse is inhibitory, the voltage needs to be reduced by the synapse weight value (there may be a global scalar factor applied to the weight before this adjustment). The voltage cannot go below -100mV.
  4. If the synapse is excitatory, the voltage needs to be increased by the synapse weight value (again, there may be a global scalar factor applied to the weight before this adjustment).
  5. If the voltage exceeds the threshold (-50mV), a spike will be triggered (see the ‘Neuron Spiking’ below). Otherwise, the following needs to be performed…
  6. If a synaptic spike occurs recently after a neuron has spike, then the synapse strength needs to be reduced (see ‘Spike Time-Dependent Plasticity’). The check for this is if the neuron’s spike time is less than 50ms (the window duration) prior to the current timestep.

For the recursive updating, a stack will need to be maintained. The neuron’s ID and the output connection number will need to be put onto this stack to achieve this.

Neuron Spiking

When a neuron spikes:

  1. The neuron’s event flag is set.
  2. The membrane voltage is set to -100mV, putting the neuron into the refractory state.
  3. All the neurons that are driven by this neuron then need to be updated (the ‘Update Neuron’ sequence above, recursively) in turn.

Synapse Potentiation

The synapse that caused a neuron to fire will need to have its strength increased. But there will be other synapses that will need to be strengthened too, if they have occurred within the last 50ms (the window duration).

Synapses firing after a neuron fires (‘Long Term Depression’) can be handled as part of the normal spike propagation through the network. But for ‘Long Term Potentiation’ (strengthening weights), at the time a synapse fires, we don’t know whether the neuron will be triggered soon – simulation time hasn’t got that far yet.

Instead, we have to look back at all the inputs of a neuron that has just spiked and see if any of the driving neurons spiked within the last 50ms. If they do, the synapses need to be strengthened to an extent determined by the how long ago the driving neuron spiked.

This is done in a separate phase, after spike propagation. It is done this way because it is possible for more than one neuron’s synapse to spike at same timestep that the neuron spikes. By recording which neurons have spiked and doing the updates after spike propagation, we ensure the updates are not done twice.


The basic mechanism for second-generation (rate-neuron) neural nets to learn (or rather, to be taught through training) is through back-propagation: propagating an error (mismatch between what the network produced at the output and what is desired) back through the network, adjusting weights proportionately. Over time, it is hoped that this error adjustment leads to more optimum weight configurations, through a process called ‘stochastic gradient descent’. This is all very intensive computationally. It is also best to learn in batches and this is a significant overhead on memory.

Hence, second-generation neural nets are predominantly used just for inference within their application environment, after having been trained (given ‘supervised learning’) in a more computationally-rich environment. They do not learn ‘out in the field’.

In contrast, spiking neural nets learn by STDP (spike timing-dependent plasticity): when a synapse firing causes the neuron’s potential to exceed the critical threshold and hence to fire, its weight is adjusted – exponentially according to how close the timing difference was. This is very much in accordance with the Hebbian learning concept that ‘neurons that fire together, wire together’. The neurons adjust their weights locally. This is not so computationally intensive and doesn’t need to be batched.

Hence, third-generation neural nets are predisposed towards ‘unsupervised learning’, amenable to learning ‘out in the field’ (although, is this good learning?).

Doing supervised learning with SNNs is not so straightforward. (One method is to train a second-generation network that has the same topology and then transfer the weights to the SNN!) In “A new biologically plausible supervised learning method for spiking neurons”, Taherkhani et al present a method of supervised learning for SNNs as follows:

  • Neurons throughout the network have extra inputs (training inputs).
  • During supervised training, the desired outputs are set on these training inputs.
  • The weights between these training inputs and the neurons being trained are very strong (compared with the initially-random normal synaptic connection weights) and are not modified through STDP.
  • Gradually over time, the neurons will learn to behave such that the network’s outputs follow the training inputs. (When the firing of training neurons triggers neuronal spikes, normal inputs to the neurons that fired around the same time will have their weights adjusted.)
  • After training, inference can proceed with the training inputs left inactive.

Presumably, the strength of the training inputs could be reduced gradually so that the network would gradually shift over from ‘supervised’ to ‘unsupervised’ operation. This is in contrast to the stark training/inference dichotomy with second-generation networks.

(Second-generation networks: output that compute something like y = sigmoid(x . w + b) where x . w is the scalar product on the input vector with the weights vector, which produces a sum of products. And b is the bias. For the SNNs, it is like putting the training information onto the biases of neurons. Neuro-biologically, perhaps this model adjustment is similar to it is the effect of neuro-modulators (such as serotonin / dopamine) which have a widespread influence on brain behaviour, connected with emotions?)

One enhancement of theirs, (with some biological justification) is for STDP to increase small weights much more than stronger weights.

In what follows, I will assume that any supervised learning of SNNs employs this method.

Number Representation

The 3 main quantities that need to be stored for spiking neurons are:

  • Membrane voltages: range from -100mV to 65mV in biology
  • Synapse weights: unsigned
  • Spike times: unsigned integers

It should be possible to use 16-bit integer values (‘int16’) for both weight values and membrane voltages. Floating point types are generally used for neural networks because the compute platforms have the necessary hardware already. Memory is the issue here and the IEEE 754-2008 standard defines a 16-bit Half-precision floating-point format ‘float16’ which is obviously no worse than ‘int16’ for storage. Spike neurons will be event-driven and have no need to calculate large sum-of-products. We can ensure there is no overflow of quantities. And float16 only has a 10-bit mantissa so unsigned int16 (16-bit mantissa) is preferable for better precision.

Membrane voltages

For membrane voltages, any unsigned integer range can represent this, e.g. 0= ‘-100mV’and 65535= ‘-65mV’. The spike threshold (-50mV) and resting potential (-70mV) constants can be set accordingly. But voltage values above the threshold are not relevant so if we use 0= ‘-100mV’and 32767= ‘-50mV’ (half full scale is 50mV) then the sensitivity increases from 397mV-1 to 655mV-1, the most significant bit indicates ‘over threshold / spike’ which is convenient for visualization as unsigned and the number can be used interchangeably as signed or unsigned.

Inhibitory spikes can push the voltage below ‘-100mV’, but it should saturated here. Excitatory spikes can push the threshold above ‘-50mV’ but will be much, much less than the 50mV half full scale so there is no danger of overflow.

Spike Times

The time step is typically 1ms. Let us say there is a time window of +/-50ms by which I mean that a synaptic spike will have decayed to the resting potential (to the accuracy of 1 LSB) by 50ms, hence there is no point in calculating exponentials (whether for the membrane voltage or for STDP weight adjustments) if outside this period.

Spike times can be stored as 16-bit integers. Time will then roll over every 65.536 seconds. So if t=0.004 and a previous spike has a timestamp of 0.001 than we don’t know whether the spike occurred 0.003s ago (hence we need to adjust a weight) or 65.539s ago (in which case, we don’t). We could do a ‘garbage collection’ of sorts every 65.486s to set the time of every spike event older than 50ms to be 50ms ago. This would then keep us going OK for another 65.486s. This is an unwelcome overhead.

Synaptic Weights

Having calculated the new potential at a particular event time, we can then include the effect of that event…

When a neuron x fires, the downstream neuron y needs to be updated. Its voltage needs to be updated according to the strength of the weight.

We can make it easy by saying that the strength of the weight is measured in terms of the change in voltage of the downstream neuron. So we just have to add (for an excitatory neuron) or subtract (for an inhibitory neuron) the weight value to the voltage. The weights will be considerably less than 50mV (difference between the minimum -100mV and maximum=threshold -50mV). Weights can be unsigned 16-bit quantities for maximum sensitivity (better than 1310mV-1) for weight adjustment. It may be that the membrane voltage is adjusted by a half, quarter or eighth of the weight value (and then exponentially decayed). An exception is to have larger values for ‘training weights’ – synapses for which the pre-synaptic neuron is a training neuron can have it so that the weight is not scaled. In this case, a weight could then be large enough to force a spike on its own.


Some definitions of terms for what follows:

  • A network comprises groups of nodes connected together by matrices of synapses.
  • A node may be either an input or a neuron (outputs are at neurons).

For each group of neurons, we shall specify:

  • n_neurons: The number of neurons in the group.
  • n_type: Whether the group comprises inputs or neurons.


For each neuron, we shall specify:

  • event: flag to indicate the neuron has changed at this time step.
  • volt: voltage
  • tvolt: time of last change of potential
  • tspike: time of last spike

All these values can be 16 bits, apart from the 1-bit flag.

For input nodes, we only need event and tspike.

Matrix Connectivity

Typical second-generation networks will have the following types of connectivity:

  • Fully-connected
  • Convolution
  • Pooling

And it will support 1-, 2- or 3-dimensional objects.

For SNNs, neurons are often arranged randomly connected. I want to keep things simple, with a minimal amount of memory required to configure connections, so only ‘random’ matrices will be supported, of variable sparsity. Fully-connected is a special case of ‘random’ in which there are no connections randomly removed. And there is no concept of multi-dimensional objects.

Weights are one of two types:

  • per_syn: e.g. 128 weights for a matrix of from 16 nodes to 8 nodes, one for every synapse.
  • per_from: e.g. 16 weights for a matrix of from 16 nodes to 8 nodes.

The per_from format is useful for training inputs.

Instead of storing information about which specific neuron is connected to another, I want an algorithm to do this for us. This will free memory up to be available as synapses.

Consider a connection set from a group of 32 neurons to a group of 16. Fully-connected, each postsynaptic neuron would have 32 synapses and each presynaptic neuron would have 16 synapses. There would be a total of 512 synapses. If we want to have random sparse connectivity then we want to be sure that all neurons are still left with a least 2 synapses (to be useful). We do this by having a fixed number of synapses per neuron. A sparsity of 1/8 will mean there are 64 synapses in total: 32/8=4 per postsynaptic neuron and 16/8=2 per postsynaptic neuron. We need a function f_sparse(sparsity_index, layer, n_pre, n_post) that, given the ordinal number of the pre- and post-synaptic neurons potentially connected together, will return a true 1/8th of the time to say that there actually is a connection here. The sparsity index in this case with be 3 because 2-3=1/8. In order for the connectivity to be different for different sparse matrices in the overall network, a seed also needs to be given to each of these functions, unique to the connection set in question. The group number is used for this (whether directly or as a seed): f_seed(connection_set_number).

We also need a function f_unate(unateness_index, n_pre, n_post, seed) to indicate whether that synapse is excitatory or inhibitory. A unateness index of 3 means that 2-3=1/8 of the neurons that are present are inhibitory (0 means all are; the largest possible number means none are).

The definition of f_seed, index, f_sparsity, f_unate is not considered here.

So for any connection set, we need to specify:

  • n_pre: The pre-synaptic group identifier (number),
  • n_post: The post-synaptic group identifier (number),
  • seed: for randomization.
  • sparsity_index: How sparse the matrix is.
  • unate_index: To determine whether the connection is excitatory or inhibitory.


How much memory is required for network structures? I am not concerned with precise details here. This is just to give a general idea. Below is an example network. Whether this is a realistic network is not the point.

The network has 9 groups of nodes (labelled ‘A’ to ‘J’), including 3 input groups, 2 groups for supervised learning.


A group can either be a collection of neurons or a collection of inputs. With this fixed memory configuration, each group can connect to upto 4 other groups. Normally, neuron groups will just have 1 input and 1 output connection and input groups will just have 1 output connection.

The numbers 0…54 below refer to the word address in memory. Pointers refer to word addresses in memory.

groups = array([
[ 0  , { num_groups  :  9  }] ,
[ 1  , { ntype       :  inputs , num_nodes : 128  }] , # Group 'A'
[ 2  , { neuron_ptr  :  92  }] ,
[ 3  , { conn1_ptr   :    56 , conn_dir : out   }] , #     to 'D'
[ 4  , { conn2_ptr   :  null , conn_dir : null  }] ,
[ 5  , { conn3_ptr   :  null , conn_dir : null  }] ,
[ 6  , { conn4_ptr   :  null , conn_dir : null  }] ,
[ 7  , { ntype       :  inputs , num_nodes : 8  }] , # Group 'B'
[ 8  , { neuron_ptr  :  220  }] ,
[ 9  , { conn1_ptr   :    60 , conn_dir : out   }] , #     to 'E'
[ 10 , { conn2_ptr   :  null , conn_dir : null  }] ,
[ 11 , { conn3_ptr   :  null , conn_dir : null  }] ,
[ 12 , { conn4_ptr   :  null , conn_dir : null  }] ,
[ 13 , { ntype       :  inputs , num_nodes : 16  }] , # Group 'C'
[ 14 , { neuron_ptr  :  228  }] ,
[ 15 , { conn1_ptr   :    64 , conn_dir : out   }] , #     to 'F'
[ 16 , { conn2_ptr   :  null , conn_dir : null  }] ,
[ 17 , { conn3_ptr   :  null , conn_dir : null  }] ,
[ 18 , { conn4_ptr   :  null , conn_dir : null  }] ,
[ 19 , { ntype       :  neurons , num_nodes : 128  }] , # Group 'D'
[ 20 , { neuron_ptr  :  244  }] ,
[ 21 , { conn1_ptr   :    68 , conn_dir : out   }] , #     to 'E'
[ 22 , { conn2_ptr   :    56 , conn_dir : in    }] , #     from 'A'
[ 23 , { conn3_ptr   :    80 , conn_dir : in    }] , #     from 'H'
[ 24 , { conn4_ptr   :  null , conn_dir : null  }] ,
[ 25 , { ntype       :  neurons , num_nodes : 256  }] , # Group 'E'
[ 26 , { neuron_ptr  :  628  }] ,
[ 27 , { conn1_ptr   :    72 , conn_dir : out   }] , #     to 'G'
[ 28 , { conn2_ptr   :    60 , conn_dir : out   }] , #     from 'B'
[ 29 , { conn3_ptr   :  null , conn_dir : null  }] , #     from 'D'
[ 30 , { conn4_ptr   :  null , conn_dir : null  }] ,
[ 31 , { ntype       :  neurons , num_nodes : 16  }] , # Group 'F'
[ 32 , { neuron_ptr  :  676  }] ,
[ 33 , { conn1_ptr   :    76 , conn_dir : out   }] , #     to 'G'
[ 34 , { conn2_ptr   :    64 , conn_dir : in    }] , #     from 'C'
[ 35 , { conn3_ptr   :    84 , conn_dir : in    }] , #     from 'J'
[ 36 , { conn4_ptr   :  null , conn_dir : null  }] ,
[ 37 , { ntype       :  neurons , num_nodes : 2  }] , # Group 'G'
[ 38 , { neuron_ptr  :  682  }] ,
[ 39 , { conn1_ptr   :    72 , conn_dir : out   }] , #     from 'E'
[ 40 , { conn2_ptr   :    76 , conn_dir : out   }] , #     from 'F'
[ 41 , { conn3_ptr   :    88 , conn_dir : null  }] , #     from 'J'
[ 42 , { conn4_ptr   :  null , conn_dir : null  }] ,
[ 43 , { ntype       :  inputs , num_nodes : 8  }] , # Group 'H'
[ 44 , { neuron_ptr  :  706  }] ,
[ 45 , { conn1_ptr   :    80 , conn_dir : out   }] , #     to 'D'
[ 46 , { conn2_ptr   :  null , conn_dir : null  }] ,
[ 47 , { conn3_ptr   :  null , conn_dir : null  }] ,
[ 48 , { conn4_ptr   :  null , conn_dir : null  }] ,
[ 49 , { ntype       :  inputs , num_nodes : 8  }] , # Group 'J'
[ 50 , { neuron_ptr  :  730  }] ,
[ 51 , { conn1_ptr   :    84 , conn_dir : out   }] , #     to 'F'
[ 52 , { conn2_ptr   :    88 , conn_dir : out   }] , #     to 'G'
[ 53 , { conn3_ptr   :  null , conn_dir : null  }] ,
[ 54 , { conn4_ptr   :  null , conn_dir : null  }]

The matrices definitions associate the input group and the output group with the synapse weights and they define how the groups are connected:

  • Whether there is a connection between input node x and output node y.
  • Whether the connection is inhibitory or excitatory.
  • Whether the synaptic weight of the connection gets modified.
matrices = array([
   [ 55 , { num_mat    :  9  }] , # (Not needed)
   [ 56 , { seed       :  56  }] , # Matrix from A to D
   [ 57 , { from_ptr   :     1 , sparsity : eighth  , learn   : stdp
   [ 58 , { to_ptr     :    19 , unate    : eighth  , weights : per_syn
   [ 59 , { weight_ptr :   754 ,
   [ 60 , { seed       :  60  }] , # Matrix from B to E
   [ 61 , { from_ptr   :     7 , sparsity : full    , learn   : stdp  }] ,
   [ 62 , { to_ptr     :    25 , unate    : quarter , weights : per_syn  }] ,
   [ 63 , { weight_ptr :  2802  }] ,
   [ 64 , { seed       :  64  }] , # Matrix from C to F
   [ 65 , { from_ptr   :    13 , sparsity : full    , learn   : stdp  }] ,
   [ 66 , { to_ptr     :    31 , unate    : quarter , weights : per_syn  }] ,
   [ 67 , { weight_ptr :  4850  }] ,
   [ 68 , { seed       :  68  }] , # Matrix from D to E
   [ 69 , { from_ptr   :    19 , sparsity : sixteenth , learn : stdp  }] ,
   [ 70 , { to_ptr     :    25 , unate    : eighth  , weights : per_syn  }] ,
   [ 71 , { weight_ptr :  5106  }] ,
   [ 72 , { seed       :  72  }] , # Matrix from E to G
   [ 73 , { from_ptr   :    25 , sparsity : full    , learn   : stdp  }] ,
   [ 74 , { to_ptr     :    37 , unate    : quarter , weights : per_syn  }] ,
   [ 75 , { weight_ptr :  7154  }] ,
   [ 76 , { seed       :  76  }] , # Matrix from F to G
   [ 77 , { from_ptr   :    31 , sparsity : full    , learn   : stdp  }] ,
   [ 78 , { to_ptr     :    37 , unate    : quarter , weights : per_syn  }] ,
   [ 79 , { weight_ptr :  7666  }] ,
   [ 80 , { seed       :  80  }] , # Matrix from H to D
   [ 81 , { from_ptr   :    43 , sparsity : eighth  , learn   : fixed  }] ,
   [ 82 , { to_ptr     :    19 , unate    : eighth  , weights : per_from  }] ,
   [ 83 , { weight_ptr :  7698  }] ,
   [ 84 , { seed       :  84  }] , # Matrix from J to F
   [ 85 , { from_ptr   :    49 , sparsity : eighth  , learn   : fixed  }] ,
   [ 86 , { to_ptr     :    31 , unate    : eighth  , weights : per_from  }] ,
   [ 87 , { weight_ptr :  7706  }] ,
   [ 88 , { seed       :  88  }] , # Matrix from J to G
   [ 89 , { from_ptr   :    49 , sparsity : eighth  , learn   : fixed  }] ,
   [ 90 , { to_ptr     :    37 , unate    : eighth  , weights : per_from  }] ,
   [ 91 , { weight_ptr :  7714  }]

The nodes data container has the last spike time for each node and, for neurons rather than inputs, the voltage at the axon hillock and the time of the last change of the axon hillock voltage as well. The spike times of all nodes in a group are grouped together so that the format is the same whether the nodes are neurons or inputs.

nodes = array([
   [  92  , { tspike : init_tspike }] , # Neuron A 0
   [  93  , { tspike : init_tspike }] , # Neuron A 1
   [  94  , { tspike : init_tspike }] , # Neuron A 2
   [  95  , { tspike : init_tspike }] , # Neuron A 3
   [  96  , { tspike : init_tspike }] , # Neuron A 4
   [  97  , { tspike : init_tspike }] , # Neuron A 5
   [  98  , { tspike : init_tspike }] , # Neuron A 6
   [ 215  , { tspike : init_tspike }] , # Neuron A 123
   [ 216  , { tspike : init_tspike }] , # Neuron A 124
   [ 217  , { tspike : init_tspike }] , # Neuron A 125
   [ 218  , { tspike : init_tspike }] , # Neuron A 126
   [ 219  , { tspike : init_tspike }] , # Neuron A 127
   [ 220  , { tspike : init_tspike }] , # Neuron B 0
   [ 221  , { tspike : init_tspike }] , # Neuron B 1
   [ 222  , { tspike : init_tspike }] , # Neuron B 2
   [ 223  , { tspike : init_tspike }] , # Neuron B 3
   [ 224  , { tspike : init_tspike }] , # Neuron B 4
   [ 225  , { tspike : init_tspike }] , # Neuron B 5
   [ 226  , { tspike : init_tspike }] , # Neuron B 6
   [ 227  , { tspike : init_tspike }] , # Neuron B 7
   [ 228  , { tspike : init_tspike }] , # Neuron C 8
   [ 229  , { tspike : init_tspike }] , # Neuron C 9
   [ 230  , { tspike : init_tspike }] , # Neuron C 10
   [ 231  , { tspike : init_tspike }] , # Neuron C 11
   [ 232  , { tspike : init_tspike }] , # Neuron C 12
   [ 233  , { tspike : init_tspike }] , # Neuron C 13
   [ 234  , { tspike : init_tspike }] , # Neuron C 14
   [ 235  , { tspike : init_tspike }] , # Neuron C 15
   [ 236  , { tspike : init_tspike }] , # Neuron C 16
   [ 237  , { tspike : init_tspike }] , # Neuron C 17
   [ 238  , { tspike : init_tspike }] , # Neuron C 18
   [ 239  , { tspike : init_tspike }] , # Neuron C 19
   [ 240  , { tspike : init_tspike }] , # Neuron C 20
   [ 241  , { tspike : init_tspike }] , # Neuron C 21
   [ 242  , { tspike : init_tspike }] , # Neuron C 22
   [ 243  , { tspike : init_tspike }] , # Neuron C 23
   [ 244  , { tspike : init_tspike }] , # Neuron D 0
   [ 245  , { tspike : init_tspike }] , # Neuron D 1
   [ 246  , { tspike : init_tspike }] , # Neuron D 2
   [ 247  , { tspike : init_tspike }] , # Neuron D 3
   [ 248  , { tspike : init_tspike }] , # Neuron D 4
   [ 249  , { tspike : init_tspike }] , # Neuron D 5
   [ 250  , { tspike : init_tspike }] , # Neuron D 6
   [ 367  , { tspike : init_tspike }] , # Neuron D 123
   [ 368  , { tspike : init_tspike }] , # Neuron D 124
   [ 369  , { tspike : init_tspike }] , # Neuron D 125
   [ 370  , { tspike : init_tspike }] , # Neuron D 126
   [ 371  , { tspike : init_tspike }] , # Neuron D 127
   [ 372  , { tvolt  : init_tvolt  }] , # Neuron D 0
   [ 373  , { tvolt  : init_tvolt  }] , # Neuron D 1
   [ 374  , { tvolt  : init_tvolt  }] , # Neuron D 2
   [ 375  , { tvolt  : init_tvolt  }] , # Neuron D 3
   [ 376  , { tvolt  : init_tvolt  }] , # Neuron D 4
   [ 495  , { tvolt  : init_tvolt  }] , # Neuron D 123
   [ 496  , { tvolt  : init_tvolt  }] , # Neuron D 124
   [ 497  , { tvolt  : init_tvolt  }] , # Neuron D 125
   [ 498  , { tvolt  : init_tvolt  }] , # Neuron D 126
   [ 499  , { tvolt  : init_tvolt  }] , # Neuron D 127
   [ 500  , {  volt  : init_volt   }] , # Neuron D 0
   [ 501  , {  volt  : init_volt   }] , # Neuron D 1
   [ 502  , {  volt  : init_volt   }] , # Neuron D 2
   [ 503  , {  volt  : init_volt   }] , # Neuron D 3
   [ 504  , {  volt  : init_volt   }] , # Neuron D 4
   [ 623  , {  volt  : init_volt   }] , # Neuron D 123
   [ 624  , {  volt  : init_volt   }] , # Neuron D 124
   [ 625  , {  volt  : init_volt   }] , # Neuron D 125
   [ 626  , {  volt  : init_volt   }] , # Neuron D 126
   [ 627  , {  volt  : init_volt   }] , # Neuron D 127
   [ 628  , { tspike : init_tspike }] , # Neuron E 0
   [ 629  , { tspike : init_tspike }] , # Neuron E 1
   [ 630  , { tspike : init_tspike }] , # Neuron E 2
   [ 631  , { tspike : init_tspike }]   # Neuron E 3

And so on.

The weights are listed in order of source and destination nodes, dependent on type. For sparsely-connected matrices, the pseudo-random algorithm will allow the right source and destination nodes to be worked out for each weight word.

In the database, the weights finish off with…

   [ 7666 , { weight : 0 }] , # From F0  to G0
   [ 7667 , { weight : 0 }] , # From F0  to G1
   [ 7668 , { weight : 0 }] , # From F1  to G0
   [ 7669 , { weight : 0 }] , # From F1  to G1
   [ 7670 , { weight : 0 }] , # From F2  to G0
   [ 7671 , { weight : 0 }] , # From F2  to G1
   [ 7672 , { weight : 0 }] , # From F3  to G0
   [ 7673 , { weight : 0 }] , # From F3  to G1
   [ 7674 , { weight : 0 }] , # From F4  to G0
   [ 7675 , { weight : 0 }] , # From F4  to G1
   [ 7676 , { weight : 0 }] , # From F5  to G0
   [ 7677 , { weight : 0 }] , # From F5  to G1
   [ 7678 , { weight : 0 }] , # From F6  to G0
   [ 7679 , { weight : 0 }] , # From F6  to G1
   [ 7680 , { weight : 0 }] , # From F7  to G0
   [ 7681 , { weight : 0 }] , # From F7  to G1
   [ 7682 , { weight : 0 }] , # From F8  to G0
   [ 7683 , { weight : 0 }] , # From F8  to G1
   [ 7684 , { weight : 0 }] , # From F9  to G0
   [ 7685 , { weight : 0 }] , # From F9  to G1
   [ 7686 , { weight : 0 }] , # From F10 to G0
   [ 7687 , { weight : 0 }] , # From F10 to G1
   [ 7688 , { weight : 0 }] , # From F11 to G0
   [ 7689 , { weight : 0 }] , # From F11 to G1
   [ 7690 , { weight : 0 }] , # From F12 to G0
   [ 7691 , { weight : 0 }] , # From F12 to G1
   [ 7692 , { weight : 0 }] , # From F13 to G0
   [ 7693 , { weight : 0 }] , # From F13 to G1
   [ 7694 , { weight : 0 }] , # From F14 to G0
   [ 7695 , { weight : 0 }] , # From F14 to G1
   [ 7696 , { weight : 0 }] , # From F15 to G0
   [ 7697 , { weight : 0 }] , # From F15 to G1
   [ 7698 , { weight : 0 }] , # From H0  to all D
   [ 7699 , { weight : 0 }] , # From H1  to all D
   [ 7700 , { weight : 0 }] , # From H2  to all D
   [ 7701 , { weight : 0 }] , # From H3  to all D
   [ 7702 , { weight : 0 }] , # From H4  to all D
   [ 7703 , { weight : 0 }] , # From H5  to all D
   [ 7704 , { weight : 0 }] , # From H6  to all D
   [ 7705 , { weight : 0 }] , # From H7  to all D
   [ 7706 , { weight : 0 }] , # From J0  to all F
   [ 7707 , { weight : 0 }] , # From J1  to all F
   [ 7708 , { weight : 0 }] , # From J2  to all F
   [ 7709 , { weight : 0 }] , # From J3  to all F
   [ 7710 , { weight : 0 }] , # From J4  to all F
   [ 7711 , { weight : 0 }] , # From J5  to all F
   [ 7712 , { weight : 0 }] , # From J6  to all F
   [ 7713 , { weight : 0 }] , # From J7  to all F
   [ 7714 , { weight : 0 }] , # From J0  to all G
   [ 7715 , { weight : 0 }] , # From J1  to all G
   [ 7716 , { weight : 0 }] , # From J2  to all G
   [ 7717 , { weight : 0 }] , # From J3  to all G
   [ 7718 , { weight : 0 }] , # From J4  to all G
   [ 7719 , { weight : 0 }] , # From J5  to all G
   [ 7720 , { weight : 0 }] , # From J6  to all G
   [ 7721 , { weight : 0 }]   # From J7  to all G
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Representation of the People

TL;DR: see bottom of post

Over time, the electorates of Western societies have become more representative of society as a whole. For example, prominent steps in the UK were:

But this says nothing about how representative the representatives themselves are of their electorate. The UK House of Commons chamber in Parliament has gradually become more representative over the last 50 years but there is still a very long way to go.

Prominent attention has been given to the under-representation of minorities such as race and sexual orientation which now have a better level of representation than women (a case of under-representation of a majority). There have been active measures to dress the gender imbalance – parties having women-only shortlists for parliamentary candidates.

But we know we still have far to go. We know than alumni of Eton and Oxford University and students of ‘PPE’ are over-represented in parliament but just how over-represented are they? What other sectors of society are over-represented, and to what extent?

The table below charts how unlikely it is that various sectors of society would have the number of Members of Parliament (MPs) that they do have in the House of Commons if MPs were randomly selected from the electorate. For example, there are 16,000 barristers within the UK of adult population of 52,000,000 so one person in 3250 is a barrister. But there are 38 barristers in the 650-member House of Commons – one in 17.

If p is the probability of picking a barrister randomly from the entire UK adult population then the probability of getting exactly k barristers in n trials is given by the Binomial probability mass function:

p(x=k) = pkp(n-k)n! /k!/(n-k)!

Plugging the numbers in (k=38 and n=650 and p=16,000/52,000,000) we get to the vanishingly small probability of there being 38 barristers within the House of Commons if people were uniformly selected to be an MP from across the entire UK adult population of:

p(x=38) = 1.4 x 10-72

When dealing with such small numbers, it is more convenient to deal with ‘surprisal’ – the negative log probability – rather than probabilities directly. The larger the value of this ‘surprise factor’ means that the circumstance is further away from that expected from random (‘fair’) chance. For the barristers, this results in a surprise factor of 238.6. In Excel-speak, this is result is calculated by:


If people were uniformly selected to be an MP from across the entire UK adult population, the mean number of barristers would be 0.2. Obviously, there can only be an integer number. The probability of getting the expected mean number of MPs would be:

p(x=0) = 0.819

That this is so much more likely than p(x=38) shows how skewed the composition of the House of Commons is.

The probabilities can be surprising in themselves. Although the probability of being an Oxford graduate is much higher than that of being a barrister, the sheer number (114) of Oxford graduates in parliament produces a much higher surprise factor: 473. Compared to a surprise factor of 238 for barristers, this may not seem that much but 473 is equivalent to a probability of 3 x 10-143! Even ‘astronomically small’ does not seem an adequate description of this number.

In the table, I quantify this skewed composition by various categories. I have used the convention that positive surprise factors show that a group is over-represented in parliament whereas negative surprise factors indicate that group being under-represented in parliament. The numbers have been obtained from various sources and will therefore not be consistent, but discrepancies will make negligible difference to the interpretation of the results, partly because of the logarithmic nature of the ‘surprise’ metric.

Class Type no.* No. MPs surprise fairer no. MPs**
18+ 52,000,000* 650
18-year olds 766,000*
Profession Councillor 18,912 82 586.1 14
Graduate Oxford 3,200 114 473.4 29
School Private 53,620 228 316.0 117
Profession Lobbyist 141 24 299.2 6
Education University 411,860 585 295.2 464
Profession Barrister 16,000 38 238.6 13
Profession Solicitor 140,000 51 183.9 25
Graduate Cambridge 3,497 59 181.5 30
School Eton 260 20 105.4 14
Graduate LSE 1,603 23 66.7 23
Gender Male 26,000,000 442 67.1 442**
Profession Journalist 73,000 18 56.4 20
Age 50-59 8,852,000 197 54.8 207
Age 40-49 8,634,000 190 50.9 204
School Millfield 200 5 20.0 13
Race White 44,720,000 598 20.3 629
Sexuality Hetero. 45,240,000 603 20.1 633
Graduate Edinburgh 6,221 17 15.3 38
Graduate Glasgow 5,105 15 14.9 35
Graduate Hull 4,533 14 14.8 33
Graduate Durham 4,555 14 14.7 33
Age 60-69 7,072,000 114 10.4 178
Age 30-39 8,704,000 102 -4.9 32
School Selective 167,000 124 -6.8 27
Sexuality LGBT+ 45,240,000 47 -20.1 17
Race Non-white 44,720,000 52 -20.3 21
Age Over 70 8,515,000 28 -70.7 45
Age 18-29 1,0299,000 14 -141.0 30
School Comprehensive 545,380 293 -144.2 352


  • *: Number within the sample. In the case of schools/education, I use the number within the annual cohort of 766,000 18-year olds. This will overestimate the number of people in the entire population because student numbers have increased significantly in the last 20 or so years. For all the other criteria, I use the number within the entire UK adult population.
  • **: Number of MP if the under- or over-representation was to the same extent as gender, i.e. the surprise factor is about 67.

Most over-represented are those MPs who were formerly councillors. But this is not really surprising or unfair – local government is a junior league of government and obvious training ground for higher-level public service. More concerning is the number who were lobbyists.

The age groups should not be surprising or concerning: we would like our politicians to have had some experience before entering the House of Commons and we would expect many over 70 to be retired.: over-70s and under-40s; retirement and have MPs that have some experience.

As expected, Oxford graduates and those educated privately (and particularly at Eton) are significantly over-represented. Comprehensive schools are as under-represented as Eton is over-represented.

Oxford is extraordinarily over-represented; Cambridge only considerably so! Other English universities start coming in at a surprise factor of 15. Premier Scottish universities are also around this level so there is no obvious skewing here.

But the most significant thing to be drawn from this table is the huge under-representation of those who did not go to university at all.


Notwithstanding the non-graduate representation, the degree subjects studied by MPs and away from engineering, architecture and the biological sciences (but not maths or the physical sciences) and, surprisingly, also away from business and administration degrees.


If we find the under-representation of women in parliament unacceptable to the extent that affirmative action is taken then we should also be accepting that actions should be taken to redress the under-representations of other groups even less well represented. The last column shows the number of MPs for each group if they were under- or over-represented to the extent that women are. The number for graduates is 464. If the number of graduates were reduced from 585 to 464, as an initial move to redress the imbalance, there would still be an ‘unacceptible’ number of graduates and maybe it could be argued that some sort of action after reaching that threshold was not necessary. But it is difficult to argue against action beforehand. A party banning graduates getting onto new candidate shortlists seems absurd whereas a ban on Oxford graduates to reduce their number from 114 to 29 seems more acceptible (some would say particularly so when reviewing who they are)! Perhaps one solution is to only allow voting in proportion to this adjusted over-representation; thus, randomly, only 29 of 114 of MPs would be allowed to vote in any parliamentary sitting!

Some of the sources:

TL;DR: Progress is being made on making parliament more representative of the electorate as a whole but it is slow. The privately-educated and alumni of Oxford are among the most over-represented groups but this was to be expected. It is the difference in representation between university graduates and those who did not go to university that is the most significant anomaly – far more pronounced than gender inequality, for example. If positive discrimination is justified for redress the gender balance, why not also for education?

P.S.: contains more recent data.


Postscript, May 2019

A topical postscript: the above is about the backgrounds of the 650 UK Members of Parliament. What about the top job?

Here’s the background of former UK Prime Ministers since 1964…

Prime Minister School University Degree Occupation
Edward Heath grammar Oxford PPE civil servant
Harold Wilson grammar Oxford PPE lecturer
James Callaghan grammar (none) (none) tax inspector
Margaret Thatcher grammar Oxford Chemistry scientist
John Major grammar (none) (none) banking
Tony Blair private Oxford Law law
Gordon Brown state Edinburgh History lecturer
David Cameron Eton Oxford PPE politics
Theresa May grammar Oxford Geography banking

And here’s the background of the contenders to be the next Prime Minister, in rough order of likelihood…

Contender School University Degree Occupation
Boris Johnson Eton Oxford Classics journalism
Dominic Raab grammar Oxford Law law
Michael Gove scholarship Oxford English journalism
Andrea Leadsom grammar Warwick Pol. Sci. banking
Sajid Javid comp Exeter Econ./Pol. banking
Jeremy Hunt Charterhouse Oxford PPE management
Penny Mordaunt state Reading Philosophy PR
Rory Stewart Eton Oxford PPE foreign office
Liz Truss state Oxford PPE accountant
Amber Rudd Cheltenham Edinburgh History banking
Matt Hancock private Oxford PPE economist
Priti Patel state Keele Economics politics
Esther McVey state Queen Mary Law media presenter
Graham Brady grammar Durham Law PR

Spot any pattern?


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The Shape of Politics

Many people have tried to create some conceptual space in order to map the positions of particular policies, particular persons or particular parties relative to others.

The Line

By far the most prevalent of these is the left-right axis. The political terms ‘Left’ and ‘Right’ appeared during the French Revolution when members of the National Assembly divided into supporters of the king, sitting on the president’s right (‘the party of order’: the ‘conscientious defenders of the constitution’) and supporters of the revolution on his left (‘the party of movement’ : the ‘innovators’). Centrists (a.k.a. ‘moderates’) held intermediate positions.

Today, one can commonly define oneself as being somewhere on a line (the ‘political spectrum’) that runs from the Far Left to Far Right. At the extremes, the Far Left can be considered to be of revolutionary ‘extreme movement’ but the Far Right is generally associated with Fascists rather than ‘Ultra-Conservative’ defenders of the existing order, such as in many Middle East nations.

Square I: The Nolan Chart

Perhaps such a linear categorization of political position is too, well, one-dimensional. A number of people have tried to create a ‘political compass’ that points to political positions in a way that is more illuminating.

For example, David Nolan’ created a chart which inherits the traditional left-right (‘Progressive’ to ‘Conservative’) spectrum but it adds an orthogonal ‘Authoritarian’ to ‘Libertarian’ axis to form a square. This new axis covers the degree to which a government should be able to impose its will upon its citizens – whether the decisions that need to be made in a society are ‘top-down’, from a few in command (Authoritarian in the extreme), or ‘bottom-up’, with each individuals individually making decisions for themselves (Anarchic in the extreme). Hans Eysenck called these axes the ‘left-right’ and the ‘tough-tender’ respectively.

A political position can now be pinpointed with Cartesian co-ordinates, with, for example, Authoritarian Fascists now sitting in different part of the space to Ultra-Conservatives.

The ‘Political Compass’ website provides fascinating examples of Nolan charts, some of which are also shown below. Firstly, here are some examples from some recent major national elections (Note that the Authoritarian/Libertarian axes is flipped upside-down compared with some Nolan charts.)…

Here is a Nolan chart for the US presidential election of 8 November 2016

Here is a Nolan chart for the French presidential election (first round) of 23 April 2017

Here is a Nolan chart for the UK election of 8 June 2017

And here is a Nolan chart for the German election of 24 September 2017

Then, below is a Nolan chart for a country-by-country comparison within the European Union based on 2012 data…

And finally, the Nolan chart below indicates the position of US states based on their senators’ voting patterns for a selection of states: blue circles show states where both senators are Democrat (CA, IL, MI, MA, NY, PA), orange circles show states where both senators are Republican (AL, KS, TX) and white Florida has one of each.

Square II: The Pournelle Chart

And there are other, similar, 2-dimensional charts such as by Jerry Pournelle, in which the axes represent:

  1. ‘Attitude toward the State’, running from ‘the state is evil’ preference of individual freedom through to ‘statism’ (‘state worship’), and
  2. ‘Attitude toward planned social progress’, running from complete confidence in state planned social progress (called ‘rational’!) through to complete scepticism of such an approach as being naïvely utopian (termed ‘irrational’!).

[picture credit]

The Vosem Cube

A third axis can be added, for greater refinement. Whereas the Nolan Chart has the two axes:

  1. the economic axis, ranging from ‘Progressive’ to ‘Conservative’, and
  2. the personal axis, ranging from ‘Authoritarian’ to ‘Libertarian’.

the Vosem chart adds third axis for greater refinement, making it a cube. The first two axes are modified slightly from the Nolan chart so that we end up with:

  1. the economic axis, ranging from ‘Liberal’ to ‘Conservative’,
  2. the personal axis, ranging from ‘Communitarian’ to ‘Libertarian’, and
  3. the governmental axis, ranging from ‘Anarchism’ to ‘Monarchism’.

(‘Vosem’ is Russian for eight, there being 8 vertices of the cube.)

[picture credit]

A US-based Vosem chart below describes the eight corners of the cube as:

  • back lower right: conservative
  • back upper right: authoritarian
  • front lower right: traditional societies
  • front upper right: totalitarian
  • back lower left: libertarian
  • back upper left: New Labour
  • front lower left: anarcho-syndicalist
  • front upper left: liberal

In this cube:

  • The left-right axis is the cultural axis, from the permissive left to the restrictive right.
  • The up-down axis is the fiscal axis, from active government at the top to minimal government at the bottom.
  • The front-back axis is the corporate axis, from pro-business at the back to anti-corporate at the front.
  • The square at the back is the Nolan chart, with ‘progressive’ cast as ‘New Labour’.

Triangle: The Rummel Chart

Three parameters do not need to be represented by a cube if they are proportions – a triangle can be used – a ternary plot. Rudolph Rummel proposed such a plot in which we can pinpoint a political position in terms of the three coefficients L, T and A in the range 0 to 1 that represent the Libertarian (democratic), Socialist (Totalitarian, Communist) and Authoritarianism (Dynastic/Monarchical) factors. L+T+A=1 because the three parameters are proportions.


[picture credit]

A New Triangle: Liberté, Egalité, Fraternité

Paul Archer has proposed a new ternary plot where the parameters are socialism, liberalism, and conservatism and also onto the values of freedom, equality and belonging respectively:

“in order to think about whether we can find wisdom in each political tradition and whether we are allowed to want freedom and equality and belonging.”

These values are of course better known in the form of the French Revolutionary motto ‘Liberté, Egalité, Fraternité’.

Expounding on the three corners in turn:

  • liberalism (‘with a small l’) is about the freedom of the individual to be different from others. Obviously, it is associated with Liberté. There is freedom to choose to do different things, have different things and say different things (freedom of speech). It could perhaps be called ‘individualism’. Freedom from autocracy is achieved by the pluralism of the market.
  • socialism (‘with a small s’) is about equality – associated with Egalité. In order to protect the welfare of working class people from the interests of the rich, wealth is held in common (common-wealth) through public ownership, with central planning required to manage political affairs.
  • conservatism(‘with a small c’) is sceptical about change (if being absurdly reductive, it is about conserving the status quo). The society we live in today is fragile and must be protected. It has taken centuries to develop its successful institutions that could be so easily destroyed by radical change. We should therefore err on the side of caution and generally maintain existing traditions in governance and culture. Social cohesion is maintained through the ‘glue’ of shared values, customs and history. Individuals have a sense of belonging– a brotherly connectedness to others. Hence it is associated with the most problematic component of the Tricolore – Fraternité. It is in this corner that so-called primitive societies lie, as well as deeply religious ones (note the etymology of the word ‘religion’: from Latin ‘religare’ meaning ‘to bind’). Modern society has evolved from these small hierarchical societies and developed through the nation-state. Hence it is also associated with nationalism and regionalism. 


Note that democracy does not get a mention here. All three corners can be democratic. The triangle represents the landscape in which democracies can sit. Wherever in the triangle can be democratic. Indeed, the triangle’s fundamental values map neatly onto the main left-of-centre / centre / right-of-centre set of main political parties in many countries. For example:

A political position can be mapped onto anywhere on this triangle by the coordinates of s, l and c representing the degree of socialism, liberalism and conservatism respectively (the coordinates are ratiometric such that s+l+c=1). For example, the point on the edge of the triangle midway between the socialism and liberalism corners (near the SL text) is at s=0.5, l=0.5, c=0.0.

So, we don’t have to choose exclusively between equality, freedom and belonging. There are merits in all three and political positions are a mixture of them. A political party can sit at different points in the triangle on different issues. The same is true of any individual person. Most parties and most of us will be closer to the SLC text in the centre of the triangle than to any of the corners. ‘There is more that unites us than divides us’.

Navigating around this triangle:

  • Moving from C to SL (decreasing c from 1 to 0) the boundary around ‘us’ expands to cover all humans. Socialism is internationalist and liberalism favours globalisation whereas conservatism still stands by the proven political unit of the nation-state. The practice of religion also declines.
  • Moving from L to SC (decreasing l from 1 to 0) sees the individual disappear into the crowd that can become stifling and oppressive – whether it is the uniformity of socialist workers or the hierarchy of traditional roles. Society going in that direction moves from dynamism to rigid forms of governance.
  • Moving from S to LC (decreasing s from 1 to 0) sees inequality rise (and the Gini index increase from zero), whether it is the traditional inequalities of conservatism or the more modern inequalities of the liberal free market. There is also a move away from the idealism of socialism of how people should be towards how people actually are: relying on empathy to bind conservative societies together or relying on personal self-interest to drive liberal ones.

The Tetrahedron: Liberté, Egalité, Fraternité – or Autocracy

Extending this Tricolour idea further, we can add another axis, converting the triangle into a tetrahedron (triangle-based pyramid) in which the Authoritarianism of the Rummel chart is added.

The existing triangle forms the base which represents pure, direct democracy. Pure Liberté, pure Egalité and pure Fraternité can all be democratic on their own. From anywhere in the triangular, as we move towards the ‘Autocracy’ apex, others make more and more decisions on behalf of people. Of course, at the very apex, one person makes the big decisions for everyone else.

Note that, viewed from a particular angle, the tetrahedron looks like a triangle with socialism, libertarianism and autocracy in its corners – exactly as the Rummel chart is.


Left, Right and the So-Called Centre

If we take the triangle and look at it side-on with the L corner pointing towards us, we see the Left, the Centre and the Right-leaning parties sat on the classic Left-Right spectrum.


From around 1980 many conservative political parties started moving away from their ‘one-nation conservatism’ / Christian Democratic positions towards the free market and individualism (reducing c and increasing l). Also from around 1980, inequality has been stagnant or increasing, after many years of improvement beforehand.

In the 1990s, parties of the Left such as New Labour also started moving towards the free market and individualism (reducing s and increasing l). The result has been a move towards L for all realistic governing options for the electorate, with relatively little to choose between left-of-centre and right-of-centre parties.

A party of the Left can think it will get more votes by moving towards the centre; some voters to their left may then choose not to vote for anyone but they will not move over the Centre to vote for the right. Symmetrically, the same applies to a party of the Right.

But this classic left-right spectrum view of politics hides that fact that what we think of as the centre (crowded as it is with left-of-centre, centrist and right-of-centre parties) is not at the real centre of politics! It is in a corner – the L corner. The actual centre of the triangle is at SLC. The distance from S to C is no further than from S to L – in fact, it is the same. Voters are quite capable of bypassing the Centre ground.

A Re-Orientation

So there is a whole axis, orthogonal to the Left-Right spectrum, running from Liberal L to the space around SC that we can be blissfully unaware of. A move away from Liberal democracy to SC is a move to ‘illiberal democracy’ – otherwise disparagingly called ‘populism’.

The concerns of those at SC – the inequality issue of being ‘left behind’ combined with being in a changing community with a disappearing sense of community (belonging) are a long way away from L and hence are seen as extreme by the political mainstream at L and dismissed accordingly. In fact, the political leaders are actually at AL, a significant way up the autocracy scale. And hence we get this classic antipathy between ‘Populism’ and the ‘Liberal Elite’ (or

‘undemocratic liberal’). AL is a long way from SC. It is in fact diametrically opposite. There is incomprehension instead of sympathy. And thus we get that seminal pair of election-loser moments: UK Prime Minister Brown’s ‘that bigoted woman’ moment and Hillary Clinton’s ‘basket of deplorables’.

Perhaps politics today is flipping over to a new axis. The Left/Right dichotomy is changing to a Liberal/Populist one – with dramatic consequences for political parties on the old alignment.

Demonizing Others

With the traditional Left-Right spectrum, people tend to conceptually push those with significantly different values from themselves off to the extremes where autocracies lie.

We demonize them, reject what they say without even listening and probably call them Fascists.

But with the pyramid, we recognise that there are 4 directions that those with different political opinions may be and we see that ‘more socialist’, ‘more conservative’ and ‘more liberal’ are in very different directions to the ‘more autocratic’. We will not demonize them and start to listen. Getting into the mind of others is both moral and strategic:

‘Why does the other think that way?’

As Jonathan Haidt has said:

‘A good place to look for wisdom is in the minds of your opponents’

The New Centre

In his 1978 article ‘How to Be a Conservative-Liberal-Socialist’, the Polish philosopher Leszek Kołakowski maintained that Conservatism, Liberalism and Socialism are not mutually exclusive.

Kołakowski said:

A Conservative Believes:

  1. That in human life there never have been and never will be improvements that are not paid for with deteriorations and evils; …
  2. That we do not know the extent to which various traditional forms of social life–families, rituals, nations, religious communities–are indispensable if life in a society is to be tolerable or even possible. …
  3. That the idée fixe of the Enlightenment–that envy, vanity, greed, and aggression are all caused by the deficiencies of social institutions and that they will be swept away once these institutions are reformed– is not only utterly incredible and contrary to all experience, but is highly dangerous. …

A Liberal Believes:

  1. That the ancient idea that the purpose of the State is security still remains valid. …
  2. That human communities are threatened not only by stagnation but also by degradation when they are so organized that there is no longer room for individual initiative and inventiveness. …
  3. That it is highly improbable that a society in which all forms of competitiveness have been done away with would continue to have the necessary stimuli for creativity and progress. …

A Socialist Believes:

  1. That societies in which the pursuit of profit is the sole regulator of the productive system are threatened with as grievous–perhaps more grievous–catastrophes as are societies in which the profit motive has been entirely eliminated from the production-regulating forces. …
  2. That it is absurd and hypocritical to conclude that, simply because a perfect, conflict-less society is impossible, every existing form of inequality is inevitable and all ways of profit-making justified. …
  3. That the tendency to subject the economy to important social controls should be encouraged, even though the price to be paid is an increase in bureaucracy. …

As far as I can see, this set of regulative ideas is not self-contradictory. And therefore it is possible to be a conservative-liberal socialist. This is equivalent to saying that those three particular designations are no longer mutually exclusive options.

No-one is 100% socialist, 100% conservative or 100% liberal. We all have some mixture of these values, probably with most of us towards the centre of the triangle rather than off towards a corner.

We also need to get the right balance between the democratic extremes of anarchism (everyone making decisions for themselves) and autocracy (one person making the decisions on behalf of everyone else). This puts most people somewhere around the centre of the tetrahedron. We can have Liberté, Egalité, Fraternité and Democracy.

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New Processes at Work

Automation, Education and Work, Part 2

This is the second of three parts of the talk ‘Automation, Education and Employment’. In the ‘first part’:

  • I considered how change is driven by both new technology and new processes as a result of technology, and
  • I looked at some of the technology emerging now.

Now in part 2:

  • I consider new processes that have recently emerged, and
  • I examine a number of work areas with regard to these new processes.


New Process: Self-Driving Cars

It is no secret that the new artificial intelligence technology is being applied to self-driving cars, for example, to recognise objects ahead (see the picture in part 1) to make decisions how to steer and brake. A self-driving car is really just a robot whose job is to carry something from A to B – where that something is you. Here, I’m not going to talk about the technology of self-driving cars, but look at how we will use them in different ways – a new process.

At the moment, there are many ways of getting from A to B:

  • We can drive our own car
  • We can use a car we lease,
  • We can hire a car,
  • We can book a minicab,
  • Use Uber, or
  • Hail a cab off the street.

And these are just the options if we want to travel alone. If we don’t mind travelling with strangers there‘s also:

  • Hitch-hiking
  • Car-sharing
  • Shared taxis
  • Chartered coaches, trains, planes
  • Scheduled services (bus, coach, train…)

There are many trade-offs involved in making the choice, not least cost.

I am warning against making the mistake that we just substitute old technology for new. If everyone who currently has a car suddenly had a viable self-driving car tomorrow, there would be fewer road deaths and injuries, less hold-ups and we could use the journey time more productively.

But self-driving cars change the whole process of getting from A to B. In principle, everyone’s car could drop them off at work in the morning and, instead of sat in the work car park all day, go off and do some Uber work, providing some extra income for you. But this is true for everyone else with a self-driving car. This is going to force Uber rates down very low. But in so many cases, it is not going to be worthwhile having you own car anyway.

There can be a shift from car ownership to using a contract car service. Just as you can choose a tariff for a mobile phone contract based on expected usage, you can select a car service plan (or you can PAYG instead). This might provide an inclusive number of local and/or long-distance miles. There might be some gold/silver/bronze level of service which would determine how long you would need to wait. You could pay for the option that provided you with a maximum 3-minute delay to get a car to your door between 7am and 8am work-day mornings and between 5pm and 6pm in the evening; most days, the car would be waiting on your drive for you. All this organization of where cars should be when would, of course, be coordinated by some artificial intelligence algorithm. Some people would still own cars (flashy status-symbol cars) but a very large number would just use a service that provided them with a reliable way of getting from A to B in the right format (small cab, pickup, van) and weren’t concerned about the badge on the front of the car. The services could in fact be provided by the manufacturers themselves. Their interest would be in minimizing the cradle-to-grave costs of car miles rather than minimizing up-front price and trying to tie you into expensive after-sales costs.

On longer journeys, self-driving vehicles will organize themselves into a string of wirelessly-connected vehicles, travelling closely together so as to improve energy efficiency from slipstreaming. Previously, a string of vehicles would have been called a ‘train’ or ‘caravan’ but the terminology used for a string of self-driving cars is a ‘platoon’. On trunk routes, vehicles can join and leave the platoons at the points where peoples’ journeys converge and diverge. Changes from ‘pod’ cars to ‘carriage’ buses can be coordinated so that the transfer time is only a few minutes. Just a few types of vehicle can provide the whole range of means of transport currently served by vehicles from cars to trains. Self-driving vehicles can change the whole model of how we get from A to B, significantly reducing our transport costs and worries as well as making journeys safer and more enjoyable.

Safe Jobs and Vulnerable Jobs

In the very-frequently cited ‘The Future of Employment’ paper by Frey and Osborne, there is a graph (shown below) that indicates how vulnerable different occupations are to the new technology.

The horizontal scale runs from 0.0 to 1.0 where 0.0 represents completely safe and 1.0 represents completely vulnerable. Jobs are categorized into occupation groups. On the safe left-hand side there are the large majority of managerial, engineering, health worker and teacher jobs. On the vulnerable right-hand side there are the large majority of service, sales, retail, office administration and transportation jobs. But that states the conclusions far too simply.

Calum Chace coined the clumsy term ‘unforecast’ for a postulated scenario that looks like a prediction about the future but where the point is not to make the assertion ‘I think this will happen’ (it invariably eventually turns out to not be so) but to get you to think about how the future may be.

I provide some unforecasts here. They are to get you to think about how things may be different from the stereotypical vision of the future full of anthropomorphic robots working everywhere. The nature of the work will change as a result of new technologies and processes, regardless of where on the vulnerability spectrum the current jobs lie.

Unforecast 1: Transportation

The first unforecast looks at transportation – a ‘vulnerable’ occupation.

For long-distance transportation, we are presented with the vision of platoons of self-driving trucks. And drones are offered as the worker-free solution to local deliveries. But currently, drones are a number of orders of magnitude more expensive per ton mile than trucks. And there will be legal problems managing them. And it will only take a handful of drone terrorist attacks to put their usage back for years.

Imagine that a delivery depot in a particular town currently employs 8 van drivers serving the town and its surrounding villages. The stereotypical idea is that they will be replaced by 8 self-driving vans plus 8 anthropomorphic robots to deliver the package from the van to the bed.

In the long term, this completed solution may be possible (whether this is desirable is an entirely different consideration). But in the medium-term, it will still be cheaper to employ someone to do the last 10 metres (on minimum wage). I imaging the following scenario:

  • There are just 2 delivery people doing the work previously done by 8.
  • A self driving van takes them out to the start of the delivery route.
  • They make a delivery at the drop-off address.
  • Whilst the van is moving to the next destination, the worker can load up a small, short-range drone to take a small, light parcel to its destination close by.
  • Meanwhile 7 other vans are on the road going to various way-points. A central algorithm works out an optimum route.
  • The vans park at various rendezvous points. The ‘driver’ swaps vans, maybe swapping some parcels too.
  • As well as having drones, the worker may be assisted by a ‘robo-trolley’ – something to carry bulky items so that there is no risk of back injury to the worker.

Thus, the workers spend all their time out performing delivery duties. They do not lose time just sat in the van doing nothing except getting from stop A to stop B and going back and forth to the depot.

From the standpoint of today, the job the worker is doing is very vulnerable – 75% of the delivery jobs have disappeared. But the role has changed, not least in being instructed what to do and when by an AI algorithm.

For long-distance haulage, it is a similar story. There are productivity gains from not having drivers getting paid for being sat in cabs for hundreds of miles a day. The trucks mainly travel in platoons on trunk routes, getting to distribution depots right next to the freeway junction, rendezvousing with ‘local’ drivers at truck stops.

Unforecast 2: Caring for the Elderly

Societies around the world are facing the problems of dealing with an ageing population. It is expected that there will be a large increase in the amount of physical and mental health care for the elderly. This will mean an increase in the number of jobs. Current jobs in this sphere will be secure. That is the expectation.

But people are working on robots to help in this field. Here, below, we have the RI-MAN robot being tested on the carrying of a person:

Being Japanese, the robot is very humanoid (I find this Japanese trait rather disturbing) with its face with big friendly eyes. The media reinforce this stereotypical view of robots.

People generally envisage a robot doing something that humans can do, in the same way that a human would do it. This is the case here in this example above. But is there a different way of doing things – either easier to automate or to provide a better solution? Is this the technology that is really needed? For sure, AI can improve on the currently technology to move patients around a hospital – a trolley. We might envisage AI-based improvements to a standard hospital trolley – a ‘robo-trolley’.

Where possible, the right solution is not to have robots physically help the elderly but to allow the elderly to move themselves. This is more dignifying, allowing them to keep their independence. One example would be an ‘exo-skeleton’ providing movement, fine motor skills and strength. This is a lower cost and it is simpler from a legal perspective – the user maintains responsibility for their actions.

Now, I want to contrast physical infirmity with mental infirmity. Technology for the former is currently very expensive but will come down in cost. But it will still be a substantial cost. Compare this with this unforecast regarding mental care…

In caring for patients with dementia, it is often best to lie to minimise distress. Carers should go along with what is being said, and steering the conversation onto something else. Going over the same conversations will be tedious for the carer. Potentially, a digital assistant could do much of this work (note again: this is trying to increase productivity rather than getting ‘the machines’ to do everything). These assistants (e.g. Alexa, Siri) can quite easily be given a face (just as the film industry can use CGI to map human faces to non-human faces). See below regarding an animated talking head ‘Zoe’:

Consider a psychology-trained dementia carer (we will also call her Zoe) who looks after many dementia patients. Occasionally, she can visit her patients and have face-to-face interaction. But for much of the time she is assisted by many virtual Zoes – one per patient. These virtual Zoes appear as if via videophone and can engage the patients in conversation. As well as providing supportive responses (suitably evasive, as with ELIZA), they can also record the conversations, learn from them and filter relevant information to feed back to real-Zoe for assessment. Real-Zoe monitors conversations and guides the software for many patients. If need be, real-Zoe can visit the patient in person but for the vast proportion of the time, a patient is kept engaged, and always monitored, by a virtual-Zoe. Unlike a human, the Virtual Zoe never tires of the same conversations.

Here is a significant point: Once the software has been developed, the role-out cost is very cheap – not much more than 1 iPad per patient. This is much cheaper than the hardware needed for physical care, mentioned above.

New Process: Platforms

As I have described previously, technological revolutions can involve processes (new ways of doing things) as well as the application of new technology. An example of such a wave of change that is currently underway is the ‘platform economy’. In the late-1990s dotcom boom there was great expectation of companies providing sales and services over the internet (itself the natural consequence of previous revolutions in the electronic technology of computers and communications). But then there was the dotcom crash. The companies that came to dominate afterwards (becoming some of the biggest companies in the world) weren’t just taking sales and services that had previously been done face-to-face and putting them on the internet. A new ‘platform’ way of doing things emerged.

For example, we think of Google as the internet search company (that has now branched out to do other things). But it is really an advertising company. It gets it revenue by providing a free platform whereby internet users can connect with information – but in doing so, Google gathers information about that user which enables it to then provide very focussed advertising to that user (much better than non-internet advertising which is suffering as a result). It is the same with free services like Facebook and Youtube. They are not connecting people to share information from the goodness of their hearts.

But there are other innovative methods that are being employed. One is the ‘freemium’ model where a basic service is provided for free but users can pay extra to get a ‘premium’ service. Examples of this are LinkedIn, Spotify and Skype.

Then there are the so-called ‘peer-to-peer’ services which connect people to other ‘ordinary people’ who provide some service using what they have, as a part-time activity. People can provide ‘virtual internet stores’ on Ebay. People can use their cars to provide Uber taxi services. People can use spare rooms to provide Airbnb ‘bed-and-breakfast’ (or similar) services.

Another phenomenon is providing a service that actually is done from the goodness of people’s hearts. People are willing to donate time and money to provide free products like Linux and LibreOffice and Wikipedia that are substitutes for products like Microsoft Windows, Microsoft Office and Encyclopedia Britannica – and these are products that are expensive (the first two have made Bill Gates the richest man in the world!). Some of these free products are actually superior than the original! (I would nominate Wikipedia as one of the modern Wonders of the World.)

A characteristic of these platforms is the near-zero marginal cost – the cost of setting up the product (website) initially (including the development of software) may be substantial but the cost of adding an extra user (‘customer’) is virtually nothing. For example, the total Facebook storage of 200 Petabytes for 2 billion users gives an average of 1Mbyte per user. You or I can currently buy hard drives at around $30 per terabyte (but Facebook buys disks in bulk!) That equates to 0.003 cents per user! (OK, it’s a bit more complicated than that, but you get the idea.)

Unforecast 3: Coffee Shops

What might a Starbucks outlet of the future look like? Many imagine stereotypical Japanese humanoid robots travelling around delivering coffee. But here is a different vision; a mini-unforecast:

  • The word ‘tablet’ has gained a new meaning since the arrival of computer devices like iPads. The word is of course a diminutive of ‘table’. Touchscreen ‘tables’ (huge iPads on legs) would provide an ‘internet café’ with huge screens that you don’t have to carry around.
  • Beyond normal computer/internet usage, the screens would be used to make your order and pay (just by placing your phone on a particular part of the screen).
  • We are conservative in our built environment. Our bars and restaurants are typically fake imitations of bars and restaurants of yesteryear. A vending machine might be able to make coffees to particular requirements faster and more cost effective than a human but they have no soul! So imagine instead a self-operating Gaggia providing a theatre-like performance of making the coffee: the sounds of the steam and the knocking out spent coffee into the bin as well as the visual, including the specifically-ordered choice of pattern on the top.
  • That just leaves delivering the drinks to the table (customers could help themselves to be quicker), clearing up afterwards, and opening up and shutting up shop (including managing the vacuum-cleaning robots). These tasks will be done most cost-effectively by humans for some time to come. The tasks are less frenetic than those of the human baristas that presently work feverishly away behind the counter.

After automation has taken away significant parts of the job, the job is less skilled but (hopefully) less stressful. Now: when are robots going to be cost-effective at automating those remaining tasks?

We will return to this Starbucks of the future in a short while.

Unforecast 4: University Education

The Flipped Classroom

Lecturers have talked in front of students for centuries:

Lecturing is that mysterious process by means of which the contents of the note-book of the professor are transferred through the instrument of the fountain pen to the note-book of the student without passing through the mind of either.

In an era when lectures can be recorded, it is absurd to employ lecturers to perform. In the Flipped classroom model, students view a recorded lecture and the teachers then support the students in their exercises (frequently left as homework): what is done inside and outside the classroom are reversed. It is after the lecture that students need to be able to ask questions and get help. The lectures teach and the teachers tutor.


It has been possible to broadcast courses to a huge number of students for decades: the Open University in the UK initially broadcast courses on TV in the 1970s. Courses can now be delivered over the internet (of course). Most are what are now called ‘MOOCs’: ‘Massive Open Online Courses’:

  • They are online.
  • This makes them potentially ‘massive’ – huge numbers of students can be accommodated.
  • They may be open, available to all at no cost (example: the Khan Academyon Youtube).
  • They are courses – involving tuition and examination.


  1. Streaming curriculum content to millions is easy.
  2. Having a business model to sustain the courses is more difficult.
  3. But it is the tuition and examining that is the difficult part of on-line courses.

Regarding point 2: One MOOC provider is Coursera. It provides university-level on-line courses. In some cases, these courses are virtually the same as actual undergraduate courses. (Incidentally, one of the co-founders of Coursera was Andrew Ng, a Stanford University professor who is a significant figure in the development of Deep Learning.) They have a Freemium business model. If you pay a modest fee, you can get a certificate to prove (to a potential employer, for example) that you passed the test. But if you don’t want to have proof, the course is free.

And now regarding point 3: The lack of a MOOC solution to tuition and examining means that it has promised much but not delivered – so far. New technology is available but is has been applied to old methods with limited effect. It requires new processes to improve how courses can be run on a massive scale such that they have a dramatic impact on education.

We cannot assume that new technology will not impact ‘safe jobs’. I think that the impact of automation on primary education will be small and that it will noticeably change the way teachers work in secondary schools – automation will not affect their job security. But I believe that the apparent failure of MOOCs so far has made most universities complacent. It is like the false-start of the dotcom boom and subsequent bust which was then followed by the emergence of the FANG (Facebook, Amazon, Netflix, Google) giants which is leading to a long slow decline in so many old economy businesses. This will apply to many universities once innovative new processes for MOOCs are discovered.

Next I turn to ideas about new processes in (predominantly university) education.

Peer to Peer

Examination by multi-choice is simple and is easily automated so a course can satisfy the ‘M’ of the ‘MOOC’. But it has its limitations, particularly dependent on the subject of the course being offered. Examination by essay needs a number of markers proportional to the number of students. This is possible (it is what is done currently, after all) but it is difficult for a single institution to roll out a course ‘massively’. More efficient ways of examining are sought; new processes are desired.

Just as Facebook get its users to gather information for then directing advertising to them, one approach is to get the students to mark students exams! This is ‘peer-to-peer’ marking, otherwise known as ‘peer assessment’.

One example is as follows. After submitting an essay, a student receives 5 anonymous essays to mark, with guidance on the various criteria that should be used, and they send back a score. Students will then get a marker’s grade as well as an essay grade; the closer your scores are to those of others, the better your marker’s grade will be. This would be supplemented by plagiarism-detecting software and random spot checks by professional markers employed by the course provider.

The Examination Game

Andy Clark tells a tale of how, years ago, the philosopher Dan Dennett was talking to an eminent professor of paleontology (who he does not name). The professor complained that his students were cheating at stratigraphy by just copying out diagrams from books. Dennett responded that he should get them to play a computer game. If you want to test their understanding of stratigraphy, you don’t ask the question ‘describe how such-and-such a layer is formed’; you provide them with a game in which various knobs cause various events, such as:

  • Deposition of sediment,
  • Erosion,
  • Intrusion of lava, and
  • Controlled fracture

If the students can play the game by twiddling the knobs in a correct order and with the correct intensity to create the required layers, they have demonstrated that they really do understand the process and can be marked accordingly.

Furthermore, the examiner doesn’t need to spend time marking the results. The game provides the score itself. Obviously, it takes time and effort to create such a game but, once written, there is near-zero marginal cost – it can be rolled out on a massive scale.

Note: games have cropped up again in this talk. Just as games provide a simple controlled environment to test Artificial Intelligence programs, they also provide an automatable controlled environment to test human intelligence. Another controlled environment that lends itself to automated examination is virtual reality – also associated with games.

Starbucks University

MOOCs fall short of the true university experience in not having students interacting face-to-face with each other and with the various services of the university. The MOOC model hasn’t quite been perfected such that it can seriously compete with the traditional bricks-and-mortar universities.

But here’s another ‘un-forecast’ (one that is more outlandish than the previous ones). Imagine that Starbucks buys Coursera (for a huge sum of money). They do that because they recognize that their 27,000 outlets can provide the physical location for students to meet and socialize and receive tuition and pastoral care from experts.

In unforecast #3, I presented a vision of coffee outlets of the future in which the residual job for humans to do comprised of tasks like clearing tables and locking up shop – – performing unskilled, minimum wage type work. But many of the staff across the 27,000 sites of the ‘Starbucks University’ could be upgraded to highly-skilled counsellors providing pastoral care to students and acting as ‘local tutors’. There would also be ‘remote tutors’, present on online subject-specific forums. The remote tutors would be experts in their subject. The local tutors would not be expert in any subject other than how to study through MOOCs. They would teach ‘Learning how to learn’. The local tutors would work with the students to help them find answers themselves. Only rarely would this involve a 3-way spoken interaction between the student, the local tutor and the remote tutor.

For many courses, there would still need to be a residential part of the course, but this would be a small fraction of the course period.

This is not a ‘near-zero marginal cost’ business model that allows rapid expansion leading to domination of the market, but it provides a marginal cost much less than traditional universities:

  • The ratio of remote tutors to students would be much lower than the ratio of lecturers.
  • The ratio of local tutors to students would be much lower than the ratio of assistants.

The economies of scale would mean that early adopters could enrol hundreds of thousands of students per year whilst the majority of remaining universities would fall by the wayside, with some becoming a provider of low-cost accommodation for young people and a provider of venues for residential course modules. Many of these early adopters are prestigious universities. Why pay significant sums of money to a middling traditional university when you can pay less for an online degree from a prestigious university?

Course fees would be split between the course provider (the university) and the course facilitator (Coursera, becoming Starbucks) but would be much lower than present fees. It is much better for a university to move from charging 10,000 students per year to charging 400,000 students at a quarter of the rate.

But course facilitators (Starbucks could be in competition with other coffee chains) may not charge at all!

Starbucks may gain income from its newly-acquired educational services but it could be that it earns nothing directly (making those courses very cheap);

Just as Google and Facebook provide free services to the public as a means of earning revenues in seemingly unrelated business, Starbucks’s provision of free university services could just be a way of selling more cups of coffee! This would be achieved by:

  • Students drinking coffee during the day whilst they study, rather than elsewhere, and
  • Students preferring to drink (discounted) coffee in their leisure time in the evenings making it economic for most Starbucks outlets to stay open late. Other destinations for students would suffer as a result.

The point of this (and other) unforecasts are to emphasize that:

  • The new ways of doing things (processes) that are enabled by the new technology will often be surprising.
  • Roles in supposedly ‘safe’ occupations may change radically; many jobs in ‘vulnerable’ occupations will not disappear anytime soon.
  • This can result in dramatic increases in productivity. Alternatively viewed, it can mean that costs to customers can be dramatically reduced.
  • This can be very bad for many complacent organizations who think that they are generally immune from the new technology.
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The New Technological Revolution

Automation, Education and Work, part 1

There is a proliferation of articles in the media about how the accelerating technology of artificial intelligence and robots will change the world of work radically in the next 30 years. “47% of current jobs are under threat”. “Self-driving vehicles will put millions of truck drivers out of work”. “We are seeing a hollowing out of middle-income jobs.”

Some say this Luddite fear is unwarranted. “Just because we can’t imagine what new jobs will come along doesn’t mean the next generation won’t”. “We just need to educate everyone for the future knowledge economy.”

Others say “This time it’s different”. “We cannot compete with the robots”. “Maybe we need to tax the robots and have Universal Basic Income?”

This is the first of three parts of the talk ‘Automation, Education and Employment’ which will look beyond these articles, at

  1. how technological revolutions happen,
  2. what the new technology actually is, and
  3. how things may turn out differently from what we expect.

In this first part, I look at the first two items on that list.

Technological Revolutions of the Past


The Russian economist Nicolai Kondratiev identified technological waves with a period of about 50 years. This starts with the industrial revolution around 1800 – the classic landmark being James Watt’s improvements to the steam engine around 1781 (examples, names and dates provide some reference points).

The third wave, around 1900, is sometimes called the ‘second industrial revolution’ with many developments of different underlying technologies:

  • the internal combustion engine (Otto 1876 and Diesel 1893),
  • plastics (Baekeland – 1907)
  • improvements to the electric motor (Sprague 1886)
  • the telephone (Bell 1876) and wireless communication (Marconi 1897)

Around 50 years earlier (1850), there were innovations such as steel-making (Bessemer 1856), fertilizer (von Liebig 1840) and rubber (Goodyear 1844).

And around 50 years later (1950), there was the invention of the transistor (Bardeen, Brattain and Schockley 1947) and integrated circuit (Kilby and Noyce 1958) and of the theories of computing (Turing 1936) and information (Shannon 1948).

I note that each wave has launched a fundamentally (truly revolutionary) new technology as well as bringing in innovations building on previous revolutions. Each wave can be associated with an engineering department in a university:

  • 1800: mechanical engineering
  • 1850: chemical engineering
  • 1900: electrical engineering
  • 1950: information engineering, i.e. computer science

The early waves provided physical innovations: human, horse, wind and water power were replaced by the mechanical, chemical and electric power of machines. In contrast, the latest waves are providing cognitive innovations, reacting to events in the world with useful, appropriate and increasingly intelligent responses.

But there is another aspect to these waves: new technologies lead to new ways of doing things – new processes. When a new technology comes along, people typically apply it to their existing world as a better alternative to something more primitive. It typically takes a generation or two to shed the preconceived notion of what the technology is ‘for’ such that people who have grown up with that technology invention being familiar discover new ways of doing things with that technology.

Ford’s innovation of the production line (1908) was helped by the concurrent innovations of the internal combustion engine and electric motor, which made the layout of the factory less dependent on distributing a single common power source around the factory floor. But the production line method of manufacture could have been applied to the steam-engine-powered production of steam-powered cars – it is just that its effect – the mass ownership of cars – would have been far less pronounced. Ford’s factory also built upon previous process innovations such as Marc Brunel’s use of standard components in the Portsmouth Block Mills (1803) and in Isambard Kingdom Brunel’s development of the institution of an engineering business (1843). So there has been the transformation of manufacture over a period of less than 250 years from the ‘cottage industry’ LINK ‘putting out’ system to automated factories (1948, as a consequence of the combined application of electric motors and computers).

The Current Technological Revolution

The Current Technological Revolution is a cognitive one, building on previous ones – the combination of electronic computers (Turing, Kilby and Noyce) and communications (Bell and Shannon) with the landmark development being the internet (reaching the mainstream public around 1995). The dotcom bubble burst after many companies tried to do things using the internet in the same way as done without the internet. Since then, companies like Google and Facebook have come to dominance by applying entirely new business models. More on that later.

And finally, after promising so much for so long, artificial intelligence has finally come of age. For many years, there has been progress along ‘traditional’ computing lines – skilled computer scientists writing programs. First it was to (unashamedly) imitate intelligence (Weizenbaum’s ‘ELIZA’  program, following on from the 1936 ‘Turing Test’ imitation game thought experiment). Then there were landmark moments like IBM’s Deep Blue beating the world chess champion Gary Kasparov (1997) and IBM’s Watson beating the champions-of-champions in the U.S. general knowledge TV quiz show ‘Jeopardy!’ (2011). But in the very early years of computing, it was recognized that the enabling technology (transistors) could be put together based on how the brain is connected rather than the programmed computer. These ‘artificial neural nets’ promised much but delivered little for so long. But then, in 2016, there was the landmark achievement of Deepmind’s AlphaGo beating the world Go champion, Lee Sedol. Go is more strategically complex than Chess but AlphaGo is not an incremental improvement upon Deep Blue. It is a revolutionary development.

To beat Kasparov, IBM had a team of programmers writing algorithms to search for good chess moves and were helped by a chess grandmaster for building up a store of opening moves. Deep Blue’s intelligence was built upon the superior intelligence of its makers. Watson’s intelligence was built upon storing thousands upon thousands of Wikipedia pages. But AlphaGo was just put in an environment that defined the rules of the game and it practiced playing Go over and over again until it was pitted against Sedol and won.

The traditional, programmed approach was intelligence of the artificial kind in the way that an artificial flower is artificial – it is an imitation. But I would argue that there is nothing artificial about the intelligence of ‘artificial neural networks’. They are only artificial in the sense that they are not natural (naturally, biologically evolved).


Since I am not familiar with the game of Go and I suspect that you probably aren’t either, I will illustrate the learning behaviour with the example of another, simpler game – the computer arcade game Breakout.  Google Deepmind trained a machine up to play this game only a year earlier, in 2015.

The network consists of many ‘artificial neurons’, each having a value of its own (e.g. a for neuron ‘A’, for example) and connected to other artificial neurons’ by ‘weights’ (e.g. wab being the weight from neuron A to neuron B), simple numbers that indicates the strength of the connections between neurons.

If neuron A ‘s inputs are from neurons B,C and D, the new value of a, a’, is derived as follows:

x = b.wba+c.wca+d.wda

a’ = f(x)

where f(x) is some ‘activation function’ we do not need to go into here. Basically, there is just adding and multiplying going on here (but with many, many iterations, with many, many neurons, that becomes a huge number of additions and multiplications). During use, all neurons are getting updated all of the time. During training, the weight values just get modified.

For the game, the screen can be divided into about 1000 pixels, each with a number representing a particular colour. These 1000 numbers are the input to the network – analogous to the firing of the retina for the brain. And there are just 2 outputs. The machine just plays the game over and over again. At the end of each game, the score influences the net: higher scores mean ‘what you did is good’ so the weights are modified so that it is more likely to act similarly in future. This is what is called ‘reinforcement learning’.

If we watch what is going on, after perhaps a thousand games, it looks like it has worked out that there is a ball on the screen and the 2 outputs control whether the paddle moves to the left or right. After a few thousand games, it is hitting the ball with some proficiency. After a few more thousand games, it seems to have noticed that bricks on the back wall disappear when they are hit and that the game ends when the ball can break through that wall. There will be a higher score the sooner this is done. After a few more thousand, it is able to play better than any human. Now, this explanation describes behaviour in terms of intentions: ‘the computer has worked out…’. But all that is actually happening is that weights are being modified within the network.

Someone wrote the programming code for the Breakout game in the first place, someone wrote the code for a network (with no specified application and a load of randomly-assigned weights), and someone wrote code to:

  1. start running the game,
  2. control the game from the network’s outputs,
  3. feed it its visual inputs,
  4. tell it its score value at the end of the game, and
  5. tell it to update its weights.

But nobody gave the network any code about the rules of the game. It just worked them out by itself, starting by having its 2 outputs randomly waggling. The only information it was provided was the score – a good score meant that weights between neurons that fired together were ‘strengthened’ (the numbers were increased a bit).

Note: There has been a lot of games mentioned above (and there will be more to come). Games provide a very simple environment for ‘intelligent machines’ to operate in. This allows researchers to concentrate on the machines rather than the environment that the machines are made to interact with and it allows comparison between the machines.

The amount of skilled programming required for an artificial neural network is not large. It is the sheer amount of number crunching across many, many artificial neurons during training that gives rise to its intelligent behaviour.

Below is a Python program to implement, train and use a basic multi-layer neural network.


In this code, the size of the network is determined by the vector num_neurons_in_layer. For example, if we set it to [100, 1000, 1000, 1000, 1] it will have 5 layers, with be 100 neurons in the input layer, 1 neuron in the output and 3 ‘hidden layers’ of 1000 neurons each. If the number of layers is more than 4, the network is considered to be ‘deep’ hence we encounter the terms ‘deep neural nets’ and ‘deep learning’.

The point here is not to examine the code above in any detail (see here for that) but just to show:

  1. how little code is needed for someone to create the neural network itself,
  2. how easy it is to define a large network, and
  3. that there is nothing specific to the application in here.

The ‘magic’ is in the huge, indecipherable set of numbers that make the so-called weights that adjust themselves during learning. The programmer has to create the setup so that the network can learn, at the right pace, in the right way and for the right duration. But the programmer does not need to specify anything about what the network needs to do. Once the learning has been started, the programmer does not need to do anything whilst the network is learning.


Moore’s law gradually increased computer processing power over the years to the point that impressive things could be done with ordinary amounts of hardware (e.g. PC processors and graphics processors). The previous disappointments were because we underestimated just how many artificial neurons (how much number-crunching) were needed to get it to do useful things.

But we are now are the stage where advanced ‘intelligent’ behaviour can be trained into these machines with relatively little effort on the part of humans. And, astoundingly, Moore’s law continues to work. The application of this technology to new applications is rapid. We just need lots of data to train a network in the first place.

Big Data

The internet helps when it comes to having lots of data. For example, Facebook has lots of data associating photos of people with their name, age and gender. We could train a network with this data so that, given a face, it could guess what gender or age it is (and guess very well).


Alternatively, the network could be trained to identify specific individuals from faces.

Note: It would have to a very deep network to be able to do this…


It is this technology that enables machines to read hand-written numerals very well, understand what we say (voice recognition by digital assistants such as Siri and Alexa), identify which tumours are cancerous, doing this better than specialist can…


and detect objects in a street scene that would help self-driving cars navigate their way around.


The New Revolution

So, when I am talking about the new technology that is driving changes to employment and education, I am talking about:

  1. The continuation of existing technology: the application of ‘traditional’ programming techniques to use computers, electric motors and various electronics sensors to automate physical and cognitive tasks as they have been being automated over the past 50 years, in the factory and on-line.
  2. The new technology of deep learning and its application to the automation mentioned above. (Intelligent robots just comprise artificial intelligence plus the technology above)
  3. The new processes of the currently technological wave, namely the ‘platform’ business models of the likes of Google, Amazon and Facebook.
  4. The combination of these new processes with the new technology of deep learning.

(I am not going to speculate about what might come in the next technological wave.)

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Model Housing for the Third Age

And now for something completely different. In a complete departure from neuroscience and philosophy, here’s something on architecture (social housing)…


The Need

The UK housing market is broken. Politicians talk about creating more affordable housing to help first time buyers onto the housing ladder, because of a shortage of housing.

The UK provision for caring for the elderly is broken. Many elderly (from the baby-boomer generation) want to live in the houses they raised their families in, and stay close to their friends and family, but they are in villages or the suburban sprawl, away from easily-accessible services – particularly services needed by the elderly (doctors, nursing and care workers). As their friends and relatives die off and with deteriorating mobility themselves, they become isolated. They have left it too late to move.

The obvious way towards solving these problems is for them to help cancel each other out: the new homes that should be built should be ones targeted towards the ‘over 55s’ (people of the ‘third age’), to give them the flexibility they need as their circumstances change, and affordable access to the services they need. As the baby-boomer generation downsize (probably needing some financial incentive to move or disincentive to stay), many under-occupied family houses would then become available to younger people currently in over-occupied accommodation. The generation below can move up the housing ladder, making existing housing at the bottom more affordable. Every start home built might provide additional accommodation for 2 people. For every small property built for downsizing over 55s, the net increase might be 4 people. And there needs to be a shift of the balance between starter and retirement homes because of the changing demographics.


The Flexibility Concept

The dwelling will be single-storey for convenient wheelchair/disabled access. It is 21st Century ‘two-up/two-down’. It comprises two reception rooms and two bedrooms but these are split into a suite of two 1-bedroom, 1 reception room halves which have in interconnecting passage between them. And each reception room has provision for kitchen area. Unlike its 19th Century counterpart, it has inside toilets – two in fact. Each half has a ‘wet-room’ providing the toilet, a washbasin and a shower area. Whilst, in principle, a free-standing bath could be placed in the wet-room, it is intended to allow the disabled to get washed more easily. This room is accessible selectively from either the corridor or a bedroom.

It will have an ‘over 55’ restrictive covenant and be part of a larger housing trust development in which there are care home/nursing home facilities.

The use of the dwelling can change as personal circumstances change:

  • It provides a 2-bed accommodation with kitchen, dining room and lounge. In principle, the wetrooms could provide 2 toilets during the day and 2 en-suite toilets at night. In practice, the occupants might keep one permanently as an en-suite and the other as a general toilet.
  • The lounge can have a small kitchenette area and the connecting corridor between dining room and lounge can be locked from both sides, creating two 1-bedroom properties. This option means that, for short durations, the occupants can ‘retreat’ into one half of the property, for friends/relatives to stay in the other.
  • It would also give them the flexibility to let out the ‘other half’ of the property as Airbnb short-term accommodation for example, particularly to friend/relatives of those in the care home or other dwellings.
  • Probably on the death of one of the occupants, that split could become ‘permanent’, with the other half rented out on long-term lets.
  • Home care would be readily available as circumstances dictate because of the proximity of the care home and the elderly in other homes within the development. (Nurses and carers would not need travelling time.)
  • The care home could rent ‘other halfs’, for extra accommodation – an accommodation service somewhere between ‘care home’ and ‘home care’.


The Eco Concept

Even though the property is small, it will still have a relatively large footprint because it is single-storey dwelling. Land is expensive. It is difficult to get permission to build on green land. Contrast this with the ability to turn green fields over to solar farms.

Aim: to build properties with as high a proportion of land area given to solar panels as possible. We are not putting panels on top of houses – we are putting houses under a solar farm! Because it is only single storey, it will have low visual impact. Panels are typically mounted at least 50cm off the ground. We are only ‘raising’ them by about 2m.  It may be possible to have these houses within an actual solar farm, placed, for example, in a lower corner of the field, sheltered by mature trees, such that there is very low visual impact.

The panels would be face due South. The North-facing rooves would be ‘green’. This would reduce the visual impact but would also provide very good roof insulation. Given that the South-facing rooves are fully covered, skylights will be needed for getting (indirect) light into the house.

Then there are the walls. For best insulation, as many walls should be shared. ‘Back-to-back’ houses would be very efficient but sharing 3 walls with neighbours can be a problem with noise as well as fire. The solution is to have large voids between the dwellings, perhaps 1.5m wide. Noise and fire insulation would be comparable with detached houses. The ‘shared’ walls (it is the voids that are shared) are not exposed to the elements but they are not visually exposed either, which will reduce their cost. This can compensate for the cost of the superior thermal insulation of the one genuinely-exposed wall.

The solution actually proposed is ‘front’-to-front’ terracing. The back wall provides access to the garden/yard of the property. The front walls face onto a shared corridor with fire exits at both ends, like a hotel corridor (but wider). An entrance lobby might be at one end, possibly connecting to a care home/nursing home (details are not relevant here).

The voids could possibly be used for local storage of the energy generated from the PV panels in batteries. With the solar panels and excellent thermal characteristics, this housing should be able to meet the requirements of various environmental initiatives such as the Passivhaus, ZEB (Zero-energy buildings) and ‘Energy Plus houses’ concepts. But it is not actually a requirement that any of those designations are formally achieved.


The Drawings

The picture below shows 2 rows (back-to-back) of 6 properties.


The proportion of area covered by solar panels is maximized by having panels in the gardens. These panels are hinged to provide more space in the garden if desired. The 4th property from the left in the front row has its yard solar panels down. It also has its yard divided into 2, as would be normal where properties have one half let out.

The South-facing side of the roof is covered in solar panels. The North-facing side is a green (living) roof, with rooflights.


Each property comprises two identical halves. The space can be utilized as a 2-bedroom house:


Or as two halves:


Each wet-room is accessible both from the corridor and a bedroom:


The South-facing solar panels cover the vast majority of possible surface area:


The North-facing green roof helps the development to fit into a green-field site:


Finally, the regular cross-section off the buildings lends itself to pre-fabrication. Modular sections can be built in a precisely-controlled factory environment and transported to the building site for rapid construction. This could include pre-fabricating the wet room within its wall section. Pre-fabrication leads to higher quality as well as lower cost.


In all the pictures above are only intended to show the concept. Dimensions are not relevant; walls have zero thickness.

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Friston on Freud

An ambitious, speculative 2010 paper co-authored by Karl Friston attempts to tie together Sigmund Freud’s psychoanalytic descriptions of the ‘id’ and the ‘ego’ with modern neurobiological accounts of self-organized hierarchical cortical systems – such as Friston’s own ‘variational free energy’ theory:

Carhart-Harris, R. L. & Friston, K. J. (2010). The default-mode, ego-functions and free-energy: a neurobiological account of Freudian ideas. Brain133: 1265–1283. DOI: 10.1093/brain/awq01

A PDF of the paper is available on Friston’s UCL pages here but it is not searchable and there is supplementary material hidden away in a zip file. Here, I just present the information of the whole paper including the supplementary material in a single web page.

Some commentators on this paper are:

The default-mode, ego-functions and free-energy: a neurobiological account of Freudian ideas

R. L. Carhart-Harris1 and K. J. Friston2

1 Neuropsychopharmacology Unit, Imperial College London, Hammersmith Campus, Du Cane Road, London, UK

2 The Wellcome Trust Centre for Neuroimaging, 12 Queen Square, London, UK

Correspondence to: R. L. Carhart-Harris,

Neuropsychopharmacology Unit,

Imperial College London,

Hammersmith Campus,

Du Cane Road,





Received August 16, 2009. Revised and Accepted December 23, 2009.

The Author(s) 2010. Published by Oxford University Press on behalf of Brain.

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (, which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. Brain Advance Access published February 28, 2010


This article explores the notion that Freudian constructs may have neurobiological substrates. Specifically, we propose that Freud’s descriptions of the primary and secondary processes are consistent with self-organized activity in hierarchical cortical systems and that his descriptions of the ego are consistent with the functions of the default-mode and its reciprocal exchanges with subordinate brain systems. This neurobiological account rests on a view of the brain as a hierarchical inference or Helmholtz machine. In this view, large-scale intrinsic networks occupy supra-ordinate levels of hierarchical brain systems that try to optimize their representation of the sensorium. This optimization has been formulated as minimizing a free-energy; a process that is formally similar to the treatment of energy in Freudian formulations. We substantiate this synthesis by showing that Freud’s descriptions of the primary process are consistent with the phenomenology and neurophysiology of rapid eye movement sleep, the early and acute psychotic state, the aura of temporal lobe epilepsy and hallucinogenic drug states.


  • Freud
  • the ego
  • default-mode
  • prediction
  • free-energy


  • BOLD = blood oxygen level dependent;
  • DMN = default-mode network;
  • fMRI = functional magnetic resonance imaging;
  • REM = rapid eye movement


In this synthesis we explore the notion that Freudian constructs may have real neurobiological substrates and could be usefully revisited in the context of modern neuroscience. It is worth noting that Freud had a formal training in neuroanatomy and was influenced by people like Helmholtz, who laid many of the foundations for theoretical neurobiology. Advances in empirical and theoretical neuroscience now allow us to recast some central Freudian ideas in a mechanistic and biologically informed fashion. Specifically, we note that the psychoanalytic distinction between the primary and secondary processes (as functions of the id and ego respectively) fit comfortably with modern notions of functional brain architecture, at both a computational and neuro-physiological level. Although this may seem a rather abstract and ambitious synthesis, there is in fact an enormous amount of empirical evidence from neuropsychology, neuroimaging and psychopharmacology to support it.

In what follows we attempt to demonstrate consistencies between key Freudian ideas and recent perspectives on global brain function that have emerged in imaging and theoretical neuroscience. The intention is to demonstrate and develop the construct validity of the Freudian concepts. This should allow Freudian concepts to be operationalized and measured empirically and could enable a dialogue between psychoanalysts and neuro-biologists. This may have implications for psychiatry to the extent that mechanistic theories of psychopathology appeal to either neurobiological or psychoanalytical constructs. We start by summarizing the key elements of the three areas that we want to relate to each other; namely the central Freudian constructs, the Helmholtzian or Bayesian brain framework and empirical findings from neuroimaging on the global organization of brain activity.

The primary and secondary process

Freud came to a realization that there are two fundamentally different modes of cognition (the primary and secondary process) through a study of ‘altered’ or ‘non-ordinary’ states of consciousness (e.g. Q115, Q333 and Q462 in Supplementary material). He recognized in certain non-ordinary states (e.g. dreaming and psychosis) a mode of cognition that is characterized by a primitive, animistic style of thinking. Freud conjectured that the exchange of neuronal energy is relatively ‘free’ in this mode and he named this the ‘primary process’. Simultaneously, Freud recognized in non-ordinary states the loss of certain functions, which are normally present in waking cognition. He ascribed these functions to a central organization (the ego) which works to minimize the mind’s free-energy. Freud named this function the ‘secondary process’ and defined its aim as one of converting ‘free energy’ into ‘bound energy’ (for a more thorough discussion of these central concepts of Freudian theory see the supporting quotes in the online Supplementary material, cited in Table 1): We seem to recognize that nervous or psychical energy occurs in two forms, one freely mobile and another, by comparison, bound; we speak of [activations] and [hyperactivations] of psychical material, and even venture to suppose a [hyperactivation] brings about a kind of synthesis of different processes — a synthesis in the course of which free energy is transformed into bound energy We hold firmly to the view that the distinction between the [primary] and the [secondary] state lies in dynamic relations of this kind, which would explain how it is that, whether spontaneously or with our assistance, the one can be changed into the other We have found that processes in the unconscious or in the id obey different laws from those in the ego. We name these laws in their totality the primary process, in contrast to the secondary process which governs the course of events in the ego. (Q461, Freud, 1940)

Table 1

List of quotations pertaining to the characteristics of the secondary process (and the ego) and primary process thinking (and the id). Q numbers refer to quotes given in the Supplementary material, below.

The ego and the secondary process: Relevant quotations from Freud

  1. Default energy store or reservoir, which possesses the property of being spontaneously or tonically active. Q5, Q15, Q109, Q154, Q162, Q209, Q273, Q298, Q300, Q301, Q314, Q320, Q321, Q416, Q438, Q454
  2. Receives and ‘contains’ or ‘represses’ endogenous excitation. Q1, Q15, Q46, Q80, Q132, Q152, Q154, Q183, Q205, Q209, Q212, Q219, Q283, Q283, Q287, Q328, Q358, Q363, Q391, Q392, Q427, Q427, Q429, Q437, Q448, Q475
  3. Minimizes free-energy. Q2, Q8, Q18, Q70, Q199, Q200, Q283, Q285, Q307, Q314, Q321, Q366, Q373, Q410, Q461, Q483
  4. Integrates or binds the primary process and its representational system (the id) into a broader, more cohesive, composite organization (the ego). Q15, Q29, Q45, Q46, Q154, Q209, Q218, Q231, Q233, Q234, Q237, Q300, Q302, Q308, Q314, Q315, Q334, Q339, Q351, Q358, Q360, Q383, Q384, Q385, Q391, Q397, Q402, Q413, Q429, Q447, Q461, Q483
  5. Specific ontogenetic development. Q47, Q113, Q174, Q273, Q300, Q301, Q358, Q414, Q440, Q459, Q486
  6. Supports reality-testing and perceptual processing. Q15, Q19, Q23, Q39, Q51, Q153, Q234, Q258, Q259, Q310, Q350, Q356, Q363, Q373, Q375, Q380, Q392, Q427, Q428, Q429, Q448, Q482, Q485
  7. Supports conscious awareness, cognition and directed attention. Q10, Q21, Q27, Q39, Q40, Q153, Q154, Q204, Q234, Q238, Q249, Q254, Q334, Q372, Q380, Q427
  8. Possesses internally and externally-focused components, which are inversely related (anti-correlated). Q6, Q39, Q162, Q173, Q204, Q243, Q273, Q289, Q300, Q301, Q320, Q329, Q363, Q438, Q448, Q454, Q484
  9. Excessive-engagement of internally-focused component and impoverished engagement of externally-focused network during pathological withdrawal; e.g. in depression and schizophrenia. Q144, Q147, Q158, Q161, Q168, Q169, Q170, Q172, Q244, Q252, Q253, Q263, Q265, Q266, Q267, Q277, Q288, Q292, Q293, Q297, Q301, Q329, Q330, Q368,
  10. Failure of systems to minimize free-energy (suppress endogenous excitation) results in disturbed affect, cognition and perception; as seen in non-ordinary states such as dreaming and psychosis. Q23, Q35, Q58, Q115, Q134, Q135, Q147, Q231, Q261, Q262, Q333, Q365, Q383, Q455, Q462, Q466, Q469, Q475, Q476, Q482, Q485

The id and primary process thinking: Relevant quotations from Freud:

  1. Characteristics of the system unconscious/the id and primary process thinking: i.e. a primitive, ‘magical’ or animisitic style of thinking, characterized neurophysiologically by ‘free’ movement of energy. One can think of primary process thinking in evolutionary terms as a ‘protoconsciousness’. Q58, Q63, Q90, Q92, Q97, Q115, Q135, Q151, Q160, Q171, Q198, Q201, Q203, Q209, Q211, Q216, Q217, Q218, Q228, Q229, Q230, Q231, Q233, Q237, Q241, Q242, Q247, Q249, Q254, Q257, Q261, Q270, Q279, Q280, Q282, Q299, Q305, Q311, Q315, Q335, Q359, Q388, Q389, Q396, Q397, Q423, Q424, Q425, Q426, Q437, Q440, Q442, Q443, Q446, Q453, Q461, Q465, Q467, Q468, Q470, Q471, Q472, Q474, Q477, Q479, Q480, Q482, Q490, Q491

The quotations can be found in Supplementary material.

Free-energy and the Bayesian brain

In terms of theoretical and computational neuroscience, we will focus on Helmholtz’s suggestion that the brain is an inference machine (Helmholtz, 1866; Dayan et al., 1995); this idea is now a fundamental premise in neurobiology (Gregory, 1968). Key examples of this include the Bayesian brain (Knill and Pouget, 2004), predictive-coding (Rao and Ballard, 1998) and the free-energy principle (Friston, 2009). This framework assumes that the brain uses internal hierarchical models to predict its sensory input and suggests that neuronal activity (and synaptic connections) try to minimize the ensuing prediction-error or (Helmholtz) free-energy. This free-energy is a measure of surprise and is essentially the amount of prediction-error. It is an information theory quantity that, mathematically, plays the same role as free-energy in statistical thermodynamics. Free-energy is not an abstract concept; it can be quantified easily and is used routinely in modelling empirical data (Friston et al., 2007) and in neuronal simulations of perception and action (Friston et al., 2009). The notion of a hierarchy is central here because it allows the brain to construct its own top-down prior expectations about sensory samples from the world. This resolves one of the key challenges facing the brain and also allows it to resolve ambiguities when inferring and representing the causes of exteroceptive and interoceptive sensations. Crucially, the hierarchical form of internal models (and associated neuroanatomy) (Felleman and Van Essen, 1991) entails a progression in the complexity of representations, as one proceeds up the hierarchy from thalamic nuclei and primary sensory cortex to association and paralimbic cortex (e.g. from sensations, through perceptions to concepts). This progression is reflected in the temporal extent of what is represented; with higher levels representing extended sequences of events that best account for the stream of sensory information represented in lower levels (see Kiebel et al., 2008 for a full discussion and simulations).

The hierarchical architecture may also accommodate the distinction between the Freudian primary and secondary processes, where the secondary process provides top-down predictions to reduce free-energy associated with the primary process (cf. converting free energy into bound energy). Under this mapping between Freudian and Helmholtzian models, one can link the energy associated with the primary process and the free-energy of Bayesian formulations. In both accounts, higher cortical areas are trying to organize activity in lower-levels through suppression of their free-energy.

Intrinsic brain networks and the default mode

Analyses of spontaneous Auctuations in the blood oxygen level dependent (BOLD) signal of functional magnetic resonance imaging (fMRI) during unconstrained ‘resting’ states (typically lying quietly with eyes closed or fixating on a cross) have identified a number of large-scale intrinsic networks (Beckmann et al., 2005; Damoiseaux et al., 2006). Of particular interest here is the so called ‘default-mode network’ (DMN), a network of regions that show high metabolic activity and blood flow at rest but which deactivate during goal-directed cognition (Raichle, 2001). Recent work has confirmed that the major nodes of the DMN are functionally and structurally connected (van den Heuvel et al., 2008; Greicius et al., 2009) and that this connectivity develops through ontogeny (Fair et al., 2008; Kelly et al., 2009). Another feature of the DMN is the inverse relationship of its neuronal activity with that of another large-scale intrinsic network; the ‘attention system’ (Fox et al., 2005; Fransson, 2005; Corbetta and Shulman, 2002). In this article, we pursue the idea that these intrinsic networks correspond to the high-levels of an inferential hierarchy, which function to suppress the free-energy of lower levels (i.e. suppress prediction errors with top-down predictions). We associate this optimization process with the secondary process. Furthermore, we associate failures of top-down control with non-ordinary states of consciousness, such as early and acute psychosis, the temporal-lobe aura, dreaming and hallucinogenic drug states. In what follows, we organize the evidence that speaks to the integration of neurobiological and psychoanalytic ideas and conclude with a defence of its value and potential utility. This article comprises three sections: in the first, we review evidence that the development and functioning of the DMN is consistent with ego-functions and the secondary process. We focus specifically on the DMN’s containment of endogenous excitation and its suppression of systems engaged by exogenous stimuli. In the second, we review evidence that a loss of top-down control over limbic activity in hierarchically lower systems is equivalent to a loss of the ego’s control over the primary process. In the final section, we discuss the clinical relevance of these ideas.

Large-scale intrinsic networks, the secondary process and ego

In this section, we introduce the idea that Freud’s descriptions of the development and functioning of the ego resonate with the development and functioning of the DMN and its reciprocal exchanges with subordinate brain systems. Freud’s first useful account of the ego was given in his posthumously published Project for a Scientific Psychology (Freud, 1895). Inspired by the recent introduction of ‘neurone theory’ by Cajal and Waldeyer-Harz, Freud hypothesized three functionally-distinct classes of neurone: the ‘w neurones’, which receive endogenous input and make up the ego; the ‘neurones’, which are sensitive to exogenous input; and the ‘x neurones’, which signal qualitative information. Although this neuronal classification system was abandoned by Freud soon after its conception, the ideas that inspired it remained a source of influence throughout his work. Several of Freud’s most important ideas were introduced and/or developed in the Project, including the notion that the ego is an organization that receives and contains/represses bottom-up endogenous excitation (Table 1, row 2; Q1, Q15, Q46 and Q429). The secondary process, or ‘secondary process cognition’, is the mode of cognition of the ego; put simply, it is the mode of normal waking consciousness of adult humans (e.g. Q317). Freud described the secondary process as ‘inhibited’ and ‘bound’; in contradistinction to the primary process which is ‘free’ and ‘motile’ (Freud, 1895, 1900). The concept of ‘bound’ energy was attributed by Freud to ideas first expressed by Breuer in their Studies on Hysteria (Breuer and Freud, 1895). Breuer conjectured the existence of a system of tonically active neurons, forming a ‘reservoir of nervous tension’ (e.g. Q45, Q154 and Q233). It is significant that the primary and secondary processes owe their inception to observations of non-ordinary states of consciousness (e.g. row 10, Table 1; Q23, Q35, Q115, Q333 and Q462). We shall see later that compelling evidence for the existence of two distinct modes of cognition can be found in studies of non-ordinary states. In what follows, we review the functional anatomy of the default-mode and related networks and then consider these networks from a theoretical perspective.

Functional anatomy of the default-mode

The notion of the DMN originated in a paper by Marcus Raichle reviewing a pattern of blood flow, glucose metabolism and oxygen consumption in the resting-state, which consistently decreases during goal-directed cognition (Raichle, 2001); in other words, a high-level distributed system whose activity is reciprocally related to the activity in cortical areas subserving task or stimulus-bound processing. Raichle proposed that this pattern reflects a default mode of brain function and a functionally relevant physiological baseline (Raichle, 2001). Subsequent work has associated activity in the network identified by Raichle and others (Greicius et al., 2003; Beckmann et al., 2005; Damoiseaux et al., 2006; Fransson and Marrelec, 2008; Wu et al., 2009) with phenomena such as self-referential processing, autobiographical recollection, mind-wandering and theory-of-mind (Gusnard et al., 2001; Vincent et al., 2006; Mason et al., 2007; Buckner et al., 2008; see also Q332). Regions specifically implicated in the DMN include the medial prefrontal cortex, the posterior cingulate cortex, the inferior parietal lobule, the lateral and inferior temporal cortex and the medial temporal lobes (Buckner et al., 2008; Fransson and Marrelec, 2008). Analyses of resting-state functional connectivity and diffusion tensor imaging have showed that the major nodes of the DMN are strongly interconnected (Greicius et al., 2003, 2009; Van den Heuvel et al., 2009) and that this connectivity matures through development (Fair et al., 2008; Kelly et al., 2009). Functional connectivity in the DMN is relatively weak in the elderly (Andrews-Hanna et al., 2007; Damoiseaux et al., 2008) and in patients with attention deficit disorder (Castellanos et al., 2008) and impulse control disorders (Church et al., 2009). Interestingly, medial prefrontal cortex-posterior cingulate cortex connectivity is entirely absent in infants (Fransson et al., 2007). These findings imply that the DMN develops through ontogeny, in a manner that parallels the emergence of ego-functions (Table 1, row 5). Model and data-driven analyses of resting-state functional connectivity, diffusion tensor imaging analyses of structural connectivity and anatomical work in primates suggest that the medial temporal lobes are connected to the medial prefrontal cortex and posterior cingulate cortex nodes of the DMN (Catani et al., 2003; Vincent et al., 2006; Buckner et al., 2008; Fransson and Marrelec, 2008; Kahn et al., 2008; Saleem et al., 2008; van den Heuvel et al., 2008; Robinson et al., 2009). This is important because the medial temporal lobes contain key structures (e.g. the hippocampal formation, the amygdala, parahippocampal gyrus and entorhinal cortex) that play a role in mnemonic and hedonic or emotional processing. The evidence suggests that medial prefrontal cortex-medial temporal lobe functional and structural connectivity increases through ontogeny (Eluvathingal et al., 2007; Kelly et al., 2009) with a notable increase at puberty (Benes et al., 1989). A recent study found reduced medial pre-frontal cortex-amygdala functional connectivity in patients with schizophrenia and an inverse correlation between connectivity and aggression in these patients (Hoptman et al., 2009). Preclinical work indicates that emotional extinction takes place via glutamatergic projections from the medial prefrontal cortex terminating on inhibitory interneurons in the medial temporal lobes (Rosenkranz and Grace, 2002; Rosenkranz et al., 2003) and a recent analysis of effective connectivity implied that activation of the rostral anterior cingulate drives inhibition of the amygdala in response to fearful faces (Stein et al., 2007). There is a huge amount of clinical and preclinical evidence supporting the limbic-suppressive function of the medial prefrontal cortex (Hariri et al., 2000; Milad and Quirk, 2002; Rosenkranz and Grace 2002; Phillips et al., 2003; Phelps et al., 2004; Etkin et al., 2006; Milad et al., 2006). Functional neuroimaging studies have correlated primitive thought and emotion with decreased activity in the medial prefrontal cortex and increased activity in the medial temporal lobes (Pietrini et al., 2000; Dougherty et al., 2004), while suppression of these behaviours correlated with medial prefrontal cortex activations (Pietrini et al., 2000; Beauregard et al., 2001; Dougherty et al., 2004). The recollection of distressing memories and emotions in patients with post-traumatic stress disorder has also been found to correlate with medial prefrontal cortex deactivations and medial temporal lobe activations (Bremner et al., 1999; Shin et al., 2004, 2006; Hopper et al., 2007) and the blockade of these memories also correlated with medial prefrontal cortex activations (Lanius et al., 2002; Reinders et al., 2003, 2006). Damage to the ventro-medial prefrontal cortex has long been associated with impaired impulse control (Grafmen et al., 1996; Anderson et al., 1999; Davidson et al., 2000; Kaplan-Solms and Solms, 2001; Solms and Turnbull, 2002). The medial prefrontal cortex sends dense projections to the ventral striatum (Ferry et al., 2000) and mid-brain (Carr and Sesack, 2000). The ventral striatum displays functional connectivity with the midbrain, medial temporal lobes and higher-level nodes of the DMN (Postuma and Dagher, 2006; Di Martino et al., 2008; Gutman et al., 2009) and the midbrain and ventral striatum signal prediction-error and motivational-salience (Robbins and Everitt, 1996; Berridge and Robinson, 1998; Schultz, 2002; Kapur, 2005). In summary, the DMN comprises high-level cortical nodes such as the medial prefrontal cortex that exchange neuronal signals with subcortical systems and other association and polymodal cortex, especially the systems responsible for emotional learning and memory. Much of the evidence suggests that activation of the DMN suppresses activity in lower systems. We now consider these aspects of functional anatomy in the light of hierarchical inference and the secondary process.

Figure 1


The DMN (yellow/orange) and attention system (blue): resting state functional connectivity of three seed regions: the dorsal medial prefrontal cortex, ventral medial prefrontal cortex and hippocampal formation (medial temporal lobes). Positive correlations (yellow–orange) with all seeds were evident in the posterior cingulate (PCC), posterior inferior parietal lobule (pIPL) and medial prefrontal cortex (mPFC). Regions negatively correlated with these seeds constitute the attention system and include the superior parietal lobule (SPL), intraparietal sulcus (IPS), the motion-sensitive middle temporal area (MT+), the frontal eye fields (FEF) the dorsal anterior cingulate (dACC), the dorsolateral prefrontal cortex (DLPFC), the ventral premotor cortex and the frontal operculum. Image reproduced from Buckner et al. (2008), with permission.

Theoretical formulations of the default mode

Freud argued that the ego modulates both endogenous and exogenous excitation. Empirically, this can be seen in early and acute psychosis, the aura of temporal lobe epilepsy and hallucinogenic states, where affective (e.g. fear), mnemonic (e.g. moments of deja vu or vivid recollection), perceptual (e.g. hallucinations) and cognitive (e.g. confused or muddled thinking) processing is perturbed (Bleuler, 1911; Epstein and Ervin, 1956; Cohen, 1964; Vollenweider et al., 1997) (Table 1, row 10; e.g. Q462). He further hypothesized that the ontogenetic/phylogenetic evolution of healthy, adult waking cognition depends on the formation of an equilibrium between the pressing forces of the primary process (entailed by the id) and the counter forces of the secondary process (entailed by the ego) (e.g. Q116). This description is remarkably consistent with contemporary models of cognition based on hierarchical Bayesian inference and Helmholtzian free-energy; where backward connections from higher cortical areas work to minimize the free-energy of lower areas (Mumford, 1992; Rao and Ballard, 1999; Friston, 2003; Kiebel et al., 2009). Anatomically speaking, forward connections originate in supra-granular layers and terminate in layer four spiny stellate cells. They project from lower to higher-levels; e.g. from thalamic nuclei to primary sensory cortex or from secondary sensory cortex to tertiary sensory areas. Backward connections are more abundant and diffuse than forward connections and their effects are primarily modulatory. Backward connections originate in deep pyramidal cells (infragranular layers) of the cortex and target infra and supragranular layers of lower cortical areas. Based on Bayesian and Helmholtzian principles it has been proposed that forward connections convey prediction-errors that optimize representations in higher levels. These representations are then used to form predictions that are conveyed by backward connections to lower levels. These predictions suppress or cancel prediction-errors (free-energy) until they can be minimized no further (Friston, 2003, 2005). In this way, the brain optimizes its representation of the world by suppressing prediction-errors with reciprocal message passing between hierarchical levels to minimize free-energy. This suppression simply involves countering excitatory presynaptic inputs (from representational units to neurons encoding prediction-error) with top-down presynaptic inputs, mediated by inhibitory interneurons. When the representations at any level can be explained by top-down predictions from the level above, prediction-error is minimized and the representations are internally consistent over levels. The aim of this process is to optimize parsimonious explanations for what caused sensory input (Friston, 2003) and establish sensory predictions to guide action and behaviour (Friston et al., 2009). Crucially, this empirically-informed scheme (Sandell and Schiller, 1982; Girard and Bullier, 1989; Hupeu et al., 1998; Kleinschmidt et al., 1998; Murray et al., 2002; Lachaux et al., 2005; Chen et al., 2008) recapitulates Freud’s 19th century conception and in particular his principle of constancy: [We] have taken the view that the principle which governs all mental processes is a special case of Fechner’s ‘‘tendency towards stability’’, and have accordingly attributed to the mental apparatus the purpose of reducing to nothing, or at least of keeping as low as possible, the sums of excitation which flow in upon it. (Freud, 1924; Q366) It is significant that Freud cited as his inspiration for these ideas, Gustav Fechner, the founder of psychophysics and a contemporary of Helmholtz (e.g. Q307, Q353, Q366, Q379): the process of minimizing ‘the sums of excitation’ is exactly the same as minimizing the sum of squared prediction-error or free-energy in Helmholtzian schemes. This rests on the assumption that the brain explicitly encodes prediction-error with neuronal activity (excitation) that is suppressed or explained by backward (top-down) afferents. As mentioned above, Freud argued that the ego modulates and suppresses both exogenous and endogenous signals (Table 1, rows 2 and 6). In neurobiological terms, exogenous signals correspond to interoceptive and exteroceptive signals from thalamic and unimodal sensory areas that convey sensory signals (prediction-errors) to polymodal and medial temporal lobe structures. Endogenous signals could be equated with subsequent bottom-up prediction errors (excitation) arising in limbic and paralimbic systems, which are passed up to high-level polymodal cortical areas that comprise the nodes of the default-mode. Clearly, the principles that attend hierarchical inference under Helmholtzian schemes are generic and may apply to all hierarchically deployed brain systems. However, we will focus on the DMN; specifically, on medial prefrontal suppression of limbic and paralimbic activity, and associate this with the suppression of endogenous activity by the ego. We now consider how the ego modulates excitation evoked by stimuli from the external world.

Hierarchical brain systems

As discussed in the introduction, BOLD signal oscillations in the DMN are characterized by their inverse relation to those of another major intrinsic network, referred to as the attention system (Corbetta and Shulman, 2002; Fox et al., 2005; Fransson, 2005). As well as showing a spontaneous inverse relationship with the DMN, the attention system is activated during externally-directed cognition and deactivated during internally-directed cognition, whereas the opposite is true of the DMN (Buckner et al., 2008); implying a ‘give-and-take’ relationship (Raichle, 2009). Regions implicated in the attention system include the dorsolateral prefrontal cortex, the dorsal anterior cingulate cortex, the frontal eye fields, the extrastriate cortex (e.g. V5) the superior parietal lobule, the intraparietal sulcus and the ventral premotor cortex (Buckner et al., 2008). These regions are active during target detection, attention to spatial detail and hand-eye coordination (Corbetta and Shulman, 2002; Shulman, 2003). Moreover, many of these nodes have been associated with top-down control of primary sensory input (Friston and But chel, 2000; Lachaux et al., 2005). High-level association cortices not only receive feedforward signals from sensory regions but also anticipate and reciprocate these inputs with backward connections conferring context-specificity and higher-level constraints (i.e. predictions) (Rao and Ballard, 1999; Friston, 2003, 2005; Angelucci and Bressloff, 2006). Recent work has suggested that what we have referred to as the ‘attention system’ is in fact not a unified system. Based on independent component analyses of resting state BOLD activity, Seeley et al. (2007) have shown that the system described by Fox et al. (2005) and Fransson (2005) can be differentiated into a ‘salience system’ which includes the dorsal anterior cingulate cortex, frontoinsular cortices, amygdala and ventral mid-brain; and a more dorsal and lateral cortical system (the ‘dorsal attention system’) which includes the dorsolateral prefrontal cortex, frontal eye fields, dorsal medial prefrontal cortex, intraparietal sulcus and superior parietal lobule. BOLD signal oscillations in both systems exhibit an inverse relationship with those in the posterior cingulate cortex of the DMN (Greicius et al., 2003) but the systems do not appear to be well integrated with each other. This differentiation has also been suggested by others (He et al., 2007; Dosenbach et al., 2008; Sridharan et al., 2008; Vincent et al., 2008). The picture that emerges is of a hierarchy of brain systems with the DMN at the top and the salience and dorsal attention systems at intermediate levels, above thalamic and unimodal sensory cortex. Under a Helmholtzian model, each system is trying to suppress the free-energy of its subordinates, through a process of optimizing predictions to reduce prediction-errors. This rests on recurrent message-passing between these systems that leads to self-organized activation patterns with a characteristic reciprocity or ‘give-and-take’ among levels. In this view, activation of the attention system may facilitate the suppression of exogenous excitation (Q258). Similarly, the DMN furnishes top-down control of the attentional and salience systems by explaining and thereby suppressing their activity. We next address the physiological basis of message-passing or interactions among brain regions that mediate this self-organized suppression.

Spontaneous BOLD oscillations and neuronal activity

Until recently, there had been some uncertainty about whether spontaneous BOLD-signal oscillations are generated by neuronal activity or non-neuronal physiological processes (Wise et al., 2004; Birn et al., 2006). Recent work has shown that spontaneous BOLD oscillations most probably have a neuronal origin (He et al., 2008; Nir et al., 2008; Shmuel and Leopold, 2008). Simultaneous fMRI and intracranial recordings in monkeys (Shmuel and Leopold, 2008) and humans (Nir et al., 2007) have identified spontaneous neuronal fluctuations that correlate with spontaneous BOLD fluctuations (Shmuel and Leopold, 2008). The neuronal fluctuations, which are coherent across the hemispheres, were evident in multi-unit firing rates and local field potential gamma power. Stimulus evoked BOLD activations have also been shown to correlate positively with gamma power (Niessing et al., 2005). Gamma has been associated with attention, feature-binding and expectancy (Singer and Gray, 1995; Herrmann, 2000; Engel et al., 2001). This suggests that BOLD fluctuations reflect cortical coherence associated with gamma and secondary process cognition, particularly since the gamma frequency, recorded in higher-level cortical areas, has recently been shown to suppress lower frequencies in lower-level cortical areas (Chen et al., 2009). This leads us to predict that the fluctuations in gamma power evident in the large-scale intrinsic networks index the ongoing minimization of free-energy in subordinate levels of the hierarchy (Engel et al., 2001; Raichle, 2007) and could provide an empirical measure of the secondary process. Generally speaking, oscillatory processes are ubiquitous in the brain and serve to couple remote neuronal populations. High frequency gamma has often been implicated in perceptual synthesis and binding (e.g. Singer, 2009); while theta rhythms have been most studied in the hippocampal system, where they are associated with (spatial) memory and exploration (e.g. Lisman and Redish, 2009). Crucially, theta and gamma are themselves coupled (e.g. Sirota et al., 2008), where slower theta oscillations may provide a temporal frame of reference for faster computations mediated at gamma frequencies. We will return to the oscillations and frequency-specific coupling in the brain in the next section. So far we have discussed the importance of reciprocal or anti-correlated activity in the DMN and networks for goal-directed cognition. However, it should be noted that spontaneous fluctuations in the DMN continue during active cognition, just as spontaneous fluctuations in the dorsal attention system continue during rest (Hampson et al., 2002; Beckmann et al., 2005; Damoiseaux et al., 2006; Fox et al., 2007). This tonicity presumably primes structures to infer exogenous inputs (Fox et al., 2007; Raichle, 2007) and supports a background level of predictive coding (Hampson et al., 2002). Furthermore, spontaneous fluctuations in the BOLD signal, which can be as large in amplitude as evoked BOLD responses (Fox et al., 2007), have been shown to reflect variations in behaviour (Boly et al., 2007; Fox et al., 2007). Much of the brain’s vast energy budget is reserved for spontaneous neuronal activity (Fox and Raichle, 2007; Raichle, 2007). We speculate that spontaneous activity in the DMN reflects the constant containment of spontaneous endogenous activityO commensurate with Freud’s concept of repression (Q209), while spontaneous activity in the dorsal attention system indexes the continual monitoring and suppression of exogenous stimuli. This conjecture appeals to the Helmholtzian view of the brain as an inference engine that continually generates predictions and hypotheses that, when freed from the present (Kiebel et al., 2009), necessarily entails the past and future. In addition to the functional importance of spontaneous neuronal activity in intrinsic networks, the give-and-take between the default system and task-positive systems appears to be vital for active cognition and conscious awareness (Pomarol-Clotet et al., 2008; He and Raichle, 2009; Whitfield-Gabrieli et al., 2009). Functional connectivity within the DMN has been shown to increase through ontogeny (Fair et al., 2008; Kelly et al., 2009), decrease in ageing (Andrews-Hanna et al., 2007; Damoiseaux et al., 2008) and to be underdeveloped in patients with impaired impulse control (Church et al., 2009). These findings imply that functional connectivity in the DMN (Hampson et al., 2006) and the dorsal attention system (Seeley et al., 2007) provides an index of cognitive aptitude but not necessarily active cognition (Larson-Prior et al., 2009). Ineffective deactivation of the DMN has been associated with cognitive error in healthy subjects (Li et al., 2007; Eichele et al. 2008) and negative symptoms in schizophrenia (Pomarol-Clotet et al., 2008; Whitfield-Gabrieli et al., 2009) and depression (Grimm et al., 2009; Sheline et al., 2009). Functional connectivity in the DMN is not significantly altered in sleep, sedation or coma (Boly et al., 2008; Larson-Prior et al., 2009) but the give-and-take between the DMN and its anti-correlated networks is (He and Raichle, 2009) (see Q238).

Figure 2


Resting state functional connectivity in three cortical networks: (i) dorsal attention system (DAS, blue) using voxels in the middle temporal area and superior parietal lobule as regions of interest; (ii) the salience system (light green) using voxels in the anterior PFC and anterior inferior parietal lobule as regions of interest; and (iii) the default mode network (orange) using the hippocampal formation and posterior inferior parietal lobule as regions of interest. Overlap between the networks is shown in dark green (salience system and DMN) and red (dorsal attention systems and salience system). Image used with permission from Justin Vincent and Randy Buckner.

Summary and synthesis

In this section, the secondary process was considered in relation to large-scale intrinsic networks working to predict and suppress excitation (Helmholtz free-energy) in subordinate systems. The concept of the secondary process entailed by ego-functions was associated with the suppressive effect of the DMN on its subcortical nodes and anti-correlated networks. Functional connectivity between limbic (e.g. the hippocampus and amygdala) structures and major nodes of the DMN during rest (Buckner et al., 2008; Di Martino et al., 2008) supports the notion that the systems enacting ego-functions have evolved to receive and control endogenous excitation that underlies mnemonic and hedonic processing. In the next section, we focus on the primary process and specifically how it is manifest in non-ordinary states of consciousness.

The phenomenology of primary process thinking

In this section we describe the phenomenology of non-ordinary states of consciousness that have been associated with primary process thinking. The primary process is not generally regarded as a serious topic of science but the phenomenology of certain non-ordinary states compel us to consider its importance. Psychoanalysis owes its origins to observations of non-ordinary states (Table 1, row 10; e.g. Q23, Q35, Q115, Q333; Q462). An early observation that has remained at the core of the Freudian model is that there exists in the mind an archaic mode of cognition, which under normal waking conditions is effectively suppressed (Q315). Freud saw this ‘primary’ mode as belonging to an ontogenetically and phylogenetically primitive system, which he referred to initially as ‘the unconscious’ (Breuer and Freud, 1895), later as ‘the system unconscious’, ‘system Ucs’ or just ‘Ucs’ (Freud, 1900, 1915 b) and eventually as ‘the it’ (Freud, 1923) (note: Freud’s original term for ‘the id’ was ‘das es’ and should really have been translated ‘the it’, just as his original term for ‘the ego’, ‘das Ich’, should have been translated ‘the I’; for simplicity however, we will use the familiar terms ‘id’ and ‘ego’). Thus, the term ‘the id’ was introduced relatively late by Freud (Freud, 1923) as a new name for ‘the unconscious’ in its systematic sense (i.e. ‘the system unconscious’ or ‘system Ucs’) (Freud, 1900, 1915 b). Freud wrote relatively less about the id than the system unconscious but the two are essentially synonymous (see Q422, Q423, Q458 and Q461). Freud’s decision to rename the system unconscious ‘the id’ was motivated by his acknowledgement that aspects of the ego are also unconscious (in the descriptive sense) and processes in the id can become conscious. The introduction of the id was useful in this respect as it resolved ambiguities relating to the descriptive meaning of ‘unconscious’. Referred to as ‘the id’, the unconscious could be understood more explicitly as a system subserving a specific mode of cognition (e.g. Q461). The characteristics of primary process thinking are clearest when contrasted against those of the secondary process: just as the characteristics of the primary process only become manifest in certain non-ordinary states, the characteristics of the secondary process only really become evident when they are lost. For example, Freud considered timelessness to be a major characteristic of the id and time perception to be a function of the ego (e.g. Q424). The notion of timelessness is difficult to comprehend from the vantage of normal waking consciousness but becomes clearer if we consider the phenomenology of states such as the temporal lobe aura: ‘Time seems endless’ (Epstein and Ervin, 1956); acute psychosis: ‘Time slowed down, much more experience could be crowded into a brief time span’ (Bowers, 1965) and the hallucinogenic drug state: ‘[Under the influence of drugs such as LSD, one has] the feeling that so much was ‘‘seen’’ that ‘‘hours’’ or ‘‘days’’ or ‘‘aeons’’ must have passed’ (Masters and Houston, 2000). Recent work involving the serotoninergic hallucinogen, psilocybin, has shown that hallucinogen-induced impairments in temporal perception are dose-dependent (Wackermann et al., 2008). Furthermore, recent formulations of the free-energy principle suggest that there is a systematic increase in temporal coherence in higher-level structures (Kiebel et al., 2009). Thus, impaired temporal perception is a property of primary process thinking that has the potential to be measured psychophysically; thus bringing previously intangible phenomena into the scientific realm. Four other qualities of primary process thinking that can be assessed empirically include the following.

  1. (i) Sensations of fear or dread, e.g. in the aura of temporal lobe epilepsy: ‘I feel afraid, as if something awful might happen’ (Williams, 1956); early psychosis: ‘Suddenly Fear, agonizing, boundless, Fear, overcame me, not the usual uneasiness of unreality, but real fear, such as one knows at the approach of danger, of calamity’ (Sechehaye, 1951); the hallucinogenic drug state: ‘I found myself all at once on the brink of panic’ (Huxley, 1954); and dreaming: ‘Fear is the most frequently occurring dream emotion’ (Bulkeley, 2009).
  2. (ii) Perceptual distortions/visual hallucinations, e.g. in the aura of temporal lobe epilepsy: ‘The surroundings feel strange and unfamiliar’ (Hansen and Brodtkorb, 2003); early psychosis: ‘It wasn’t really unreal; it was just strange, funny, different’ (Cutting and Dunne, 1989); and the hallucinogenic drug state: ‘The room and furniture were distorted, strange and terrifying’ (LSD, Cohen, 1964).
  3. (iii) Deja vu, recollective or reliving phenomena, e.g. in the aura of the temporal lobe epilepsy: ‘I went back to all that occurred in my childhood’ (Hughlings-Jackson, 1879); early psychosis: ‘My whole world seemed to cave in — I kept thinking about my birthplace and my past’ (Cutting and Dunne, 1989); and the hallucinogenic drug state: ‘I started to cry uncontrollably and nothing could have stopped it — it was like a dam giving way. At first I didn’t know what I was weeping about, but soon became aware that I was reliving childhood experiences of which I had scarcely any conscious knowledge. Until today I had remembered only fragments, but now the entire sequence reeled off as from a microfilm that was securely stored within my head’ (LSD, Cohen, 1964).
  4. (iv) Disturbance to the sense-of-self, e.g. in the aura of temporal lobe epilepsy: ‘I felt that I disappeared’ (Johanson et al., 2008); early psychosis: ‘When I look at somebody my own personality is in danger. I am undergoing a transformation and myself is beginning to disappear’ (Chapman, 1966); and the hallucinogenic drug state: ‘I felt the relaxing of the self boundaries’ (LSD, Cohen, 1964). Other characteristics of primary process thinking include a fear of losing control of ones mind, a general sense of the peculiarity of things, euphoria, grandiosity, paranoia and suspiciousness, thought-disturbances, bizarre thought-content and an increased interest in mystical, magical or animistic notions. All these phenomena could easily be assessed using subjective rating scales as a global measure of ego-disturbance or primary process thinking. However, an association between the primary process and dreaming, acute psychosis, temporal lobe aura and hallucinogenic states can be motivated at a purely phenomenological level. Crucially, all these states have been compared with each other previously; e.g. psychosis and dreaming (Freud, 1900; Jung, 1907; Bleuler, 1911); psychosis and the temporal lobe aura (Slater and Beard, 1963; Bear, 1979; Ferguson and Rayport, 2006); psychosis and the hallucinogenic drug state (Behringer, 1927; Bowers and Freedman, 1966; Gouzoulis et al., 1994); dreaming and the temporal lobe aura (Rodin et al., 1955; Penfield and Perot, 1963; Mahl et al., 1964); dreaming and the hallucinogenic drug state (Grof, 1975; Fischman, 1983; Callaway, 1988); and the temporal lobe aura and the hallucinogenic drug state (Bercel et al., 1956; Schwarz et al., 1965; Balestrieri, 1967). It is also worth noting that dreaming (Freud, 1900), psychosis (Freud, 1900; Bleuler, 1911), the temporal lobe aura (Kubie, 1952; Robin et al., 1955; Delgado et al., 1956; Epstein and Ervin, 1956; Ostow, 1957; Mahl et al., 1964; Horowtiz et al., 1968) and the hallucinogenic drug state (Busch and Johnson, 1950; Sandison et al., 1954; Cattell, 1957; Martin, 1957; Eisner, 1959; Cohen, 1964; Abramson, 1967; Horowitz et al., 1968; Grof, 1975) have all been described as states conducive to the emergence of primary process thinking. In the remainder of this section we will review evidence that these states, which clearly display a related phenomenology, also possess a related neurophysiology.

Neurophysiology of the primary process

In this section, we show that brain states associated with primary process thinking have common neurophysiological substrates. Intracranial electroencephalography (EEG) recordings in medial temporal structures, the superior temporal gyrus and the visual association cortex, after high-frequency stimulation of the perirhinal cortex, reveals bursts of synchronous high-amplitude theta activity spreading from the medial temporal lobes to the visual association cortices during the hallucinatory revival of past experiences (Barbeau et al., 2005). This activity is consistent with Freud’s speculations about the processes underlying dreaming and related states (e.g. Q97 and Q98). Similar activity has been recorded in the medial temporal lobes of other epileptic patients during states of hallucinosis and recollection (Rodin et al., 1955; Heath, 1961; Stevens et al., 1969) and increased theta power has been recorded over the medial temporal lobes during recollection using magnetoencephalography (Guderian and Dut zel, 2005). In the 1950s and early 1960s, activity was recorded in cortical and subcortical structures in a large number of patients experiencing acute psychotic episodes (Heath, 1954; Lesse et al., 1955; Sem-Jacobsen et al., 1956; Heath and Mickle, 1960; Sherwood, 1962; Heath and Walker, 1985). Subcortical contacts revealed conspicuous activities, which were generally not seen in the cortex or at the scalp (Sem-Jacobsen et al., 1956; Heath and Mickle, 1960). In actively psychotic patients, spiking and bursts of high-amplitude synchronous activity (of variable frequency but often theta) were recorded in the septum (which until the mid-1970s included the nucleus accumbens) (Heath, 1954; Stevens, 1999) amygdala and hippocampus (Sem-Jacobsen et al., 1956; Heath and Mickle, 1960; Sherwood, 1962). This activity was specific to these regions, was most pronounced when the psychosis was most florid and was absent when the symptoms remitted (Heath and Mickle, 1960). Intracranial recordings in subjects administered the hallucinogenic drugs LSD and mescaline revealed spiking and bursts of high-amplitude activity in the medial temporal lobes similar to that recorded in the acutely psychotic patients (Schwarz et al., 1956; Sem-Jacobsen et al., 1956; Monroe et al., 1957; Heath and Mickle, 1960; Chapman et al., 1962). LSD and related drugs were used extensively in the 1950s and 60s as adjuncts to psychoanalytic psychotherapy (Abramson, 1967; Grinspoon and Bakalar, 1979). Spontaneous recollections of a similar nature to those associated with the temporal lobe aura (e.g. Penfield and Perot, 1963; Barbeau et al., 2005) have been reported after ingestion of LSD and psilocybin (e.g. Sandison et al., 1954; Grof, 1975; Vollenweider et al., 1997). High-amplitude bursts of low-frequency/theta activity have also been recorded in the human hippocampus in rapid eye movement (REM) sleep (Brazier, 1968; Freemon and Walter, 1970; Giaquinto, 1973; Moiseeva and Aleksanyan, 1976; Mann et al., 1997; Y et al., 1997; Bou dizs et al., 2001; Cantero et al., 2003) and LSD given to humans immediately prior to (Toyoda, 1964; Muzio et al., 1966) or during sleep (Torda, 1968) has been shown to promote REM sleep and dreaming. These studies provide converging evidence that a specific mode of cognition (primary process thinking), rests on brain states, which possess a characteristic neurophysiology. There are also some interesting examples of medial temporal activities being influenced by psychiatric interview (Heath, 1954, 1964; Lesse et al., 1955). Sporadic bursts of high-amplitude synchronous activity recorded intracranially in the medial temporal lobes (Heath, 1954, 1964; Lesse et al., 1955) were detected as personal memories, with strong emotional content, were touched on. The activity desynchronized if the patient attended to his environment (Lesse et al., 1955) or carried out a mathematical problem (Heath, 1954, 1964). The abnormal limbic activity recorded in the temporal lobe aura, acute psychosis, the hallucinogenic drug state and REM sleep is often seen in the theta range (Sem-Jacobsen et al., 1955; Heath et al., 1955–56; Schwarz et al., 1956; Sem-Jacobsen et al., 1956; Monroe et al., 1957; Heath and Mickle, 1960; Chapman et al., 1962; Sherwood, 1962; Cantero et al., 2003; Barbeau et al., 2005), although bursts of high-amplitude fast activity were also seen (e.g. Lesse et al., 1955; Heath et al., 1955-56). Hippocampal theta in animals is reliably associated with locomotion, orienting and REM sleep (Kahana et al., 2001) and also long-term potentiation (Hot lscher et al., 1997). Hippocampal theta depends on inputs from the septal nuclei, a major theta generator (Petsche et al., 1962; Winson 1978) and another site from which the abnormal activity was recorded in non-ordinary states in humans (e.g. Heath, 1954; Sherwood, 1962). As well as providing conditions for encoding new experiences, hippocampal theta facilitates the retrieval of past experiences (Hasselmo et al., 2002 Barbeau et al., 2005). Scalp recordings of increased theta power associated with goal-directed cognition (Burgess and Gruzelier, 2000; Krause et al., 2000; Onton et al., 2005) are unlikely to relate to the high-amplitude bursts seen in the septum and medial temporal lobes during the non-ordinary states of consciousness described above (Gevins et al., 1997; Kahana et al., 2001; Buzsaki 2002; Raghavachari et al., 2006). The cortex is capable of generating its own theta (Silva et al., 1991; Raghavachari et al., 2006) and intracranial work in humans has provided more evidence for low-amplitude, high-frequency oscillations in the hippocampus during attentiveness than for theta (Heath, 1954, 1964; Lesse et al., 1955; Halgren et al., 1978; Arnolds et al., 1980; Huh et al., 1990; Meador et al., 1991; Caplan et al., 2001; Axmacher et al., 2007). Moreover, in the non-ordinary states, activity recorded from the scalp and in the cortex is generally low-amplitude, high-frequency and desynchronous (Heath and Mickle, 1960; Chapman et al., 1962; Rodin et al., 1966; Cantero et al., 2003); such activity is highly characteristic of REM sleep (Jouvet, 1965; Maquet et al., 1996; Braun et al., 1998; Cantero et al., 2003; Wehrle et al., 2007) and other cortical ‘up’ states (Steriade et al., 2001) such as those induced by serotoninergic hallucinogens (Lambe and Aghajanian, 2006). Based on empirical findings (e.g. Can) ive et al., 1996; Jeanmonod et al., 1996, 2003; Llinas et al., 1998, 1999) it has been proposed that bursts of limbic theta, recorded in the cortex as increased gamma, can index the positive symptoms of various neurological and psychiatric disorders (Llinas et al., 1999; Jeanmonod et al., 2003; Llinas and Steriade, 2006). Under normal conditions, cortical gamma readily suppresses low-frequency oscillations (Chen et al., 2009). This function is analogous to the secondary process, but in pathological states and dreaming, limbic activity is more anarchic (e.g. Oertel et al., 2007; Wehrle et al., 2007) and the cortex must work harder to contain it (Llinas et al., 1999; Jeanmonod et al., 2003; Llinas and Steriade, 2006). Recent intracranial EEG work in humans, using subdural electrodes recorded theta phase-modulation of high-frequency (80–150Hz) gamma power (Canolty et al., 2006). Theta modulation of gamma power was evident at rest but also during behavioural tasks. Theta-gamma coupling was highest at the trough of the theta phase. Moreover, electrodes showing the highest mean theta power also showed the strongest theta-gamma coupling. These findings imply that theta modulates coupling between theta and gamma and a number of researchers have suggested that theta may promote long-range coupling in cortical networks (e.g. von Stein and Sarnthein, 2000; Buzsaki, 2006).

Summary and synthesis

Integrating these findings, we propose that high-amplitude low-frequency (e.g. theta) discharges in limbic and paralimbic regions index the free-energy of the Helmholtzian scheme and mediate the primary process of the Freudian scheme. In waking cognition, low-frequency limbic oscillations couple to (i.e. entrain) gamma in the cortex (Canolty et al., 2006; Llinau s and Steriade, 2006) enabling the activity of the cortex to explain and thereby contain the activity of the limbic regions (Engel et al., 2001; Friston, 2003; Chen et al., 2009). In non-ordinary states, this function may be perturbed (e.g. in the case of hallucinogenic drugs, through actions at modulatory post-synaptic receptors) (Aghajanian and Marek, 1997), compromising the hierarchical organization and suppressive capacity of the intrinsic networks. To investigate these phenomena further, neuroimaging measures of functional and effective connectivity could be employed to assess whether e.g. phasic events in REM sleep or the hallucinogenic drug state correlate with an increased limbic input to higher-level association cortices. It might transpire that in these states, limbic discharges become capable of traversing systems, which they are unable to do under normal conditions. For example, it might be possible to observe limbic discharges influencing activity in visual association areas (see Barbeau et al., 2005). One might expect limbic activity to be suppressed by higher-level regions of the DMN in normal waking cognition but not in non-ordinary states. This might explain the difference between the experience of day-dreaming in the resting-state (Mason et al., 2007, Q284 and Q332) and hallucinosis in non-ordinary states (Q97), where limbic activity is released from top-down control. The mechanisms of this release have been discussed previously in terms of perceptual inference and synaptic gain (Friston, 2005b; Stephan et al., 2009), where the major determinant of synaptic gain is neuronal synchronization.


In this article we have explored the notion that Freud’s descriptions of the secondary process are consistent with the functional anatomy of large-scale intrinsic networks. We have proposed that intrinsic networks self-organize into hierarchical frameworks, in order to suppress the free-energy of their subordinate levels. This was associated with the function of the secondary process. We hypothesized that spontaneous fluctuations in neuronal activity in cortical nodes of the DMN function to suppress or contain otherwise anarchic and unconstrained endogenous activity in limbic and paralimbic systems, while fluctuations in subordinate networks anti-correlated with the DMN predict and counter prediction errors induced by exogenous sensory input in sensory and visceral systems. Given the nature of this synthesis, different readers will find merit in different aspects of it. For example, some readers may see value in relating inferential coding to intrinsic networks and regard this as a potentially useful perspective on functional anatomy. Others may take the formal similarity between Freudian formulations and functionalist interpretations of neuronal processes as evidence for their construct validity. For example, the remarkable overlap between Freud’s theories and modern neurobiology may engage clinicians and academics who are more familiar with (and receptive to) Freud’s work (Table 2). Developing these points of contact may help anchor Freudian concepts to measurable biological phenomena and inform psychoanalytic thinking. As has been argued previously (Kandel, 1999; Solms, 2009), this process may be important for psychoanalysis. Furthermore, given the enduring, albeit marginal, influence of psychoanalysis in psychiatry, it may benefit psychiatry if psychoanalysis is properly grounded in neuroscience. This is the agenda of the Neuro-Psychoanalysis movement ( and should assist the process of separating premises that have construct validity from those which do not. Freud’s writings contain many useful heuristics for exploring global brain function, especially in non-ordinary states of consciousness. Indeed, the Freudian model owes its origins to inferences based on unconstrained states, whereas the cognitive-behavioural approach is uncertain in this domain (Morcom and Fletcher, 2007). Science usually analyses phenomena extrospectively but in the mind-sciences especially, certain phenomena demand that we look both inwards and outwards – even if introspection entails some compromise and a confrontation with our ‘it’. Freud’s theories were conceived through a study of non-ordinary states, his schooling in neurology and a readiness to introspect. If they were built on false inference and loose philosophy, it is unlikely they would have endured in the way that they have. For those opposed to Freud, who would rather see his constructs dissolved into pure phenomenology and neurobiology, we put up little resistance (e.g. Q176). Phenomenology and neuro-biology can stand alone. The Freudian model adds a framework for an integrated understanding of psychopathological phenomena. Once the full-character of non-ordinary states and cognition are understood, this framework may dissolve naturally. The synthesis attempted in this article is intended to facilitate a more comprehensive understanding of psychological and neurobiological phenomena; addressing topics which have hitherto been considered incompatible with the cognitive paradigm (e.g. Morcom and Fletcher, 2007). The Freudian model should not impede hypothesis testing but rather facilitate it by emphasizing the importance of studying the phenomenology, neurophysiology and neurodynamics of different modes or states of cognition; and by indicating where we might look for anomalies. For example, altered functional connectivity between limbic and cortical nodes of the DMN may predict symptoms of ego-disturbance or primary process thinking. Identifying the neurobiological signature of ego-disturbance or primary process thinking may provide new insights into the pathogenesis of schizophrenia, given that related symptoms are prevalent in the prodromal phase (Maller and Husby, 2000; Parnas and Handset, 2003; Hat fner and Maurer, 2006). Another symptom cluster, which might benefit from a Freudian treatment, is the withdrawal seen in depression and schizophrenia. The association between ego–libido and object–libido and the give-and-take between the DMN and its anti-correlated networks may be especially relevant here: All that we know about [libido] relates to the ego, in which at first the whole available quota of libido is stored up. We call this state absolute, primary narcissism. It lasts till the ego begins to invest the ideas of objects with libido, to transform narcissistic libido [ego–libido] into object–libido. Throughout the whole of life the ego remains the great reservoir from which libidinal investments are sent out to objects and into which they are also once more withdrawn. (Freud, 1940; Q454) The notion of displacing energy from a default store to networks concerned with scrutinizing the external world is consistent with the functional relationship of the DMN to its anti-correlated networks, where e.g. activity is displaced from the DMN to the dorsal attention system during goal-directed cognition (Raichle et al., 2001): We see also, broadly speaking, an antithesis between ego–libido and object–libido. The more of one is employed, the more the other becomes depleted. (Freud, 1914; Q173) It is interesting that Freud’s notion of a finite ‘reservoir’ of energy and the reciprocal patterns of activation between the DMN and subordinate networks both fit comfortably with hierarchical minimization of free-energy. This minimization entails recurrent message-passing between hierarchical brain systems that try to suppress the free-energy at all levels (this scheme is also called predictive coding; e.g. Jehee and Ballard, 2009). The ensuing dynamics mean that increased neuronal activity at one level suppresses neural activity encoding prediction-error in another, leading to reciprocal patterns of activation and deactivation; see Murray et al. (2002) for a nice empirical example of this in the visual system and Friston and Stephan (2005) for a simulation in the auditory system. In brief, the ‘reservoir’ of free-energy is constantly primed by surprising or unaccountable exchanges with the sensorium and is distributed throughout the hierarchy in an attempt to minimize its expression at any one level. Recent work has shown reduced task-evoked suppressions of DMN activity in schizophrenia (Pomarol-Clotet et al., 2008; Whitfield-Gabrieli et al., 2009) the severity of which correlated positively with connectivity in the DMN (Whitfield-Gabrieli et al., 2009). These findings support the observation that there is a reduced engagement with the external world in schizophrenia (see Table 1, row 9 and especially Q168 and Q170). In this article we have proposed that the brain’s functional anatomy is organized hierarchically to ensure that free-energy is minimized in the most efficient way. Organized in this manner, the brain explains internal and external events and effectively discriminates between them. However, assuming that the development and maintenance of this organization is use-dependent, it will be jeopardized if the individual withdrawals from the external world. If the brain’s hierarchical organization begins to breakdown, there may be an ensuing confusion over, among other things, what are internal and external sensations. This may be especially relevant during puberty, when the ego is forced to negotiate new demands from internal and external sources and through this, develop an adult ego. According to our model, the development of an adult ego (a properly functional DMN) is necessary to contain internal excitations and coordinate engagements with the external world. If this is not achieved, systems normally inhibited by the DMN (e.g. the salience system) may slip from its control. In the ensuing chaos, the patient may develop delusions as a compromise strategy for containing the increase in free-energy. Thus, from the free-energy perspective, withdrawal, psychomotor poverty and delusional thinking may be last resorts for someone who finds everything surprizing and unpredictable. See Fletcher and Frith (2009) and Corlett et al. (2009) for a free-energy (predictive coding) treatment of false inference in schizophrenia. As in schizophrenia, Freud recognized that a retreat from the external world is also characteristic of depression. In depression however, emphasis was laid on a loss of an intense object-love. Freud argued that the patient reacts to this loss by targeting the aggression felt towards the lost object back upon his/her own ego: There is no difficulty in reconstructing [the] process of [melancholia]. An object-choice, an attachment of the libido to a particular person, had at one time existed; then, owing to a real slight or disappointment coming from this loved person, the object-relationship was shattered But the free libido was not displaced on to another object; it was withdrawn into the ego Thus the shadow of the object fell upon the ego and the latter could henceforth be judged by a special agency, as though it were the forsaken object One or two things may be directly inferred with regards to the preconditions and effects of a process such as this. On the one hand, a strong fixation to the loved object must have been present; on the other hand, in contradiction to this, the object-[investment] must have had little power of resistance This contradiction seems to imply that the object-choice had been effected on a narcissistic basis, so that the object-[investment], when obstacles [came] in its way, [could] regress to narcissism. (Freud, 1917b, Q267) As in schizophrenia, recent work has shown a reduced task-induced suppression of DMN activity in depression (Grimm et al., 2009; Sheline et al., 2009) and these reductions correlated positively with depression severity and ratings of hopelessness (Grimm et al., 2009). Reduced blood flow and activation in the dorsolateral prefrontal cortex and hyper-perfusion, metabolism and activity in limbic and medial prefrontal regions are also reliably associated with depression (e.g. Mayberg et al., 2005, 2007; Drevets et al., 2008). These findings support the notion of a withdrawal from the external world and a pathological self-focus in depression, consistent with the Freudian account (Table 1, row 9).

Table 2

Some points of contact between Freud’s account of the mind and empirical findings in neurobiology

  • The overlapping phenomenology of REM sleep, early and acute psychosis, the temporal lobe aura and the hallucinogenic drug state.
  • All these states have been independently compared with each other previously and described independently as conducive to primary process thinking.
  • The neurophysiology of these non-ordinary states is remarkably consistent both empirically and with Freud’s descriptions of the ‘free-flowing’ energy of the primary process.
  • LSD given immediately prior to or during sleep promotes REM sleep.
  • The overlap between Freud’s descriptions of the give-and-take relationship between ego–libido and object–libido and the give-and-take relationship between the DMN and its anti-correlated networks.
  • The concordance between Freud’s descriptions of the secondary process working to minimize free-energy and the free-energy account of the hierarchical organization of intrinsic networks working to minimize prediction errors.
  • The integrated, compound nature of the DMN and Freud’s descriptions of the integrated, compound nature of the ego.
  • The development of functional connectivity between the nodes of the DMN during ontogeny, a process that parallels the emergence of ego-functions.
  • Freud’s account of the ego as a recipient and product of regular endogenous activity concerned with drive, memory and affect and the functional and structural connectivity of the DMN’s cortical nodes with limbic structures concerned with drive, memory and affect.
  • Freud’s description of the ego as a tonic reservoir of activity and the high resting-state metabolism of the DMN.
  • Freud’s account of the ego as the seat of the sense-of-self and studies showing increased activity in the DMN during self-referential processing and a failure to deactivate the DMN in pathology characterized by withdrawal.


The first section of this article reviewed evidence that the development and functioning of the DMN and its functional relationship with its anti-correlated networks is consistent with that of the ego. In the second we described the phenomenology of primary process thinking, reviewed evidence that it can be observed in certain non-ordinary states and cited studies indicating that these states share a common neurophysiology. In the final section we sought to justify the synthesis and show how reference to the Freudian model might be used to understand clinically relevant phenomena in neurobiological terms. This article does not address the efficacy of psychoanalysis as a treatment (see Fonagy, 2003 for a relevant review and Q478). Our focus is on the validity of Freudian constructs in relation to global phenomena and related theories that have recently emerged in systems neuroscience. Finally, this synthesis was compelled by the links between psychopathology and the neurophysiology of certain non-ordinary states of consciousness, and between the functional organization of intrinsic brain networks and the secondary process as described by Freud. The synthesis is empirically-led, as are the methods we recommend for testing and applying it. The neurobiological phenomena addressed in this synthesis are central topics in contemporary neuroscience and the Freudian concepts are principal components of his model, where these components can be traced to his schooling in neurology and the influence of people like Meynert, Helmholtz, Fechner, Hering, Herbart, Charcot and Hughlings-Jackson.


We would like to thank our reviewers for very helpful guidance in presenting and extending these ideas.


KJF was funded by the Wellcome Trust. RCH is supported by the Beckley Foundation and has recently received a research grant from the Neuropsychoanalysis Association.


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Supplementary Material


Relevant writings from the Complete Psychological Works of Sigmund Freud

The quotations cited below are considered to be of general relevance and interest to the central manuscript.

Standard Edition, Volume 1. A Project for a Scientific Psychology. 1895.

  • The nervous system receives stimuli from the somatic element itself – endogenous stimuli – which equally have to be discharged. These… give rise to the major needs, hunger, respiration and sexuality. From these the organism cannot withdraw as it does from external stimuli [Q1, Freud, 1895, p. 297a].
  • The nervous system must put up with maintaining a store of [energy] sufficient to meet the demand for a specific action. Nevertheless, the manner in which it does this shows that the same trend persists, modified into an endeavour at least to keep the [energy] as low as possible and to guard against any increases of it – that is, to keep it constant. [Q2, Freud, 1895, p. 297b]
  • Thus there are permeable neurones (offering no resistance and retaining nothing), which serve for perception, and impermeable ones (loaded with resistance, and holding back [energy], which are the vehicles of memory and so probably psychical processes in general. [Q3, Freud, 1895, p. 300a]
  • We can then say: Memory is represented by the facilitations existing between the ψ neurones. [Q4, Freud, 1895, p. 300b]
  • “Here we are almost involuntarily reminded of the endeavour of the nervous system, maintained through every modification, to avoid being burdened by [energy] or to keep the burden as small as possible. Under the compulsion of the exigencies of life, the nervous system was obliged to lay up a store of [energy]. [Q5, Freud, 1895, p. 301]
  • “The system φ would be the group of neurones which the external stimuli reach, the system ψ would contain the neurones which receive the endogenous excitations. [Q6, Freud, 1895, p. 303a]
  • The system φ, which is turned towards the external world… [Q7, Freud, 1895, p. 304]
  • We discover, in fact, that the φ neurones do not terminate at the periphery freely… but in cellular structures which receive the exogenous stimulus in their stead. These ‘nerve-ending apparatuses’, in the most general sense, might well have it as their purpose not to allow exogenous [energy] to make an undiminished effect upon φ but to damp them down. [Q8, Freud, 1895, p. 306]
  • It would be possible to follow a Darwinian line of thought and to appeal to the fact of impermeable neurones being indispensable and to their surviving as a consequence. [Q9, Freud, 1895, p. 303b]
  • In that case, however, a place has to be found for the content of consciousness in our quantitative ψ processes. Consciousness gives us what are called qualities – sensations which are different in a great multiplicity of ways and whose difference is distinguished according to its relations with the external world. Within this difference there are series, similarities and so on, but there are in fact no quantities in it. It may be asked how qualities originate and where qualities originate. These are questions which call for the most careful examination and which can only be treated roughly here.
  • Where do qualities originate? No in the external world. For out there, according to the view of our natural science, to which psychology too must be subjected here, there are only masses in motion and nothing else. In the φ system perhaps? That tallies with the fact that the qualities are linked with perception, but it is contradicted by everything that rightly argues in favour of the seat of consciousness being in the upper storeys of the nervous system. In the ψ system then. Against his, however, there is weighty objection. During perception the φ and ψ systems are in operation together [one engaging while the other disengages]; but there is one psychical process which is no doubt performed exclusively in ψ – reproducing or remembering – and this, speaking generally, is without quality. Remembering beings about de norma nothing that has the peculiar character of perceptual quality. Thus we summon up courage to assume that there is a third system of neurones – ω perhaps [we might call it] – which is excited along with perception, but not along with reproduction, and whose states of excitation give rise to the various qualities – are, that is to say, conscious sensations. [Q10, Freud, 1895, p. 309a]
  • The ω neurones behave like organs of perception, and in them we could find no place for a memory.” [Q11, Freud, 1895, p. 309b]
  • The ω neurones are incapable of receiving [energy] but instead appropriate the period of the excitation and that this state of theirs of being affected by period while they are being filled the minimum of [energy] is the fundamental basis of consciousness. [Q12, Freud, 1895, p. 310]
  • The qualitative characteristics of the stimuli now proceeds unhindered through φ by way of ψ to ω. [Q13, Freud, 1895, p. 314]
  • Now there is a basic law of association by simultaneity, which operates in the case of pure ψ activity, of reproductive remembering, and which is the foundation of all links between the ψ neurones. We find that consciousness – that is, the quantitative activation of a ψ neurone, passes over to another, if the two have some time been simultaneously activated… It follows in the terms of our theory that [energy] passes more easily from an active neurone to another activate neurone than to an inactive one. [Q14, Freud, 1895, p. 319]
  • “[A]n organisation has been formed in ψ whose presence interferes with the passage [of energy]… This organisation is called the ‘ego’. It can easily be depicted if we consider that the regularly repeated reception of endogenous [activity] in certain neurones and the facilitating effect proceeding thence will produce a group of neurones which is constantly [activated] and this corresponds to the vehicle of the store required by the secondary function. Thus, the ego is to be defined as the totality of the ψ [activity], at any given time, in which a permanent component is distinguished from a changing one.” [Q15, Freud, 1895, p. 323a]
  • It is easy to see that the facilitations between the ψ neurones are a part of the ego’s possessions, as representing possibilities, if the ego is altered, for determining its extent in the next few moments. Q16, [Freud, 1895, p. 323b]
  • Let us picture the ego as a network of activated neurones well facilitated in relation to one another. [Q17, Freud, 1895, p. 323c]
  • If an ego exists, it must inhibit psychical primary processes. [Q18, Freud, 1895, p. 324]
  • It is probably the ω neurones which furnish this indication: the indication of reality. In the case of every external perception a qualitative excitation occurs in ω, which in the first instance, however, has no significance for ψ. It must be added that the ω excitation leads to ω discharge and information of this, as of every discharge, reaches ψ. The information of the discharge from ω is thus the indication of quality or reality for ψ. [Q19, Freud, 1895, p. 325]
  • Indication of quality follows, if it comes from outside, whatever the intensity of the activation, whereas if it comes from ψ, it does so only when there are large intensities. It is accordingly inhibition by the ego which makes possible a criterion for distinguishing perception and memory. Biological experience will then teach that discharge is not to be initiated till the indication of reality has arrived, and that with this in view the activation of the desired memories in not to be carried out beyond a certain amount. [Q20, Freud, 1895, p. 326a]
  • On the other hand, the excitation of the ω neurones can also serve to protect the ψ system in the second case: that is, by drawing the attention of ψ to the fact of a perception being present of absent: For this purpose it must be assumed that the ω neurones are originally linked anatomically with the paths of conduction from the various sense-organs and that they direct their discharge back to the motor apparatuses belonging to the same sense organs. In that case the information of the latter discharge (the original reflex attention) will act to ψ biologically as a signal to send out a quantity of energy in the same directions. [Q21, Freud 1895, p. 326b]
  • So then: if there is inhibition by an active ego, the indications of ω discharge become quite generally indications of reality which ψ learns, biologically, to make use of. If, when an indication of reality of the kind emerges, the ego is in a state of wishful tension, it will allow discharge towards the specific action to follow. If an increase of unpleasure coincides with the indication of reality, then ψ will, by means of [lateral connections or local inhibition] of suitable magnitude, institute a defence of normal magnitude at the point indication. [Q22, Freud, 1895, p. 326c]
  • [Wishful discharges] to the point of hallucination and complete generation of unpleasure which involves a complete expenditure of defence are described by us as psychical primary processes; by contrast, those processes which are only made possible by a good engagement of the ego, and which represent a moderation in the foregoing, and are described as psychical secondary processes. It will be seen that the necessary preconditions of the latter is a correct employment of the indications of reality, which is only possible when there is inhibition by the ego. [Q23, Freud, 1895, p. 326-327]
  • Perceptual activations are never activations of single neurones but always of complexes. [Q24, Freud, 1895, p. 327b]
  • Judging is a ψ process which is only made possible by inhibition by the ego and which is evoked by the dissimilarity between the [wishful notion] of a memory and a perceptual activation that is similar to it. It can be inferred from this that coincidence between the two cathexes becomes a biological signal for ending the act of thought… Their non-coincidence [or non-concordance] gives the impetus for the activity of thought, which is terminated once more with their coincidence [or concordance]. [Q25, Freud, 1895, p. 328]
  • Let us suppose, for instance, that the mnemic image wished for [by a child] is the image of the mother’s breast and a front view of its nipple, and that the first perception is a side view of the same object, without the nipple. In the child’s memory there is an experience, made by chance in the course of sucking, that with a particular head-movement the front image turns into the side image. The side image which is now seen leads the head-movement; and experiment shows that its counterpart must be carried out and the perception of the front view is achieved. [Q26, Freud, 1895, p. 328-329]
  • In so far as activations coincide, they give no occasion for activity of thought. On the other-hand, the non-coinciding portions ‘arouse interest’ and can give occasion for activity of thought in two ways. The current is either directed on to the aroused memories and sets an aimless activity of memory at work, which is then moved by differences not similarities, or the current remains in the components of perception which have newly emerged and in that case exhibits an equally aimless activity of judging. [Q27, Freud, 1895, p. 331a]
  • Let us suppose that the object which furnishes the perception resembles the subject – the fellow human being. If so, the theoretical interest taken it is also explained by the fact that an object like this was simultaneously the subject’s first satisfying object and further his first hostile object as well as his sole helping power. For this reason it is in relation to a fellow human-being that a human-being learns to cognize. [Q28, Freud, 1895, p. 331b]
  • Judgment, as will be seen, is not a primary function, but presupposes the activation from the ego of the disparate portions of the perception. [Q29, Freud, 1895, p. 332a]
  • The aim and end of all thought-processes is thus to bring about a state of identity, the conveying of a signal emanating from outside, into a neurone activated from the ego. [Q30, Freud, 1895, p. 332b]
  • While one is perceiving the perception, one copies the movement oneself – that is, one innervates so strongly the motor image of one’s own which is aroused towards coinciding [with the perception], that the movement is carried out. Hence one can speak of a perception having an imitation-value. Or the perception may arouse the mnemic image of a sensation of pain of one’s own, so that one feels the corresponding unpleasure and repeats the appropriate defensive movement. Here we have the sympathy-value of a perception. [Q31, Freud, 1895, p. 333]
  • The process of thought consists in the activation of ψ neurones accompanied by a change, brought about by [lateral or local connections] from the ego… The lateral connections as it were binds a quota of the energy flowing through the neurone. [Q32, Freud 1895, p. 334-335]
  • There is no doubt, however, that the process of thought does leave lasting traces behind it, since a second thinking, a rethinking, calls for so much less expenditure than a first. In order that reality shall not be falsified, therefore, special traces are needed, signs of the processes of thought, constituting a thought-memory which it is not yet possible to shape. [Q33, Freud, 1895, p. 335]
  • It is an important fact that primary processes, such as have been biologically suppressed in the course of ψ development, are daily presented to us during sleep. [Q34, Freud, 1895, p, 336]
  • Accordingly, the precondition for sleep is a lowering of the endogenous load in the ψ nucleus, which makes the secondary process superfluous. In sleep an individual is in an ideal state of inertia, rid of his store of [energy]. In adults, this store is collected in the ‘ego’; we may assume that it is the unloading of the ego which determines and characterises sleep. And here, as is immediately clear, we have the precondition of psychical primary process. [Q35, Freud, 1895, p. 336]
  • Nothing disturbs sleep more than the emergence of sense-impressions, activations entering ψ from φ. [Q36, Freud, 1895, p. 337]
  • If the ego were completely unloaded sleep would be necessarily dreamless. [Q37, Freud, 1895, p. 339]
  • It is interesting furthermore that consciousness in dreams furnishes quality with as little trouble as in waking life. This shows that consciousness does not cling to the ego but can become an addition to any ψ processes. It warns us, too, against possibly identifying primary processes with unconscious ones. Here are invaluable hints for the future! [Q38, Freud, 1895, p. 340]
  • It must be possible for what I have termed the secondary processes to be explained on mechanical lines through the effect produced by a constantly [activate] mass of neurones (the ego) on others with changing [levels of activity]… If I have on the one hand the ego and on the other hand perceptions – that is, activations in ψ coming from φ (from the external world) – then I require a mechanism which causes the ego to follow the perceptions and to influence them. I find it in the fact that, according to my presuppositions, a perception invariably excites ω and thus gives rise to indications of quality. To put it more accurately. It excites consciousness (consciousness of a quality) in ω, and the discharge of the ω excitation will, like every discharge, furnish information to ψ, which is in fact the indication of quality. I therefore put forward the suggestion that it is indications of quality which interest ψ in the perception. This would seem to be the mechanism of psychical attention [Q39, Freud, 1895, p. 360]
  • Attention thus consists in establishing the psychical state of expectation… Attention is biologically justified; it is only a question of guiding the ego as to which expectant activation it is to establish and this purpose is served by the indications of quality. [Q40, Freud, 1895, p. 361]
  • [Speech association] consists in the linking of ψ neurones with neurones which serve sound presentations and themselves have the closest association with motor-speech images. These associations have an advantage of two characteristics over others: they are limited (few in number) and exclusive. In any case, from the sound-image the excitation reaches the word-image and from it reaches discharge. Thus, if the mnemic-images are of such kind that a part-current can go from them to the sound-images and motor-images, then the activation of the mnemic-images is accompanied by information of discharge, which is an indication of quality and also accordingly as indication of the consciousness of the memory. If now the ego preactivates these word-images as it earlier did the images of ω discharge, then it will have created for itself the mechanism which directs the ψ activation to the memories emerging during the passage of energy. This is conscious observing thought. [Q41, Freud, 1895, p. 365]
  • The indications of speech discharge… put thought processes on a level with perceptual processes, lend them reality and make memory of them possible. [Q42, Freud, 1895, p. 366a]
  • Speech-innervation is originally a path of discharge for ψ, operating like a safety-valve, for regulating oscillations in energy; it is a portion of the path to internal change, which represents the only discharge till the specific action has been found. This path acquires a secondary function from the fact that it draws the attention of the helpful person (usually the wished-for object itself) to the child’s longing and distressful state; and thereafter it serves for communication and is thus drawn into specific action. [Q43, Freud, 1895, p. 366b]
  • In virtue of the trend towards imitation, which emerges during judging, it is possible to find the information of movement attaching to this sound-image. This class of memories, too, can now become conscious. It now still remains to associate intentional sounds with the perceptions; after that, the memories when the indications of sound discharge are observed become conscious like perceptions and can be activated from ψ. Thus we have found that it is characteristic of the process of cognitive thought that during it attention is from the first directed to the indications of thought-discharge, to the indications of speech. As is well known, indeed, what is called conscious thought takes place to the accompaniment of slight motor expenditure… [and] if thought is intense… people even speak out loud. [Q44, Freud, 1895, p. 367]
  • The secondary process is characterised by a bound state in the neurone, which though there is a high cathexis, permits only a small current… Now the ego itself is a mass like this of neurones which hold fast to their activity – are, that is in a bound state and this surely can only happen as a result of the effect they have on one another. We can therefore imagine that a perceptual neurone which is active with attention is as a result temporarily, as it were, taken up into the ego and is now subject to the same binding of its energy as are all the other ego neurones… This bound state, which combines high activity with small current, would thus characterise processes of thought mechanically. [Q45, Freud 1895, p. 368]
  • Thus we find ourselves quite unexpectedly before the most obscure problem; the origin of the ego – that is, of a complex of neurones which hold fast to their activity, a complex, therefore, which is for short periods at a constant level… The ego consists originally of the nuclear neurones, which receive endogenous energy though paths of conduction. [Q46, Freud, 1895, p. 369a]
  • The education and development of this original ego take place in a state of craving, in expectation. It learns first that it must not activate motor-images so that discharge results until certain conditions have been fulfilled from the direction of perception. It learns further that it must not activate the wishful idea beyond a certain amount since otherwise it would deceive itself in a hallucinatory manner. If however, it respects these two barriers and directs its attention to the new perceptions, it has a prospect of attaining the satisfaction it is seeking. It is clear, therefore, that the barriers which prevent the ego from activating the wishful-image and the motor-image beyond a certain amount are the ground for the accumulation of energy in the ego and compel it perhaps to transfer its energy within certain limits to the neurones accessible to it. [Q47, Freud, 1895, p. 369b]
  • The whole activated mass is in equilibrium, held on one side by the two barriers against motility and wishing and on the other side by the resistances of the furthest neurones and towards the interior by the constant pressure of the path of conduction. Inside this ego-structure the activation will by no means be everywhere equal; it need only be equal proportionately – that is, in relation to the facilitations [i.e., connections]. [Q48, Freud, 1895, p. 370a]
  • All we can say is that when this barrier was not yet in existence and when motor discharge took place along with the wish, the expected pleasure regularly failed to appear and the continuance of the release of endogenous stimuli finally evoked unpleasure. Only this threat of unpleasure, which came because became attached to premature discharge, can represent the barrier in `question. [Q49, Freud, 1895, p. 370b]
  • Unpleasure remains the only means of education. [Q50, Freud, 1895, 370c]
  • For the ego then, the biological rule of attention runs: If an indication of reality appears, then the perceptual activation which is simultaneously present is to be hyperactivated. [Q51, Freud, 1895, p. 371]
  • It follows from the description of the ego and of its oscillations that the height of the level of its activation too, has no relation to the external world, that a general lowering or raising of it makes no change (normally) in the picture of the world. Since the picture of the world is based on facilitations [i.e., connections] that means that general oscillations of level make no change in the facilitations. A second principle has already been mentioned: namely, that when the level of activity is high, small quantities can be displaced more easily than when it is low. [Q52, Freud, 1895, 372a]
  • Let us go back now to the description of the observing or cognitive process of thought, which is distinguished from the process of expectation by the fact that [in the former] the perceptions do not light upon wishful activations. Thus, in that case the ego is made attentive by the first indications of reality as to which region of perception is to be activated. The passage of association of the energy brought along with them occurs over preactivated neurones and the energy which is displacing itself, can flow on again each time. During this passage of association the indications of quality (of speech) are generated, as a result of which the passage of association becomes conscious and capable of being reproduced. [Q53, Freud, 1895, p. 372b]
  • Indications of discharge through speech are also in a certain sense indications of reality – but of thought-reality not external reality, and in their case a rule of this kind has not by any means come into effect, because no constant threat of unpleasure would be attached to a breach of it. The unpleasure through neglecting cognition is not so glaring as that from ignoring the external world, though at bottom they are one and the same. Thus, there is in fact also an observing process of thought in which indications of quality are either not, or only sporadically, aroused and which is made possible by the fact that the ego follows the passage of association automatically with its activity. This process of thought is in fact far the more frequent, without being abnormal, it is our ordinary thought, unconscious, with occasional intrusions into consciousness – what is known as consciousness thought with unconscious intermediate links, though these can be made conscious. [Q54, Freud, 1895, p. 373]
  • Thought accompanied by an activation of the indications of thought-reality or of the indications of speech is the highest, securest from of cognitive thought process. [Q55, Freud, 1895, p. 374]
  • From this we arrive at a fresh thesis for the mechanical representation of psychical processes: namely, that the passage of association which is not altered by the height of the level of activity [i.e., the amplitude] can be influenced by the energy itself that is in flow. In general, a large [flow of energy] takes different pathways in the network of facilitations than a small one… The arousing of indications of thought seems then to be linked to the passage of small amounts of energy. This is not to assert that any other passage of energy is bound to remain unconscious, since the arousing of indications of speech is not the only method of arousing consciousness. [Q56, Freud, 1895, p. 375]
  • How then can we perhaps give a clear picture of thought that becomes conscious intermittently, of sudden intrusions into consciousness? After all, our ordinary purposeless thought, though it is accompanied by preactivation and automatic attention, attached no importance to indications of thought. It has not been shown biologically that they are indispensable for this process. Nevertheless, they usually emerge (1) if the smooth passage of energy has reached an end or has come up again an obstacle and (2) if it has aroused an idea which, for other reasons, calls up indications of quality – that is, consciousness. At this point the discussion can be broken off. [Q57, Freud, 1895, p. 375-376]
  • The fact that a memory exhibits a hallucinatory characteristic for so long also calls for an explanation – important for our view of hallucination. Here it is plausible to suppose that this capacity for hallucination, as well as the capacity for affect, are indications of the fact that the ego-activation has not yet gained any influence on the memory, that the primary lines of discharge and the full or primary process predominate it. We are obliged to see in the state of hallucinosis a backward flow of energy to φ and to ω, thus a bound neurone does not admit of such a backward flow. [Q58, Freud, 1895, p. 381]
  • Another ground for error may lie in the fact that the perceptions of reality have not been completely perceived because they were not within the range of the senses. These are errors of ignorance which no human being can avoid. Where this determinant does not apply , the psychical preactivation may be defective (owing to the ego being deflected away from perceptions) and inaccurate perceptions and incomplete passages of thought may result. These are errors due to insufficient attention. [Q59, Freud, 1895, p. 384]
  • The ψ processes would in themselves be unconscious and would only subsequently acquire a secondary, artificial consciousness through being linked with processes of discharge and perception (speech association). [Q60, Freud, 1896, p. 389]

Standard Edition, Volume 2. Studies on Hysteria. 1893.


  • Hysterics suffer mainly from reminiscences. [Q61, Freud & Breuer, 1893, p. 7]
  • It appears, that is to say, that these memories correspond to traumas that have not been sufficiently abreacted. [Q62, Breuer & Freud, 1893, p. 10]
  • Throughout the entire illness her two states of consciousness persisted side by side: the primary one in which she was quite normal psychically, and the secondary one which may well be likened to a dream in view of the wealth of imaginative products and hallucinations, its… lack of inhibition and control in its associations. [Q63, Breuer & Freud, 1893, p.45a]
  • Every one of her hypnoses in the evening afforded evidence that the patients was entirely clear headed and well-ordered in her mind and normal as regards her feeling and volition so long as none of the products of her secondary state was acting as a stimulus in the unconscious. The extremely marked psychosis which appeared whenever there was any considerable interval in this unburdening process showed the degree to which those products influenced the psychical events of her ‘normal state’. It is hard to avoid expressing the situation by saying that the patient was split into two personalities. [Q64, Breuer & Freud, 1893, p. 45b]
  • [A]nything which powerfully recalled any of her traumas brought her into a state of delirium. In such states – and the few observations I made led me to no other conclusion – there was a limitation of consciousness and a compulsion to associate similar to that prevailing in dreams; hallucinations and illusions were facilitated to the highest degree and … even nonsensical inferences were made. This state… might be regarded as an acute psychosis (serving as the equivalent of an attack) which could be classified as a condition of ‘hallucinatory confusion’. [Q65, Breuer & Freud, 1893, p. 96]
  • The actual traumatic moment, then, is the one at which the incompatibility forces itself upon the ego and at which the latter decides on the repudiation of the incompatible idea. That idea is not annihilated by a repudiation of the kind but merely repressed into the unconscious. When this process occurs for the first time there comes into being a nucleus and centre of crystallisation for the formation of a psychical group divorced from the ego. [Q66, Breuer & Freud, 1893, p. 123a]
  • If the perceptual organ is excited by a mnemic image, we must suppose that that organ’s excitability has been changed in an abnormal direction, and that this change is what makes hallucination possible. [Q66b, Breuer & Freud, 1893, p. 189]
  • How has it come about that we speak of someone who has been slighted as having been “stabbed in the heart”? All these sensations and innervations belong to the field of “The Expression of the Emotions’, which, as Darwin taught us , consists of actions which originally had an action and purpose. These may now for the most part have become so much weakened that the expression of them in words seems to us only to be a figurative picture of them, whereas in all probability the description was once meant literally. [Q67, Breuer & Freud, 1893, p. 181]
  • Let us imagine a man in a state of intense expectation, which is not, however, directed to any particular sensory field. We then have before us a brain which is quiescent but prepared for action. We may rightly suppose that in such a brain all paths of conduction are at maximum of their conductive capability – that they are in a state of tonic excitation. It is significant fact that in ordinary language we speak of such a state as one of tension. [Q68, Breuer & Freud, 1893, p. 194-5]
  • And here for the first time we meet the fact that there exists in the organism a tendency to keep intracerbral excitation constant. [Q69, Breuer & Freud, 1893, p. 197]
  • We have spoken of a tendency on the part of the organism to keep tonic cerebral excitation constant. [Q70, Breuer & Freud, 1893, p. 198]
  • The affect of anxiety entered into her reverie and created a hypnoid state… This was repeated on different occasions and the ideational content gradually became richer and richer. [Q71, Breuer & Freud, 1893, p. 235]
  • It is true that ‘unconscious ideas’ never, or only rarely and with difficulty, enter waking thought; but they influence it. They do so, first, through their consequences – when, for instance, a patient is tormented by a hallucination… So particular groups of ideas constantly force themselves on the patient with a certain amount of compulsion and he is obliged to think of them. [Q72, Breuer & Freud, 1893, p. 237]
  • Any event that provokes unconscious memories liberates the whole affective force of these ideas that have not undergone a wearing away, and the affect that is called up is then quite out of proportion to any that would have arisen in the conscious mind alone. [Q73, Breuer & Freud, 1893, p. 238a]
  • While she was in this state her waking thought was without energy, her judgment was childish and she seemed, as I have said positively imbecile. I believe that this was due to the fact that waking thought has less energy at its disposal if a great amount of psychical excitation is appropriated by the unconscious. [Q73b, Breuer & Freud, 1893, p. 238b]

Standard Edition, Volume 3. Early Psychoanalytic Publications. 1893.


  • Something in his nervous system which we will for the moment call the sum of excitation is increased. Now in every individual there exists a tendency to diminish this sum of excitation once more, in order to preserve his health. [Q74, Freud, 1893b, p.36a]
  • Psychical trauma is linked with an increase in the sum of excitation in his nervous system. [Q75, Freud, 1893b, p. 36b]
  • The man who first flung a word of abuse at his enemy instead of a spear was the founder of civilisation. [Q76, Freud, 1893b, p. 36c]
  • If someone with a disposition to neurosis lacks the aptitude for conversion [to hysteria], but if, nevertheless, in order to fend off an incompatible idea, he sets about separating it from its affects, then that affect is obliged to remain in the psychical sphere. The idea now weakened, is still left in consciousness, separated from all association. But its affect, which has become free, attaches itself to other ideas which are not in themselves incompatible; and thanks to this ‘false connection’, those ideas turn into obsessional ideas. [Q77, Freud, 1893b, p.52]
  • Here, the ego rejects the incompatible idea together with its affect and behaves as if the idea had never occurred to the ego at all. But from the moment at which this has been successfully done the subject is in a psychosis, which can only be classified as ‘hallucinatory confusion’. [Q78, Freud, 1893b, p. 58]
  • I refer to the concept that in mental functions something is to be distinguished – a quota of affect or sum of excitation – which possesses all the characteristics of a quantity (though we have no means of measuring it) which is capable of increase, diminution, displacement and discharge and which is spread over the memory-traces of ideas somewhat as an electric charge is spread over the surface of the body. This hypothesis… can be applied in the same sense as physicists apply the hypothesis of a flow of electric fluid. It is provisionally justified by its utility in co-ordinating and explaining a great variety of psychical states. [Q79, Freud, 1893b, p. 60-61]
  • The affect is a state which passes rapidly, the neurosis is a chronic one; because, while exogenous excitation operates with a single impact, the endogenous excitation operates as a constant force. In neurosis, the nervous system is reacting against a source of excitation which is internal, whereas in the corresponding affect it is reacting against an analogous source of excitation which is external. [Q80, Freud, 1895b, p. 112]
  • The action of heredity is comparable to that of a multiplier in an electric circuit, which exaggerates the visible deviation of the needle, but which cannot determine its direction. [Q81, Freud, 1896, p. 147]
  • It looks as though the difficulty of disposing of a present impression, the impossibility of transforming it into a powerless memory, is attached precisely to the character of the psychical unconscious. [Q82, Freud, 1896b, p. 219]
  • If we put the hysteric under hypnosis and lead his thoughts back to the time at which the symptom in question first appeared, memory of a psychical trauma (or series of traumas) belonging to that time awakens in him with hallucinatory vividness, the symptom having persisted as a mnemic symbol of the trauma. Thus hysterics suffer mainly from reminiscences. [Q83, Freud, 1893c, p. 244]
  • It seems that in man the sexual instinctual forces are meant to be stored up so that on their release at puberty they may serve great cultural end. [Q84, Freud, 1898, p. 281]
  • What is recorded as a mnemic image is not the relevant experience itself – in this respect the resistance gets its way; what is recorded is another psychical element closely associated with the objectionable one. [Q85, Freud, 1899, 307]
  • Close investigation shows rather that these falsifications of memory are tendentious – that is, that they serve the purposes of the repression and replacement of the objectionable or disagreeable impressions. [Q86, Freud, 1899, p. 322]

Penguin, Volume 4. The Interpretation of Dreams. 1900. Covers volumes 4 & 5 of Standard Edition.

  • Thomayer (1896) draws attention to certain anxiety dreams which he thinks should be regarded as equivalents of epileptic fits. [Q87, Freud, 1900, p. 161]
  • Krauss (1859) declares that ‘insanity is a dream dreamt while the senses are awake’. [Q88, Freud, 1900, p. 162a]
  • Schopenhauer (1862) calls dreams a brief madness and madness a long dream. [Q89, Freud, 1900, p. 162b]
  • The rapid sequence of ideas in dreams is paralleled by the flight of ideas in psychoses. In both there is a complete lack of sense of time. [Q90, Freud, 1900, p. 164]
  • We may therefore suppose that dreams are given their shape in individual human beings by the operation of two psychical forces (or we may describe them as currents or systems). [Q91, Freud, 1900, p. 225]
  • The psychical process which we have found at work in dream-displacement, though it cannot be described as a pathological disturbance, nevertheless differs from the normal and is to be regarded as a process of a more primary nature. [Q92, Freud, 1900, p. 264]
  • Our attention is thus drawn to the fact that in considering the suppressed and suppressing agencies, we must not regard their relation as being exclusively one of mutual inhibition. Just as much regard must be paid to cases in which the two agencies being about a pathological effect by working side by side and by intensifying each other. [Q93, Freud, 1900, p. 618]
  • The mind endeavours to carry upon these incoherent trains of hallucinations the same work of logical co-ordination that it carries out upon sensations during the day-time. It connects up all these detached images by an imaginary link and stops up any excessively wide gaps between them. [Q94, Freud, 1900, p. 644]
  • We describe the system that lies behind [the ego] as ‘the unconscious’. Because it has no access to consciousness except via [the ego]. [Q95, Freud, 1900, p. 690-691a]
  • We shall take the unconscious system as the starting point of dream formation. Like other thought structures, this dream instigator will make an effort to advance into [the ego] and from there to obtain consciousness. [Q96, Freud, 1900, p.691b]
  • The only way we can describe what happens in hallucinatory dreams is by saying that the excitation moves in a backward Instead of being transmitted towards the motor end of the apparatus it moves towards the sensory end and finally reaches the perceptual system. If we describe as ‘progressive’ the direction taken by psychical processes arising from the unconscious during waking life, then we may speak of dreams as having a ‘regressive’ character. This regression, then, is undoubtedly one of the psychological characteristics of the process of dreaming; but we must remember that it does not occur only in dreams. Intentional recollection and other constituent processes of our normal thinking involve a retrogressive movement in the psychical apparatus from a complex ideational act back to the raw material of the memory traces underlying it. In the waking state, however, this backward movement never extends beyond the mnemic images; it does not succeed in producing a hallucinatory revival of the perceptual images. [Q97, Freud, 1900, p. 692]
  • We call it regression when in a dream an idea is turned back into the sensory image from which it was originally derived. [Q98, Freud, 1900, p. 693]
  • In explaining regression in dreams, however, we must bear in mind the regressions which also occur in pathological waking states. My explanation of hallucinations in hysteria and paranoia and of visions in mentally normal subjects is that they are in fact regressions – that is, thoughts transformed into images. [Q99, Freud, 1900, p. 693]
  • Three kinds of regression are to be distinguished: (a) topographical regression, in the sense of the schematic picture of the ψ-systems which we have explained above; (b) temporal regression, in so far as what is in question is harking back to older psychical structures; and (c) formal regression, where primitive methods of expression and representation take the place of the usual ones. All these kinds of regression are however, one at bottom and occur together as a rule; for what is older in time is also more primitive in form and in psychical topography lies nearer to the perceptual end. [Q100, Freud, 1900, p. 699]
  • Dreaming is on the whole an example of regression to the dreamer’s earliest conditions, a revival of his childhood, of the instinctual impulses which dominated it and of the methods of expression which were available to him. Behind this childhood of the individual we are promised a picture of a phylogenetic childhood – a picture of the development of the human race. [Q101, Freud, 1900, p. 699b]
  • Psycho-analysis may claim a high place among the sciences which are concerned with the reconstruction of the earliest and most obscure periods of the beginnings of the human race. [Q102, Freud, 1900, p. 700]
  • Dreams which fulfil their wishes along the short path of regression have merely preserved for us in that respect a sample of the psychical apparatus’s primary method of working, a method which was abandoned as being inefficient. What once dominated waking life while the mind was still young and incompetent seems now to have been banished into the night – just as the primitive weapons, the bows and arrows that have been abandoned by adult men, turn up once more in the nursery. Dreaming is a piece of infantile mental life that has been superseded. [Q103, Freud, 1900, p. 721]
  • If such thing as a system Ucs [i.e., unconscious] exists… dreams cannot be its only manifestation. [Q104, Freud, 1900, p. 723]
  • Indeed it is a prominent feature of the unconscious processes that they are indestructible. In the unconscious nothing can be brought to an end, nothing is past and forgotten. [Q105, Freud, 1900, p. 733]
  • What performs this work is the [ego] and psychotherapy can pursue no other course than to bring the Ucs under the domination of the [ego]. [Q106, Freud, 100, p. 934]
  • Dreaming has taken on the task of bringing back under the control of the [ego] the excitation in the Ucs which has been left free; in so doing, it discharges the Ucs excitation, serves it as a safety valve. [Q107, Freud, 1900, p. 735]
  • If, therefore, the activation from the ego ceases, the danger is that the unconscious excitations may release affect of a kind which (as a result of the repression which has already occurred) can only be experienced as unpleasure, as anxiety. [Q108, Freud, 1900, p. 739]
  • The activity of the second system [the ego], constantly feeling its way and alternately sending our and withdrawing [energy]. Need on the one hand to have the whole of the material of memory freely at its command; but on the other hand it would be an unnecessary expenditure of energy if it sent out large quantities of energy along the various paths of thought and thus caused them to drain away to no useful purpose and diminish the quality available for altering the external world. I therefore postulate that for the sake of efficiency the second system succeeds in retaining the major part of the energy in a state of quiescence and in employing only a small part on displacement. The mechanisms of these processes are quite unknown to me; anyone who wished to take these ideas seriously would have to look for physical analogies to them and find a means of picturing the movements that accompany excitations of neurones. All that I insist upon in the idea that the activity of the first ψ-system [the id] is directed towards securing the free discharge of the quantities of excitation, while the second system [the ego] by means of the projections emanating from it, succeeds in inhibiting the discharge and in transforming the energy into a quiescent one, no doubt with a simultaneous raising of its level. [Q109, Freud, 1900, p. 758-759]
  • The regular avoidance by the psychical process of the memory of anything that had once been distressing affords us the prototype and first example of psychical repression. It is a familiar fact that much of this avoidance of what is distressing – this ostrich policy – is still to be seen in the normal mental life of adults. [Q110, Freud, 1900, p. 760]
  • The [ego] can only activate an idea if it in a position to inhibit any development of unpleasure that may proceed from it. [Q111, Freud, 1900, p. 761]
  • I propose to describe the psychical process of which the first system [the id] alone admits as the primary process; and the process which results from the inhibition imposed by the second system [the ego] as the secondary process. [Q112, Freud, 1900, p. 761b]
  • When I described one of the psychical processes occurring in the mental apparatus as the primary one, what I had in mind was not merely considerations of relative importance and efficiency; I intended also to choose a name which would give an indication of its chronological priority. It is true that so far as we know, no psychical apparatus exists which possesses a primary process only and that such an apparatus is to that extent theoretical fiction. But this much is a fact: the primary processes are present in the mental apparatus from the first, while it is only during the course of life that the secondary processes unfold and come to inhibit and overlay the primary ones; it may even be that their complete domination is not attained until the prime of life. In consequence of the belated appearance of the secondary processes, the core of our being, consisting of unconscious wishful impulses, remains inaccessible to the understanding and inhibition of the [ego], the part played by the latter is restricted once and for all to directing along the most expedient paths the wishful impulses than arise from the unconscious. [Q113, Freud, 1900. p. 763]
  • The increase in activity which becomes necessary when these primary modes of functioning are inhibited is to be found in the fact that we produce a comic effect, that is, a surplus of energy which has to be discharged in laughter, if we allow these modes of thinking to force their way through into consciousness. [Q114, Freud, 1900, p. 766]
  • The interpretation of dreams in the royal road to a knowledge of the unconscious activities of the mind. [Q115, Freud, 1900, p. 769]
  • I hope to be able to show elsewhere how the compounding of the apparatus out of two agencies makes it possible for the normal mind too to function with greater delicacy than would be possible with only one of them. [Q116, Freud, 1900, p. 769]
  • I consider it expedient and justifiable to continue to make use of the figurative image of the two systems. We can avoid any possible abuse of this method of presentation by recollecting that ideas, thoughts and the psychical structures in general must never be localised in organic elements of the nervous system but rather, as one might say, between them, where resistances and facilitations provide the corresponding correlates. [Q117, Freud, 1900, p. 771]
  • The problem of the unconscious in psychology is, in the forcible words of Lipps (1897), less a psychological problem than the problem of psychology. [Q118, Freud, 1900, p. 772]
  • The unconscious must be assumed to be the general basis of psychical life. The unconscious is the larger sphere, which includes within it the smaller sphere of the conscious. Everything conscious had an unconscious preliminary stage; whereas what is unconscious may remain at that stage and nevertheless claim to be regarded as having the full value of a psychical process. The unconscious is the true psychical reality; in its innermost nature it is as much unknown to us as the reality of the external world, and it is as incompletely presented by the data of consciousness as is the external world by the communication of our sense organs. [Q119, Freud, 1900, p. 773]


  • We have described the relations of the two systems to each other and to consciousness by saying that the [ego] stands like a screen between the [id] and consciousness. [Q120, Freud, 1900, p. 776]

Standard Edition, Volume 6. The Psychopathology of Everyday Life. 1901.


  • It may be surmised that the architectonic principle of the mental apparatus lies in a stratification – a building up of superimposed agencies. [Q121, Freud, 1901, p. 147]
  • It is in my view wrong to call the feeling of having experienced something before an illusion. It is rather that at such moments something is really touched on which we have already experienced once before, only we cannot consciously remember it because it has never been conscious. To put it briefly, the feeling of déjà vu corresponds to the recollection of an unconscious fantasy. There exist unconscious fantasies (or day-dreams) just as there exist conscious creations of the same kind which everybody knows from his own experience. [Q122, Freud, 1901, p. 266]
  • The unconscious is quite timeless. [Q123, Freud, 1901, p. 275]

Standard Edition, Volume 7. A Case of Hysteria, Three Essays on Sexuality. 1901-1905.


  • Ontogenesis may be regarded as a recapitulation of phylogenesis [Q124, Freud, 1905, p. 131]
  • By an “drive” is provisionally to be understood the psychical representative of an endosomatic, continuously flowing source of stimulation as contrasted with stimulus, which is set up by single excitations coming from without. [Q125, Freud, 1905, p. 168]
  • It is noticeable that writers who concern themselves with explaining the characteristics and reactions of the adult have devoted much more attention to the primeval period which is comprised in the life of the individual’s ancestors – have, that is, ascribed much more influence to heredity – than to the other primeval period, which falls within the lifetime of the individual himself – that is, to childhood. One would have supposed that the influence of the this latter period would be easier to understand and could claim to be considered before that of heredity. [Q126, Freud, 1905, p. 173]
  • It is during this period of total or only partial latency that are built up the mental forces which are later to impede the course of the sexual instinct and, like dams, restrict its flow – disgust, feelings of shame and the claims of aesthetics and moral ideals. One gets an impression from civilised children that the construction of these dams is a product of education and no doubt education has much to do with it. But in reality this development is organically determined and fixed by heredity. [Q127, Freud, 1905, p. 177]
  • We have defined the concept of libido as a quantitatively variable force… We this, reach the idea of a quantity of libido, to the mental representation of which we give the name ‘ego-libido’, and whose production, increase or diminution, distribution and displacement should afford us possibilities for explaining the psychosexual phenomena observed. [Q128, Freud, 1905, p. 217]
  • Narcissistic or ego-libido seems to be the great reservoir from which the object-activations are sent out and into which they are withdrawn once more; the narcissistic libidinal activation of the ego is the original state of things, realised in earliest childhood and is merely covered by the later extrusions of libido but in essential persists in them. [Q129, Freud, 1905, p. 128]

Standard Edition, Volume 8. Jokes and their Relation to the Unconscious. 1905.


  • The hearer of the joke laughs with the quota of psychical energy which has become free through the lifting of the inhibitory activation; we might say that he laughs this quota off. [Q130, Freud, 1905, p. 149]
  • For the euphoria we endeavour to reach by these means is nothing other than the mood of a period of life in which we were accustomed to deal with our psychical work in general with a small expenditure of energy – the mood of our childhood, when we were ignorant of the comic, when we were incapable of jokes and when we had no need of humour to make us feel happy in our life. [Q131, Freud, 1905, p. 236]

Standard Edition, Volume 9. Jensen’s ‘Gradiva’ and Other Works. 1906-1908.


  • ‘Repressed’ is a dynamic expression, which takes account of the interplay of mental forces; it implies that there is a force present which is seeking to bring about all kinds of psychical effects, including that of becoming conscious. The mark of something repressed is precisely that in spite of its intensity it is unable to enter consciousness. [Q132, Freud, 1907, p. 48]
  • Science does not as yet suspect the importance of repression, it does not recognise that in order to explain the world of psychopathological phenomena the unconscious is absolutely essential. [Q133, Freud, 1907, p. 53]
  • For during sleep, along with a general lowering of mental activity, there is a relaxation in the strength of the resistance with which the dominant psychical forces oppose what is repressed. It is this relaxation that makes the formation of dreams possible, and that is why dreams give us our best access to a knowledge of the unconscious part of the mind. [Q134, Freud, 1907b, p. 62-65]
  • A deeper insight into the mechanism of obsessional neurosis is gained if we take into account the primary fact which lies at the bottom of it. This is always the repression of an instinctual impulse… The influence of the repressed impulse is felt as a temptation and during the process of repression itself anxiety is generated, which gains control over the future in the form of expectant anxiety. The process of repression which leads to obsessional neurosis must be considered as one which only partly successful and which increasingly threatens to fail. It may this be compared to an unending conflict; fresh psychical efforts are continually required to counterbalance the forward pressure of the impulse. [Q135, Freud, 1907b, p. 124]

Standard Edition, Volume 10. Two Case Histories: ‘Little Hans’ and the ‘Rat Man’. 1909.


  • I then made some short observation upon the psychological differences between the conscious and the unconscious, and upon the fact that everything conscious was subject to the process of wearing-away, while what was unconscious was relatively unchangeable. [Q136, Freud, 1909, p. 176]
  • He has said to himself, he went on, that a self-reproach could only arise from a breach of a person’s own inner moral principles and not from that of any external ones. I agreed, and said that the man who merely breaks an external law often regards himself as a hero. Such an occurrence, he continued, was thus only possible where disintegration of the personality was already present. Was there a possibility of his effecting a re-integration of his personality? …The moral self was the conscious, the evil self was the unconscious. He then said that, though he considered himself a moral person, he could quite definitely remember having done things in his childhood which came from his other self. I remarked that here he had incidentally hit upon one of the chief characteristics of the unconscious, namely its relation to the infantile. The unconscious, I explained, was the infantile; it was that part of the self which had become separated off from it in infancy, which had not shared the later stages of its development, and which had in consequence become repressed. It was the derivatives of this repressed unconscious that were responsible for the involuntary thoughts which constituted his illness. [Q137, Freud, 1909, p. 177-178]
  • The chronic coexistence of love and hatred, both directed towards the same person and both of the highest degree of intensity, cannot fail to astonish us… The necessary condition for the occurrence of such a strange state of affairs in a person’s erotic life appears to be that at a very early age, somewhere in the prehistoric period of his infancy, the two opposites should have been split apart and one of them, usually hatred, have been repressed. If we consider a number of analyses of obsessional neurotics we shall find it impossible to escape the impression that a relation between love and hatred such as we have found in our present patient is among the most frequent, the most marked, and probably, therefore, the most important characteristics of obsessional neurosis. [Q138, Freud, 1909, p. 239]


Standard Edition, Volume 11. Five Lectures on Psycho-Analysis, Leonardo Da Vinci and Other Works. 1910.


  • The explanation of this fact would be a most awkward business, were ti not that the way is pointed by experiences and experiments in hypnotism. The study of hypnotic phenomena has accustomed us to what was at first a bewildering realisation that in one and the same individual there can be several mental groupings, which can remain more or less independent of one another, which can know nothing of one another and which can alternate with one another on their hold on consciousness. [Q139, Freud, 1910, p. 19]
  • You will also learn with astonishment from the analysis of dreams (and most convincingly from your own) what an unsuspectedly great part is played in human development by impressions and experiences of early childhood. [Q140, Freud, 1910, p. 36]
  • Anxiety is one of the ego’s reactions in repudiation of repressed wishes. [Q141, Freud, 1910, p. 37]
  • We have become aware in our opponents, just as we do in our patients, that their power of judgement is very noticeably influenced affectively… The arrogance of consciousness (in rejecting dreams with such contempt, for instance) is one of the most powerful of the devices with which we are provided as a universal projection against the incursion of unconscious complexes. That is why it is so hard to convince people of the reality of the unconscious and to teach them to recognise something new which in contradiction to their conscious knowledge. [Q142, Freud, 1910, p. 39]
  • Even before puberty extremely energetic repressions of certain instincts have been effected under the influence of education, and mental forces such as shame, disgust and morality have been set up, which like watchmen, maintain these repressions. So that when at puberty the high tide of sexual demands is reached, it is met by these mental reactive or resistant structures like dams. [Q143, Freud, 1910, p. 45]
  • Withdrawal from reality is the main [functional] purpose of [mental] illness but also the main damage caused by it. [Q144, Freud, 1910, p. 49]
  • Drives and their transformations are at the limit of what is discernable by psycho-analysis. From that point it gives place to biological research. [Q145, Freud, 1910, p. 136]
  • You cannot exaggerate the intensity of people’s inner lack of resolution and craving for authority. The extraordinary increase in neurosis since the power of religions has waned may give you a measure of it. The impoverishment of the ego due to the large expenditure of energy on repression demanded of every individual by civilisation may be one of the principal causes of this state of things. [Q146, Freud, 1910, p. 146]

Standard Edition, Volume 12. Case Histories of Schreber, Papers on Technique and Other Works. 1911-1913.


  • The turning away of libido from the external world is a particularly clearly-marked feature in dementia praecox. [Q147, Freud, 1911, p. 77]
  • The shortening of analytic treatment is a justifiable wish, and its fulfilment, as we shall learn, is being attempted along various lines. Unfortunately, it is opposed by a very important factor, namely, the slowness with which deep-going changes in the mind are accomplished – in the last resort, no doubt, the ‘timelessness’ of our unconscious processes. [Q148, Freud, 1911, p. 130]
  • The working through of the resistances may in practice turn out to be an arduous task for the subject of the analysis and a trial of patience for the analyst. Nevertheless it is part of the work which effects the greatest changes in the patient and which distinguishes analytic treatment from any kind of treatment by suggestion. From a theoretical point of view one may correlate it with the ‘abreacting’ of the quotas of affect strangulated by repression – an abreaction without which hypnotic treatment [is] ineffective. [Q149, Freud, 1911, p. 156]
  • Psycho-analytic treatment is founded on truthfulness. In this fact lies a great part of its educative effect and its ethical value. It is dangerous to depart from this foundation. Anyone who has become saturated in the analytic technique will no longer be able to make use of the lies and pretences which a doctor normally finds unavoidable; and if, with the best of intentions, he does attempt to do so, he is very likely to betray himself. [Q150, Freud, 1911, p. 164]
  • In the psychology which is founded on psycho-analysis we have become accustomed to taking as our starting point the unconscious mental processes, with the peculiarities of which we have become acquainted through analysis. We consider these to be the older primary processes, the residues of a phase of development in which they were the only kind of mental processes. [Q151, Freud, 1911b, p. 219]
  • I shall be returning to lines of thought which I have developed elsewhere when I suggest that the state of psychical rest was originally disturbed by the peremptory demands of internal needs. When this happened, what was thought of was simply presented in a hallucinatory manner, just as still happens today with our dream-thoughts every night. [Q152, Freud, 1911b, p. 219]
  • The increased significance of the external world [in our ontogenetic/phylogenetic development] heightened the importance too of the sense-organs that are directed towards that external world, and of the consciousness attached to them. Consciousness now learned to comprehend sensory qualities in addition to the qualities of pleasure and pain which hitherto had alone been of interest to it. A special function was instituted which had periodically to search the external world, in order that its data might be familiar already if an urgent internal need should arise – the function of attention. Its activity meets the sense impressions half-way, instead of awaiting their appearance. [Q153, Freud, 1911b, p. 220]
  • Restraint upon motor discharge (upon action), which then became necessary, was provided by means of the process of thinking, which was developed from the presentation of ideas. Thinking was endowed with characteristics which made it possible for the mental apparatus to tolerate an increased tension of stimulus while the process of discharge was postponed. It is essentially an experimental kind of acting, accompanied by displacement of relatively small quantities of energy together with less expenditure (discharge) of them. For this purpose the conversion of freely displaceable energy into ‘bound’ energy was necessary, and this was brought about by means of raising the whole level of the energetic process. [Q154, Freud, 1911b, p. 221]
  • A general tendency of our mental apparatus, which can be traced back to the economic principle of saving expenditures of energy, seems to find expression in the tenacity with which we hold on to the sources of pleasure at out disposal, and in the difficulty with which we renounce them. With the introduction of the reality principle ones species of thought activity was split off; it was kept free from reality-testing and remained subordinated to the pleasure principle alone. This activity is fantasising, which begins already in children’s play, and later, continued as day-dreaming, abandons dependence on real objects. [Q155, Freud, 1911b, p. 222]
  • Religions have been able to effect absolute renunciation of pleasure in this life by means of the promise of compensation in a future existence; but they have not by this means achieved a conquest of the pleasure principle. It is science which comes nearest to succeeding in that conquest [Q156, Freud, 1911b, p. 224]
  • Frustration has a pathogenic effect because it dams up libido, and so submits the subject to a test as to how long he can tolerate this increase in psychical tension and as to what methods he will adopt for dealing with it. [Q157, Freud, 1912, p. 232]
  • The immediate effect of frustration lies in its bringing into play the dispositional factors which have hitherto been inoperative. Where these are present and sufficiently strongly developed, there is a risk of the libido becoming introverted. It turns away from reality, which owing to the obstinate frustration, has lost its value for the subject, and turns towards the life of fantasy. [Q158, Freud, 1912, p. 232b]
  • As a result of their having reached a particular period of life, and in conformity with regular biological processes, the quantity of libido in their mental economy has experienced an increase which is in itself enough to upset the equilibrium of their health and to set up the necessary conditions for a neurosis. It is well known that more of less sudden increases of libido of this kind are habitually associated with puberty and the menopause… Here the damming-up of libido is the primary factor; it becomes pathogenic as a consequence of a relative frustration on the part of the external world… We may assume that it is not a question of an absolute quantity but of the relation between the quota of libido in operation and the quantity of libido which the individual ego is able to deal with that is, to hold under tension, to sublimate or to employ directly. For this reason a relative increase in the quantity of libido may have the same effect as an absolute one. [Q159, Freud, 1912, p. 236]
  • Unconsciousness seemed to us at first only an enigmatical characteristic of a definite psychical act. Now it means more for us. It is a sign that this act partakes of the nature of a certain psychical category known to us by other and more important characters and that it belongs to a system of psychical activity which is deserving of our fullest attention. The index-value of the unconscious has far outgrown its importance as a property. The system revealed by the sign that the single acts forming parts of it are unconscious we designate by the name ‘The Unconscious’, for want of a better and less ambiguous term. In German, I propose to denote this system by the letters Ubw an abbreviation of the German word ‘Unbewusst’. And this is the third and most significant sense which the term ‘unconscious’ has acquired in psycho-analysis. [Q160, Freud, 1912, p. 266]
  • The characteristics peculiar to both [schizophrenia and paranoia] – megalomania, turning away from the world of objects, increased difficulty in transference – have obliged us to conclude that their dispositional fixation is to be looked for in a stage of libidinal development before object-choice has been established – that is in the phase of auto-erotism and of narcissism. [Q161, Freud, 1912, p. 318]

Standard Edition, Volume 13. Totem and Taboo and Other Works. 1913-1914.


  • It might be maintained that a case of hysteria is a caricature of a work of art, that an obsessional neurosis is a caricature of a religion and that a paranoid delusion is a caricature of a philosophical system. [Q162, Freud, 1913, p. 73]
  • Although we are not yet in a position to describe with sufficient accuracy the characteristics of this narcissistic stage, at which the hitherto dissociated sexual impulses come together into a signal unity and activate the ego as an object, we suspect already that this narcissistic organisation is never wholly abandoned. A human being remains to some extent narcissistic even after he has found external objects for his libido. The activation of objects which he effects are as it were emanations of the libido that still remains in his ego and can be drawn back into once more. The state of being in love, which is psychologically so remarkable and is the normal prototype of the psychoses, shows these emanations at their maximum compared to the level of self-love. [Q162, Freud, 1913, p. 89]
  • The animistic phase would correspond to narcissism both chronologically and in its content; the religious phase would correspond to the stage of object-choice of which the characteristic is a child’s attachment to his parents; while the scientific phase would have an exact counterpart in the stage at which an individual has reached maturity, has renounced the pleasure principle, adjusted himself to reality and turned to the external world for the object of his desires. [Q163, Freud, 1913, p. 90]
  • Psychoanalysis points to psychology for the solution of a good half of the problems of psychiatry. It would nevertheless be a serious mistake to suppose that analysis favours or aims at a purely psychological view of the mental disorders. It cannot overlook the fact that the other half of the problems of psychiatry are concerned with the influence of organic factors on the mental apparatus. Even in the case of the mildest of these disorders, the neuroses, it makes no claim that their origin is purely psychogenic but traces their aetiology to the influence upon mental life of an unquestionable organic factor. [Q164, Freud, 1913, p. 175]
  • Thus it is part of the nature of the mental past that, unlike the historic past, it is not absorbed by its derivatives; it persists (whether actually or only potentially) alongside what has proceeded from it. The proof of this assertion lies in the fact that the dreams of normal people revive their childhood characters every night and reduce their whole mental life to an infantile level. The same return to psychical infantilism (regression) appears in the neuroses and psychoses, whose peculiarities may to a great extent be described as psychical archaisms… The part of a person’s psychical material which has remained infantile and has been repressed as being unserviceable constitutes the core of his unconscious. [Q165, Freud, 1913, p. 184]
  • Whatever we can expect in the way of prophylaxis against neurosis in the individual lies in the hands of a psycho-analytically enlightened education. [Q166, Freud, 1913, p. 190]

Standard Edition, Volume 14. On the History of the Psycho-Analytic Movement, Papers on Metapsychology and Other Words. 1914-1916.


  • The theory of repression is the corner-stone on which the whole structure of psycho-analysis rests. [Q166b, Freud, 1913, p. 16]
  • If anyone sought to place the theory of repression and resistance among the premises instead of the findings of psycho-analysis, I should oppose him most emphatically. Such premises of a general psychological and biological nature do exist, and it would be useful to consider them on some occasion; but the theory of repression is a product of psycho-analytic work, a theoretical inference legitimately drawn from innumerable observations. [Q167, Freud, 1914, p. 17]
  • A pressing motive for occupying ourselves with the conception of primary and normal narcissism arose when the attempt was made to subsume what we know of dementia praecox (Kraepelin) or schizophrenia (Bleuler) under the hypothesis of libido theory. Patients of this kind… display two fundamental characteristics: megalomania and diversion of interest from the external world – from people and things. [Q168, Freud, 1914a, p. 74]
  • With the [paranoid schizophrenic], he seems to have withdrawn his libido from people and things in the external world, without replacing them by others in fantasy. When we does so replace them, the process seems to be a secondary one and to be part of an attempt at recovery, designed to lead the libido back to objects. [Q169, Freud, 1914a, p. 74b]
  • The question arises: What happens to the libido which has been withdrawn from external objects in schizophrenia? The megalomania characteristic of these states points the way. This megalomania has no doubt come into being at the expense of object-libido. The libido that has been withdrawn from the external world has been directed to the ego and thus gives rise to an attitude which may be called narcissism. But the megalomania itself is no new creation; on the contrary, it is, as we know, a magnification and plainer manifestation of a condition which has already existed previously This leads us to look upon the narcissism which arises through the drawing in of object-activity as a secondary one, superimposed upon a primary narcissism that is obscured by a number of different influences. [Q170, Freud, 1914b, p. 75]
  • This extension of the libido theory – in my opinion, a legitimate one – receives reinforcement from a third quarter, namely, from our observations and views on the mental life of children and primitive peoples. In the latter we find characteristics which, if they occurred singly, might be put down to megalomania: an over-estimation of the power of their wishes and mental acts, the omnipotence of thoughts, a belief in the thaumaturgic [magical] force of words, and a technique for dealing with the external world – ‘magic’ – which appears to a logical application of these grandiose premises. [Q171, Freud, 1914b, p. 75b]
  • In children of today, whose development is much more obscure to us, we expect to find an exactly analogous attitude towards the external world. Thus we form the idea of there being an original libidinal activation of the ego, from which some is later given off to objects, but which fundamentally persists and is related to the object-energy much as the body of an amoeba is related to the pseudopodia which it puts out. [Q172, Freud, 1914b, p. 75c]
  • We can see broadly speaking, an antithesis between ego-libido and object-libido. The more of the one is employed, the more of the other becomes depleted. [Q173, Freud, 1914b, p. 76]
  • A unity comparable to the ego cannot exist from the start; the ego has to be developed. [Q174, Freud, 1914b, p. 77]
  • A speculative theory of the relations in question would begin by seeking to obtain a sharply defined concept as its basis. But I am of the opinion that that is just the difference between a speculative theory and a science erected on empirical interpretation. The latter will not envy speculation its privilege of having a smooth, logical unassailable foundation, but will gladly content itself with nebulous, scarcely imaginable basic concepts, which it hopes to apprehend more clearly in the course of its development, or which it is even prepared to replace by others. For these ideas are not the foundation of science, upon which everything else rests: that foundation is observation alone. They are not the bottom but the top of the whole structure, and they can be replaced and discarded without damaging it. The same thing is happening in our day in the science of physics, the basic notions of which as regards matter, centres of force, attraction etc, are scarcely less debatable than the corresponding notions in psycho-analysis. [Q175, Freud, 1914b, p. 77b]
  • We must recollect that all our provisional ideas in psychology will presumably some day be based on an organic substructure. [Q176, Freud, 1914b, p. 78]
  • Just as the transference neuroses have enabled us to trace the libidinal instinctual impulses, so dementia praecox and paranoia will give us insight into the psychology of the ego. [Q177, Freud, 1914b, p. 82]
  • The condition of sleep, too, resembles illness in implying a narcissistic withdrawal o the positions of the libido on to the subject’s own self, or, more precisely, on to the single wish to sleep. The egoism of dreams fits very well in to this context. In both states we have, if nothing else, examples of changes in the distribution of libido that are consequent upon a change in the ego. [Q178, Freud, 1914b, p. 83]
  • The hypochondriac withdraws both interest and libido – the latter specially markedly – from the objects of the external world and concentrates both of them upon the organ that is engaging attention. [Q179, Freud, 1914b, p. 83]
  • The path from introversion [i.e., withdrawal] to regression [e.g., hallucinosis] is to be linked to a damming-up of object-libido. [Q180, Freud, 1914b, 84]
  • At this point, our curiosity will of course raise the question why this damming-up of libido in the ego should have to be experienced as unpleasurable. I shall content myself with the answer that unpleasure is always the expression of a higher degree of tension. [Q181, Freud, 1914b, p. 85]
  • Here we might venture to touch on the question of what makes it necessary at all for our mental life to pass beyond the limits of narcissism and to attach the libido to objects. The answer which would follow from our line of thought would once more be that this necessity arises when the filling of the ego with libido exceeds a certain amount. A strong egoism is a protection against falling ill, but in the last resort we must begin to love in order not to fall ill, and we are bound to fall ill if, in consequence of frustration, we are unable to love. [Q182, Freud, 1914b, p. 85b]
  • In [paranoid schizophrenia] megalomania allows of a similar internal working over of libido which has returned to the ego; perhaps it is only when the megalomania fails that the damming up of libido in the ego becomes pathogenic and starts the process of recovery which gives us the impression of being a disease. [Q183, Freud, 1914b, p. 86]
  • The difference between paranoid schizophrenia and the transference neuroses appears to me to lie in the circumstance that, in the former, the libido that is liberated by frustration does not remain attached to objects in fantasy, but withdraws on to the ego. Megalomania would accordingly correspond to the psychical mastering of the latter amount of libido and would thus be the counterpart of the introversion on to fantasies that is found in the transference neuroses. [Q184, Freud, 1914b, p. 86b]
  • Repression we have said proceeds from the ego, we might say with greater precision that it proceeds from the self-respect of the ego. [Q185, Freud, 1914b, p. 93]
  • For the ego, the formation of an ideal would be the conditioning factor of repression. [Q186, Freud, 1914b, p. 94]
  • The ego ideal is now the target of the self-love which was once enjoyed in childhood by the actual ego. The subject’s narcissism makes its appearance displaced on to this new ideal ego, which, like the infantile ego, finds itself possessed of every perfection that is of value. As always where the libido is concerned, man has here shown himself to be incapable of giving up a satisfaction he had once enjoyed. He is not willing to forgo the narcissistic perfection of his childhood; and when as he grows up, he is disturbed by the admonitions of others and by the awakening of his own critical judgment, so that he can no longer retain that perfection, he seeks to recover it in the new form of an ideal. What he projects before him as his ideal is the substitute for the lost narcissism of his childhood in which he was his own ideal. [Q187, Freud, 1914b, p. 94b]
  • It would not surprise us if we were to find a special psychical agency which performs the task of seeing that narcissistic satisfaction from the ego ideal is ensured and which, with this end in view, constantly watches the actual ego and measures it by that ideal. If such an agency does exist, we cannot possible come upon it as a discovery – we can only recognise it; for we may reflect that what we call ‘conscience’ has the required characteristics. Recognition of this agency enables us to understand the so-called ‘delusions of being noticed’ or more correctly, of being watched, which are such striking symptoms in the paranoid diseases. [Q188, Freud, 1914b, p. 95]
  • Paranoid patients complain that all their thoughts are known and their actions watched and supervised; they are informed of the functioning of this agency by voices which characteristically speak to them in the third person ‘Now she’s thinking of that again’, ‘now he’s going out’. This complaint is justified; it describes the truth. A power of this kind, watching, discovering and criticising all our intentions, does really exist. Indeed, it exists in everyone of us in normal life. [Q189, Freud, 1914b, p. 95]
  • For what prompted the subject to form an ego ideal, on whose behalf his conscience acts as a watchman, arose from the critical influence of his parents (conveyed to him by the medium of the voice) to whom were added, as time went on, those who trained and taught him and the innumerable and indefinable host of all the other people in his environment – his fellow men – and public opinion. [Q190, Freud, 1914b, p. 96]
  • The institution of conscience was at bottom an embodiment, first of parental criticism and subsequently of that of society – a process which is repeated in what takes place when a tendency towards repression develops out of a prohibition of obstacle that came in the first from without. [Q191, Freud, 1914b, p. 96]
  • The voices, as well as the undefined multitude, are brought into the foreground again by the disease [schizophrenia], and so the evolution of conscience is reproduced regressively. But the revolt against this ‘censoring agency’ arises out of the subject’s desire (in accordance with the fundamental character of his illness) to liberate himself from all these influences… His conscience then confronts him in a regressive form as a hostile influence from without. [Q192, Freud, 1914b, p. 96b]
  • Thus the activity of the mind which has taken over the function of conscience has also placed itself at the service of internal research, which furnishes philosophy with the material fro its intellectual operations. This may have some bearing on the characteristic tendency of paranoics to construct speculative systems. [Q193, Freud, 1914b, p. 96c]
  • It is easy to observe that libidinal object-investment does not raise self-regard. The effect of dependence upon the loved object is to lower that feeling: a person in love is humble. A person who loves has, so to speak, forfeited a part of his narcissism, and it can only be replaced by his being loved. [Q194, Freud, 1914b, p. 98]
  • It is also true that a real happy love corresponds to the primal condition in which object-libido and ego-libido [object and subject] cannot be distinguished. [Q195, Freud, 1914b, p. 100]
  • The development of the ego consists in a departure from primary narcissism and gives rise to a vigorous attempt to recover that state. This departure is brought about by means of the displacement of libido on to an ego ideal imposed from without; and satisfaction is brought about from fulfilling this ideal. At the same time the ego has sent out the libidinal object-investments. It becomes impoverished in favour of these investments, just as it does in favour of the ego ideal, and it enriches itself once more from its satisfactions in respect of the object, just as it does by fulfilling its ideal. One part of the self-regard is primary – the residue of infantile narcissism; another part arises out of the omnipotence which is corroborated by experience (the fulfilment of the ego ideal), whilst a third part proceeds from the satisfaction of object-libido. [Q196, Freud, 1914b, p. 100]
  • We have often heard it maintained that sciences should be built up on clear and sharply defined basic concepts. In actual fact no science, not even the most exact, beings with such definitions. The true beginning of scientific activity consists rather is describing phenomena and then in proceeding to group, classify and correlate them. [Q197, Freud, 1915, p. 117]
  • We thus arrive at the essential nature of drives in the first place by considering their main characteristics – their origin in sources of stimulation within the organism and their appearance as a constant force. [Q198, Freud, 1915, p. 119]
  • The nervous system is an apparatus which has the function of getting rid of stimuli that reach it, or of reducing them to the lowest possible level’ or which, if it were feasible, would maintain itself in an altogether unstimulated condition. [Q199, Freud, 1915, p. 120]
  • Let us for the present not take exception to the indefiniteness of this idea and let us assign to the nervous system the task – speaking in general terms – of mastering stimuli. [Q200, Freud, 1915, p. 120]
  • If now we apply ourselves to considering mental life from a biological point of view, a ‘drive’ appears to us as a concept on the frontier between the mental and the somatic, the psychical representation of the stimuli originating from within the organism and reaching the mind, as a measure of the demand made upon the mind fro work in consequence of its connection with the body. [Q201, Freud, 1915, p. 122]
  • The object of a drive is the thing in regard to which or through which the instinct is able to achieve its aim. [Q202, Freud, 1915, p. 122b]
  • Marked instinctual ambivalence in a human being living at the present day may be regarded as an archaic inheritance, for we have reason to suppose that the part played in instinctual life by the active impulses in their unmodified form was greater in primaeval times than it is on average today. [Q203, Freud, 1915, p. 131]
  • The antithesis active-passive must not be confused with the antithesis ego-subject external world-object. The relation of the ego to the external world is passive in so far as it receives stimuli from it and active when it reacts to these. [Q204, Freud, 1915, p. 134]
  • Hate, as a relation to objects, is older than love. It derives from the narcissistic ego’s primordial repudiation of the external world. [Q205, Freud, 1915, p. 139]
  • Under certain conditions, which we shall presently investigate more closely, the impulse then passes into a state of ‘repression’. If what was in question was the operation of an external stimulus, the appropriate method to adopt would obviously be flight; with a drive, flight is of no avail, for the ego cannot escape from itself. At some later period, rejection based on judgment (condemnation) will be found to be a good method to adopt against an instinctual impulse. Repression is a preliminary stage of condemnation, something between flight and condemnation; it is a concept which could not have been formulated before the time of psycho-analytic studies. [Q205, Freud, 1915, p. 146]
  • The essence of repression lies simply in turning something away, and keeping it at a distance, from the conscious. [Q206, Freud, 1915, p. 147]
  • We have reason to assume that there is a primal repression, a first phase of repression, which consists in the psychical (ideational) representative of the drive being denied entrance into the conscious. [Q207, Freud, 1915, p. 148]
  • This deceptive strength of drive is the result of an uninhibited development in fantasy and of the damming-up consequent on frustrated satisfaction. The fact that this last result is bound up with repression points the direction in which the true significance of repression has to be looked for. [Q208, Freud, 1915, p. 149]
  • The process of repression is not to be regarded as event which takes place once, the results of which are permanent, as when some living thing has been killed and from that time onward is dead; repression demands a persistent expenditure of force, and if this were to cease the success of the repression would be jeopardised, so that a fresh act of repression would be necessary. We may suppose that the repressed exercises a continuous pressure in the direction of the conscious, so that this pressure must be balanced by an unceasing counter-pressure. Thus the maintenance of a repression involves an uninterrupted expenditure of force, while its removal results in a saving from an economic point of view. [Q209, Freud, 1915, p. 151]
  • The mechanisms of repression have at least this one thing in common: a withdrawal of the investment of energy. [Q210, Freud, 1915, p. 155]
  • The vanished affect comes back in its transformed shape as social anxiety, moral anxiety and unlimited self-reproaches. [Q211, Freud, 1915, p. 157]
  • We have learnt from psycho-analysis that the essence of the process of repression lies, not in putting an end to, in annihilating, the idea which represents a drive but in preventing it from becoming conscious. [Q212, Freud, 1915b, p. 166]
  • Everything that is repressed must remain unconscious; but let us state at the very outset that the repressed does not cover everything that is unconscious. The unconscious has the wider compass: the repressed is a part of the unconscious. [Q213, Freud, 1915b, p. 166b]
  • How are we to arrive at a knowledge of the unconscious? It is of course only as something conscious that we know of it, after it has undergone transformation or translation into something conscious. [Q214, Freud, 1915b, p. 166c]
  • When all our latent memories are taken into consideration it becomes incomprehensible how the existence of the unconscious can be denied. [Q215, Freud, 1915b, p. 167]
  • Incidentally, even before the time of psycho-analysis, hypnotic experiments, and especially post-hypnotic suggestion, had tangibly demonstrated the existence and mode of operation of the mental unconscious. [Q216, Freud, 1915b, p. 169]
  • Without any special reflection we attribute to everyone else our own constitution and therefore our consciousness as well, and that this identification is a sine qua non of our understanding. This inference (or this identification) was formerly extended by the ego to other human beings, to animals, plants, inanimate objects and to the world at large, and proved serviceable so long as their similarity to the individual ego was overwhelmingly great; but it became more untrustworthy in proportion as the difference between the ego and these others widened. [Q217, Freud, 1915b, p. 169b]
  • This process of inference, when applied to oneself in spite of internal opposition, does not, however, lead to the disclosure of an unconscious; it leads logically to the assumption of another, second consciousness which is united in oneself with the consciousness one knows. [Q218, Freud, 1915b, p. 170]
  • In psychoanalysis there is no choice for us but to assert that mental processes are in themselves unconscious, and to liken the perception of them by means of consciousness to the perception of the external world by means of the sense organs. [Q219, Freud, 1915b, p. 171]
  • The unconscious comprises, on the one hand, acts which are merely latent, temporarily unconscious, but which differ in no other respect from conscious ones and, on the other hand, processes such as repressed ones, which if they were to become conscious would be bound to stand out in the crudest contrast to the rest of the conscious processes. [Q220, Freud, 1915b, p. 172]
  • We cannot escape the ambiguity of using the words ‘conscious’ and ‘unconscious’, sometimes in a descriptive and sometimes in a systematic sense, in which the latter signify inclusion in particular systems and possessions of certain characteristics. [Q221, Freud, 1915b, p. 172b]
  • Or are we rather to be believe that the transposition consists in a change in the state of the idea, a change involving the same material and occurring in the same locality? This question may appear abstruse, but it must be raised if we wish to form a more definite conception of the psychical topography, of the dimension of depth in the mind. It is a difficult one because it goes beyond pure psychology and touches on the relations pf the mental apparatus to anatomy. We know that in the very roughest sense such relations exist. Research has given irrefutable proof that mental activity is bound up with the function of the brain as it is with no other organ. [Q222, Freud, 1915b, p. 174]
  • There is a hiatus here which at present cannot be filled, nor is it one of the tasks of psychology to fill it. Our psychical topography has for the present nothing to do with anatomy; it has reference not to anatomical localities but to regions in the mental apparatus wherever they may be situated in the body. [Q223, Freud, 1915b, p. 175]
  • Strictly speaking, then, and although no fault can be found with the linguistic usage, there are no unconscious affects as there are unconscious ideas. But there may very well be in the system Ucs, affective structures which, like others, become conscious. The whole difference arises from the fact that ideas are activations/investments – basically of memory-traces, whilst affects and emotions correspond to processes of discharge. [Q224, Freud, 1915b, p. 178]
  • The transition from the system Ucs to the [ego] is not effected through the making of a new registration but through a change in its state, an alteration in its energy/activation. [Q225, Freud, 1915b, p. 180]
  • Besides the dynamic and the topographical points of view, we have adopted the economic This endeavours to follow out the vicissitudes of amounts of excitation and to arrive at least at some relative estimate of their magnitude. [Q226, Freud, 1915b, p. 181]
  • The distinction we have made between the two psychical systems receives fresh significance when we observe that processes in the one system, the Ucs, show characteristics which are not met with again the system immediately above it [the ego]. [Q227, Freud, 1915b, p. 186]
  • The energetic intensities in the Ucs are much more mobile. By the process of displacement one idea may surrender to another its whole quote of energy; by the process of condensation it may appropriate the whole energy of several other ideas. I have proposed to regard these two processes as distinguishing marks of the so-called primary psychical process. In the [ego], the secondary process is dominant. When a primary process is allowed to take its course in connection with elements belonging to the ego, it appears comic and excites laughter. [Q228, Freud, 1915b, p. 186b]
  • The processes of the system Ucs are timeless; i.e., they are not ordered temporally, are not altered by the passage of time; they have no reference to time at all. Reference to time is bound up, once again, with the work of the [ego]. [Q229, Freud, 1915b, p. 187]
  • To sum up: exemption from mutual contradiction [e.g., opposite emotions existing together], timelessness and replacement of external by psychical reality – these are the characteristics which we may expect to find in processes belonging to the system Ucs. [Q230, Freud, 1915b, p. 187b]
  • Unconscious processes only become cognizable by us under conditions of dreaming and of neurosis – that is to say, when the process of the higher [ego] system are set back to an earlier stage… In themselves they cannot be cognized, indeed are even incapable of carrying on their existence; for the system Ucs is at a very early moment overlaid by the ego which has taken over access to consciousness and to motility. [Q231, Freud, 1915b, p. 188]
  • The full significance of the characteristics of the system Ucs described above could only be appreciated by us if we were to contrast them with those of the system Ucs. [Q232, Freud, 1915b, p. 188b]
  • Breuer [assumed] the existence of two different states of energy in mental life: one in which the energy is tonically ‘bound’ and the other is which it is freely mobile and presses towards discharge. In my opinion this distinction represents the deepest insight we have gained up to the present into the nature of nervous energy. [Q233, Freud, 1915b, p. 188b]
  • Further, it devolves upon the [ego] to make communication possible between the different ideational contents so that they can influence one another, to give them an order in time, and to set up a censorship or several censorships; ‘reality-testing’ too, and the reality-principle are its province. Conscious memory, moreover, seems to depend on the [ego]. This should clearly be distinguished from the memory-traces in which the experiences of the Ucs are fixed. [Q234, Freud, 1915b, p. 189]
  • We are describing the state of affairs as it appears in the adult human being, in whom the system Ucs operates, strictly speaking, only as a preliminary stage of the higher organisation. [Q235, Freud, 1915b, p. 189b]
  • Moreover, in human beings we must be prepared to find possible pathological conditions under which the two systems alter, or even exchange, both their content and their characteristics. [Q236, Freud, 1915b, p. 189c]
  • It would nevertheless be wrong to imagine that the Ucs remains at rest while the whole work of the mind is performed by the [ego] – that the Ucs is something finished with, a vestigial organ, a residuum from the process of development. It is wrong also to suppose that communication between the two systems is confined to the act of repression, with the [ego] casting everything that seems disturbing to it into the abyss of the Ucs. On the contrary, the Ucs is alive and capable of development and maintains a number of other relations with the [ego] amongst them that of cooperation. [Q237, Freud, 1915b, p. 190]
  • The act of becoming conscious is dependent on the attention of the [ego] being turned in certain directions. [Q238, Freud, 1915b, p. 192]
  • The more we seek to win our way to a metapsychological [i.e., a mechanistic] view of mental life, the more we must learn to emancipate ourselves from the importance of the symptom of ‘being conscious’. [Q239, Freud, 1915b, p. 193]
  • The existence of the censorship between the [ego] and [consciousness] teaches us that becoming conscious is no mere act of perception, but is probably also a hyperactivation,, a further advance in the psychical organisation. [Q240, Freud, 1915b, p. 194]
  • The unconscious is also affected by experiences originating from external perception. Normally all the paths from perception to the Ucs remain open and only those leading on from the Ucs are subject to blocking by repression. [Q241, Freud, 1915b, p. 194b]
  • The content of the Ucs may be compared with an aboriginal population in the mid. If inherited mental formations exist in the human being – something analogous to instinct in animals – these constitute the nucleus of the Ucs. Later there is added to them what is discarded during childhood development as unserviceable, and this need not differ in its nature from what is inherited. A sharp and final division between the content of the two systems does not, as a rule, take place till puberty. [Q242, Freud, 1915b, p. 195]
  • We have tried to base our characterisation of Kraepelin’s dementia praecox (Bleuler’s schizophrenia) on its position with reference to the antithesis between ego and object. [Q243, Freud, 1915b, p. 196]


  • In the case of schizophrenia, on the other hand, we have been driven to the assumption that after the process of repression the libido that has been withdrawn does not seek a new object but retreats into the ego; that is to say, that here the object-investments are given up and a primitive objectless condition of narcissism is re-established. The incapacity of these patients for transference (so far as the pathological process extends), their consequent inaccessibility to therapeutic efforts, their characteristic repudiation of the external world, the appearance of signs of a hyper-activation of their own ego, the final outcome in complete apathy – all these clinical features seem to agree excellently with the assumption that their object-investments have been given up. [Q244, Freud, 1915b, p. 197]
  • As regard the relation of the two psychical systems to each other, all observers have been struck by the fact in schizophrenia a great deal is expressed as being conscious which in the transference neuroses can only be shown to be present in the Ucs by psycho-analysis. [Q245, Freud, 1915b, p. 197b]
  • In schizophrenia we observe – especially in the initial stages, which are so instructive – a number of changes in speech, some of which deserve to be regarded from a particular point of view. The patient often devotes peculiar care to his way of expressing himself, which becomes stilted and precious. The construction of his sentences undergoes a peculiar disorganisation. [Q246, Freud, 1015b, p. 197c]
  • In schizophrenia words are subjected to the same process as that which makes the dream images out of the latent dream-thoughts – to what we have called the primary psychical process. They undergo condensation and by means of displacement transfer their energy to one another in their entirety. The process may go so far that a single word, if it specially suitable in account of its numerous connections, takes over the representation of a while train of thought. [Q247, Freud, 1915, p. 199]
  • If now we put this finding alongside the hypothesis that in schizophrenia object-investments are given up, we shall be obliged to modify the hypothesis by adding that the investment of the word-presentation of objects is retained. What we have permissibly called the conscious presentation of the object can now be split up into the presentation of the word and the presentation of the thing; the latter consists in the activation, if not of the direct memory-images of the thing, at least of remoter memory-traces derived from these. [Q248, Freud, 1915b, p. 202]
  • The conscious presentation comprises the presentation of the thing plus the presentation of the word belonging to it, while the unconscious presentation is the presentation of the thing alone. The system Ucs contains the thing-activations of the objects, the first and true object-activations; the [ego] comes about by this thing presentation being hyper-activated through being linked with word-presentations corresponding to it. It is these hyperactivations, we may suppose, that bring about a higher psychical organisation and make it possible for the primary process to be succeeded by the secondary process which is dominant in the ego. Now too, we are in a position to state precisely what it is that repression denies to the rejected presentation in the transference neuroses: what it denies to the presentation is translation into words, which shall remain attached to the object. A presentation which is not put into words, or a psychical act which is not hyperactivated, remains therefore in the Ucs in a state of repression. [Q249, Freud, 1915b, p. 202b]
  • Probably, however, thought proceeds in systems so far remote from the original perceptual residues that they have no longer retained anything of the qualities of those residues, and, in order to become conscious, need to be reinforced by new qualities. Moreover, by being linked with words, activations can be provided with quality, even when they present only relations between presentations of objects and are thus unable to derive any quality from perceptions. Such relations, which become comprehensible only through words, form a major part of out thought processes. [Q250, Freud, 1915b, p. 202c]
  • As we can see, being linked with word-presentation is not yet the same thing as becoming conscious, but only makes it possible to become so; it is therefore characteristic of the [ego] and of that system alone. [Q251, Freud, 1915b, p. 202-203]
  • The ego’s attempt at flight, which expresses itself in the withdrawal of the conscious activation, nevertheless remains a factor common to [transference and narcissistic neuroses]. The most superficial reflection shows us how much more radically and profoundly this attempt at flight, this flight of the ego, is put into operation is the narcissistic neuroses. [Q252, Freud, 1915b, p. 203]
  • If in schizophrenia, this flight consists in withdrawal of instinctual energy from the points which represent the unconscious presentation of the object, it may seems strange that the part of the presentation of this object which belongs to the [ego] namely – word presentation corresponding to it – should, on the contrary receive a major activation… It turns out that the activation of the word presentation is not part of the act of repression but represents the first of the attempts at recovery or cure which so conspicuously dominate the clinical picture of schizophrenia. [Q253, Freud, 1915b, p. 203-204]
  • These endeavours are directed towards regaining the lost object and it may well be that to achieve this purpose they set off on a path that leads to the object via the verbal part of it, but then find themselves obliged to be content with words instead of things. It is a general truth that our mental activity moves in two opposite directions: either it starts from the instincts and passes through the system Ucs to conscious thought-activity; or, beginning with an instigation from outside, it passes through the [ego] till; it reaches the Ucs activations of the ego and objects. This second path must in spite of the repression which has taken place, remain traversable, and it lies open to some extent to the endeavours make by the neuroses to regain its objects. When we think in abstractions there is a danger that we may neglect the relations of words to unconscious thing-presentations. [Q253, Freud, 1915b, p. 204b]
  • We learn to speak the language of other people by endeavouring to make the sound-image produced by ourselves as like as possible to the one which gave rise to our speech innervation. [Q254, Freud, 1891, p. 211]
  • A dream is, therefore, among other things, a projection: an externalisation of an internal process. [Q255, Freud, 1917, p. 223]
  • The essential difference between the dream-work and schizophrenia becomes clear. In the latter, what becomes the subject of modification by the primary process are the words themselves…; in dreams, what are subject to modification are not the words but the thing-presentations to which the words have been taken back. In dreams there is topographical regression [i.e., the system Ucs and the primary process becoming dominant]; in schizophrenia there is not. In dreams there is free communication between the [ego] word-activations and the Ucs thing-activations, while it is characteristic of schizophrenia that this communication is cut off. [Q256, Freud, 1917, p. 229]
  • Hallucination consists in an activation of the perceptual system which however, is not effected – as normally – from without but from within. [Q257, Freud, 1917, p. 232]
  • This function of orienting the individual in the world by discrimination between what is internal and what is external must now after detailed dissection of the mental apparatus, be ascribed to the perceptual system alone. This system must have at its disposal a motor innervation which determines whether the perception can be made to disappear or whether it proves resistant. Reality-testing need be nothing more than this contrivance. [Q258, Freud, 1917, p. 233]
  • We shall place reality-testing among the major institutions of the ego, alongside the censorships which have come to recognise between the psychical systems. [Q259, Freud, 1917, p. 233b]
  • With this turning away from reality, reality-testing is got rid of, the wishful fantasies are able to press forward into the system and they are there regarded as a better reality. [Q260, Freud, 1917, p. 233c]
  • Amentia [hallucinatory delirium] presents the interesting spectacle of a breach between the ego and one of its organs [the hippocampus?] one which had perhaps been its most faithful servant and had been bound up with it most intimately. [Q261, Freud, 1917, p. 233d]
  • As regards the hallucinatory psychosis of dementia praecox, we shall infer from our discussion that that psychosis cannot be among the initial symptoms of the affection. It becomes possible only when the patient’s ego is so far disintegrated that reality-testing no longer stands in its way. [Q262, Freud, 1917, p. 234]
  • In mourning, reality-testing has shown that the loved object no longer exists and it proceeds to demand that all libido shall be withdrawn from its attachments to that object… Opposition to this can be so intense that a turning away from reality takes place and a clinging to the object through the medium of a hallucinatory wishful psychosis. [Q263, Freud, 1917b, p. 244]
  • Melancholia is in some way related to an object-loss which is withdrawn from consciousness, in contradistinction to mourning, in which there is nothing about the loss that is unconscious. [Q264, Freud, 1917, p. 245]
  • In mourning we found that the inhibition and loss of interest are fully accounted for by the work of mourning in which the ego is absorbed. In melancholia, the unknown loss will result in a similar internal work and will therefore be responsible for the melancholic inhibition. [Q265, Freud, 1917b, p. 245b]
  • We see how in hum one part of the ego sets itself over against the other, judges it critically and as it were takes it as its object. Our suspicion that the critical agency which is here split off from the ego might also show its independence in other circumstances will be confirmed by every further observation. We shall really find grounds for distinguishing this agency from the rest of the ego. What we are here becoming acquainted with is the agency commonly called ‘conscience’; we shall count it, along with the censorship of consciousness and reality-testing, among the major institutions of the ego, and we shall come upon evidence to show that it can become diseased in its own account. [Q266, Freud, 1917b, p. 247]
  • There is no difficulty in reconstructing [the] process of [melancholia]. An object-choice, an attachment of the libido to a particular person, had at one time existed; then, owing to a real slight or disappointment coming from this loved person, the object-relationship was shattered… But the free libido was not displaced on to another object; it was withdrawn into the ego… Thus the shadow of the object fell upon the ego and the latter could henceforth be judged by a special agency, as though it were the forsaken object… One or two things may be directly inferred with regards to the preconditions and effects of a process such as this. On the one hand, a strong fixation to the loved object must have been present; on the other hand, in contradiction to this, the object-[investment] must have had little power of resistance… This contradiction seems to imply that the object-choice had been effected on a narcissistic basis, so that the object-[investment], when obstacles [came] in its way, [could] regress to narcissism. [Q267, Freud, 1917b, p. 249]
  • Recovery in a case of schizophrenia; it represents, of course, a regression from one type of object choice to original narcissism. We have elsewhere shown that identification is a preliminary stage of object-choice, that it is the first way – and one that is expressed in an ambivalent fashion – in which the ego picks out an object. The ego wants to incorporate this object into itself, and, in accordance with the oral or cannibalistic phase of libidinal development in which it is, it wants to do so by devouring it. [Q268, Freud, 1917b, p. 250]
  • Melancholia therefore borrows some of its features from mourning and the others from the process of regression from narcissistic object-choice to narcissism. [Q269, Freud, 1917b, p. 250]
  • The loss of a love-object is an excellent opportunity for the ambivalence in love-relationships to make itself effective and come into the open. Where there is a disposition to obsessional neurosis the conflict die to ambivalence gives a pathological cast to mourning and forces it to express itself in the form of self-reproaches to the effect that the mourner himself is to blame for the loss of the loved object i.e., he has willed it. [Q270, Freud, 1917b, p. 251]
  • If the love for the object – a love which cannot be given up though the object itself is given up –takes refuge in narcissistic identification, then the hate comes into operation on this substitutive object, abusing it, debasing it, making it suffer and deriving sadistic satisfaction from its suffering. The self-tormenting in melancholia which is without doubt enjoyable signifies just like the corresponding phenomenon in obsessional neurosis a satisfaction of trends of sadism and hate which relate to an object and which have been turned round upon the subject’s own self. [Q271, Freud, 1917b, p. 251b]
  • In taking revenge on the original object and in tormenting their loved one through their illness, having resorted to it in order to avoid the need to express to express their hostility to him openly. [Q272, Freud, 1917b, p. 251c]
  • It is this sadism alone that solves the riddle of the tendency to suicide which make melancholia so interesting and so dangerous. So immense is the ego’s self-love, which we have come to recognise as the primal state rom which instinctual life proceeds, and so vast is the amount of narcissistic libido which we see liberated in the fear that emerges at a threat to life, that we cannot conceive how that ego can consent to its own destruction. We have long known, it is true, that no neurotic harbours thoughts of suicide which he has not turned back upon himself from murderous impulses against others. [Q273, Freud, 1917b, 252]
  • In the two opposed situations of being most intensely in love and of suicide the ego is overwhelmed by the object though in totally different ways. [Q274, Freud, 1917b, p. 252b]
  • The manic subject plainly demonstrates his liberation from the object which was the cause of his suffering by seeking like a ravenously hungry man for new object-activations. [Q275, Freud, 1917b, p. 255]
  • Each single one of the memories and situations of expectancy which demonstrate the libido’s attachment to the lost object is met by the verdict of reality that the object no longer exists; and the ego, confronted as it were with the question whether it shall share this fate,, is persuaded by the sum of the narcissistic satisfactions it derives from being alive to sever its attachment to the object that has been abolished. We may perhaps suppose that this work of severance is so slow and gradual that by the time it has been finished the expenditure of energy necessary for it has dissipated. [Q276, Freud, 1917b, p. 255b]
  • The accumulation of energy which is at first bound and then, after the work of melancholia is finished, becomes free and makes mania possible must be linked with regression of the libido to narcissism. The conflict within the ego, which melancholia substitutes for the struggle over the object, must act like a painful wound which calls for an extraordinarily high inhibitory force [repression]. [Q277, Freud, 1917b, p. 258]
  • When a village grows into a town or child into a man, the village and the child become lost in the town and the man. [Q278, Freud, 1915c, p. 285]
  • The primitive mind is, in the fullest meaning of the word, imperishable. [Q279, Freud, 1915c, p. 286]
  • The man of prehistoric times survives unchanged in our unconscious. Our unconscious then, does not believe in its own death; it behaves as if it were immortal. [Q280, Freud, 1915c, p. 296]

Standard Edition, Volume 15. Introductory Lectures on Psycho-Analysis. Parts I & II. 1915-1916.

  • The prehistory into which the dreamwork leads us back is of two kinds – on the one hand, into the individual’s prehistory, his childhood and on the other, in so far as each individual somehow recapitulates in an abbreviated form the entire development of the human race, into phylogenic history too… It seems to me that symbolic connections, which the individual has never acquired by learning may justly claim to be regard as a phylogenetic heritage. [Q281, Freud, 1916, p. 199]
  • The regression of the dreamwork is not only a formal one but also a material one. It not only translates our thoughts into a primitive form of expression; but it also revives the characteristics of our primitive mental life. [Q282, Freud, 1916, p. 211]

Standard Edition, Volume 16. Introductory Lectures on Psychoanalysis. Part III. 1916-1917.


  • We can say that the mental apparatus serves the purpose of mastering and disposing of the amounts of stimulus and sums of excitation that impinge on it from outside and inside. [Q283, Freud, 1917c, p. 356-357]
  • A nature reserve preserves its original state which everywhere else has to our regret been sacrificed to necessity. Everything, including what is useless and even what is noxious, can grow and proliferate there as it pleases. The mental realm of fantasy is just such reservation withdrawn from the reality principle… The best known productions of fantasy are the day-dreams [Q284, Freud, 1917c, p. 372]
  • The ultimate aim of mental activity, which may be described qualitatively as an endeavour to obtain pleasure and avoid unpleasure, emerges, looked at from the economic point of view, as the task of mastering the amounts of excitation (mass of stimuli) operating in the mental apparatus and of keeping down their accumulation which creates unpleasure. [Q285, Freud, 1917c, p. 375]
  • Repression corresponds to an attempt at flight by the ego from libido which is felt as danger. [Q286, Freud, 1917c, p. 410]
  • I have already spoken to you of the [inhibitory action] which is employed by the ego in the process of repression which must be permanently maintained in order that the repression may have stability. [Q287, Freud, 1917c, p. 411]
  • The question then arose of what happened to the libido of dementia praecox patients which was turned away from objects. Abraham did not hesitate to give the answer: it is turned back on to the ego and this reflexive turning-back is the source of the megalomania in dementia praecox. [Q288, Freud, 1917c, p. 415]
  • We pictured the relation of ego-libido to object-libido in a way which I can make plain to you by an analogy from zoology. Think of those simplest of living organisms [the amoebas] which consist of a little differentiated globule of protoplasmic substance. They put out protrusions, known as pseudopodia, into which they cause the substance of their body to flow over. They are able, however, to withdraw the protrusions once more and form themselves again into a globule. We compare the putting out of these protrusions, then, to the emission of libido on to objects while the main mass of libido can remain in the ego; and we suppose that in normal circumstances ego-libido can be transformed unhindered into object libido and that this can once more be taken back into the ego. [Q289, Freud, 1917c, p. 416]
  • In a sleeper the primal state of distribution of the libido is restored – total narcissism, in which libido and ego-interest, still united and indistinguishable, dwell in the self-sufficing ego. [Q290, Freud, 1917c, p. 417]
  • It is possible to be absolutely egoistic and yet maintain powerful object-activations, in so far as the libidinal satisfaction in relation to the object froms part of the ego’s needs. In that case, egoism will see to it that striving for the object involves no damage to the ego. It is possible to be egoistic and at the same time to be excessively narcissistic – that is to say, to have very little need for an object. [Q291, Freud, 1917c, p. 417c]
  • When a particular, very energetic process forces a withdrawal of libido from objects. Here the libido that has become narcissistic cannot find its way back to objects and this interference with the libido’s mobility certainly becomes pathogenic. It seems that an accumulation of narcissistic libido beyond a certain amount is not tolerated. We may even imagine that it was for that very reason that object-activations originally came about, that the ego was obliged to send out its libido so as not to fall ill as a result of its being dammed up. [Q292, Freud, 1917c, p. 421]
  • The clinical picture of dementia praecox (which incidentally, is very changeable) is not determined exclusively by the symptoms arising the forcing away of the libido from objects and its accumulation in the ego as narcissistic libido. A large part, rather, is played by other phenomena, which are derived from efforts of the libido to attain objects once more and which thus correspond to an attempt at restitution or recovery. These latter symptoms are indeed the more striking and noisy… It seems as though in dementia praecox the libido, in its efforts once more to reach objects (that is, the presentation of objects), does in fact snatch hold of something of them, but, as it were, only their shadows – I mean the word-presentations belonging to them. [Q293, Freud, 1917c, p. 422]
  • We have discovered that the self-reproaches, with which these melancholic patients torment themselves in the most merciless fashion, in fact apply to another person, the sexual object which they have lost or which has become valueless to them through its own fault. From this we can conclude that the melancholic has, it is true, withdrawn his libido from the object, but that, by a process which we must call ‘narcissistic identification’, the object has been set-up in the ego itself, has been, as it were projected into the ego… The subject’s own ego is then treated like the object that has abandoned, and it is subjected to all the acts of aggression and expressions of vengefulness which have been aimed at the object. A melancholic’s propensity to suicide is also made more intelligible if we consider that the patient’s embitterment strikes with a single blow at his own ego and at the loved and hated object. [Q294, Freud, 1917c, p. 427]
  • From the analysis of delusions of observation we have drawn the conclusion that there actually exists in the ego an agency which unceasingly observes, criticises and compares and in that way sets itself over against the other part of the ego. [Q295, Freud, 1917c, p. 428]
  • He senses an agency holding sway in his ego which measures his actual ego and each of its activities by an ideal ego that he has created for himself in the course of development… When in delusions of observation it becomes split up, it reveals to us its origins from the influence of parents, educators and social environment – from an identification with some of these model figures. [Q296, Freud, 1917c, p. 429]
  • On the basis of our clinical impressions we maintained that [schizophrenic] patients’ object-activations must have been given up and that their libido must have been transformed into ego-libido. Through this characteristic we distinguished them from the first group of neurotics… This suspicion is now confirmed by their behaviour in our attempts at therapy. They manifest no transference and for that reason are inaccessible to our efforts and cannot be cured by us. [Q297, Freud, 1917c, p. 447]

Standard Edition, Volume 17. An Infantile Neurosis and Other Works. 1917-1919.

  • I will add that all the narcissistic impulses operate from the ego and have their permanent seat in the ego. [Q298, Freud, 1918, p. 111]
  • His extraordinary propensity to ambivalence, and (as a third trait [of the unconscious] in a constitution which deserves the name archaic) his power of maintaining simultaneously the most various and contradictory libidinal activations, all of them functioning side by side. [Q299, Freud, 1918, p. 119]
  • We have been driven to assume that at the beginning of the development of the individual all his libido (all his erotic tendencies, all his capacity for love) is tied to himself – that as we say, it [fills] his own ego. It is only later that, being attached to the satisfaction of the major vital needs, the libido flows over from the ego on to external objects… The condition in which the ego retains the libido is called by us ‘narcissism’, in reference to the Greek legend of the youth Narcissus who was in love with his won reflection. [Q300, Freud, 1917d, p. 139]
  • The ego is a great reservoir from which the libido that is destined for objects flows out and into which it flows back from those objects. Object-libido was at first ego-libido can be transformed back into ego-libido. For complete health it is essential that the libido should not lose this full mobility. As an illustration of this state of things we may think of an amoeba, whose viscous substance puts out pseudopodia, elongations into which the substance of the body extends but which can be retracted at any time so that the form of protoplasmic mass is restored. [Q301, Freud, 1917d, p. 139]
  • For this mind is not a simple thing; on the contrary, it is a hierarchy of superordinated and subordinated agencies, a labyrinth of impulses striving independently of one another towards action, corresponding with the multiplicity of instincts and of relations with the external world, may of which are antagonistic to one another and incompatible. For proper functioning it is necessary that the highest of these agencies should have knowledge of all that is going forward and that its will should penetrate everywhere, so as to exert its influence. And in fact the ego feels secure both as to the completeness and trustworthiness of the reports it receives and as to the openness of the channels through which it enforces its commands. [Q302, Freud, 1917d, p.141]
  • Even if you are not ill, who can tell all that is stirring in your mind of which you know nothing or are falsely informed? You behave like an absolute ruler who is content with the information supplied him by his highest officials and never goes among the people to hear their voice. Turn your eyes inward, look into your own depths, learn first to know yourself! [Q303, Freud, 1917d, p. 143]
  • It is thus that psycho-analysis has sought to educate the ego. But these two discoveries – that the life of our sexual [impulses] cannot be wholly tamed, and that mental processes are in themselves unconscious and only reach the ego and come under its control through incomplete and untrustworthy perceptions – these two discoveries amount to a statement that the ego is not master in its own house. Together they represent the third blow to man’s self-love, what I may call the psychological one. No wonder, then, that the ego does not look favourably upon psycho-analysis and obstinately refuses to believe in it. [Q304, Freud, 1917d, p. 143b]
  • Man’s archaic heritage forms the nucleus of the unconscious mind: and whatever part of that heritage has to be left behind in the advance to later phases of development, because it is unserviceable or incompatible with what is new and harmful to it, falls a victim to the process of repression. [Q305, Freud, 1917d, p. 204]

Standard Edition, Volume 18. Beyond the Pleasure Principle, Group Psychology & Other Works. 1920-1922.

  • In taking that course into account in our consideration of the mental processes which are the subject of our study, we are introducing an ‘economic’ point of view into our work; and if, in describing those processes, we try to estimate this ‘economic’ factor in addition to the ‘topographical’ and ‘dynamic’ ones, we shall, I think, be giving the most complete description of them of which we can at present conceive, and one which deserves to be called ‘metapsychological’. [Q306, Freud, 1920, p. 7]
  • The mental apparatus endeavours to keep the quantity of excitation present in it as low as possible or at least to keep it constant… Moreover, a more detailed discussion will show that the tendency which we thus attribute to the mental apparatus is subsumed as a special case under Fechner’s principle of the ‘tendency towards stability’. [Q307, Freud, 1920, p. 9]
  • Another occasion of the release of unpleasure, which occurs with no less regularity, is to be found in the conflicts and dissentions that take place in the mental apparatus while the ego is passing through its development into more highly composite organisations. Almost all the energy with which the apparatus is filled arises from its innate instinctual impulses. But these are not all allowed the same phases of development. In the course of things it happens again and again that individual impulses or parts of impulses turn out to be incompatible in their aims or demands with the remaining ones, which are able to combine into the inclusive unity of the ego. The former are then split off from this unity by the process of repression, held back at lower levels of psychical development and cut off, to begin with, from the possibility of satisfaction. [Q308, Freud, 1920, p.11]
  • It is certain that much of the ego is unconscious. [Q309, Freud, 1920, p. 19]
  • Protection against stimuli is an almost more important function for the living organism than reception of stimuli. The protective shield is supplied with its own store of energy and must above all endeavour to preserve the special modes of transformation of energy operating in it against the effects threatened by the enormous energies at work in the external world – effects which tend towards a levelling out of them and hence towards destruction. The main purpose of the reception of stimuli is to discover the direction and nature of the external stimuli; and for that it is enough to take small specimens of the external world, to sample it in small quantities. In highly developed organisms the receptive cortical layer of the former vesicle has long been withdrawn into the depths of the interior of the body, though portions of it have been left behind on the surface immediately beneath the general shield against stimuli. These are the sense organs, which consist essentially of apparatus for the reception of certain specific effects of stimulation, but which also include special arrangements for further protection against excessive amounts of stimulation and for excluding unsuitable kinds of stimuli. It is characteristic of them that they only deal with very small quantities of external stimulation and only take in samples of the external world. They may perhaps be compared with feelers which are all the time making tentative advances towards the external world and then drawing back from it. [Q310, Freud, 1920, p. 27-28]
  • We have learnt that unconscious mental processes are in themselves ‘timeless’. This means in the first place that they are not ordered temporally, that time does not change them in any way and that the idea of time cannot be applied to them. These are negative characteristics which can only be clearly understood if a comparison is made with conscious mental processes. On the other hand, our abstract idea of time seems to be wholly derived form the method of working of the perceptual system and to correspond to a perception on its own. [Q311, Freud, 1920, p. 28b]
  • A particular way is adopted of dealing with any internal excitations which produce too great an increase of unpleasure: there is a tendency to treat them as though they were acting, not from the inside but from the outside, so that it may be possible to bring the shield against stimuli into operation as a means of defence against them. This is the origin of projection, which is destined to play such a large part in the causation of pathological processes. [Q312, Freud, 1920, p. 29]
  • We describe as ‘traumatic’ any excitations from outside which are powerful enough to break through the protective shield. It seems to me that the concept of trauma necessarily implies a connection of this kind with a breach in an otherwise efficacious barrier against stimuli. [Q313, Freud, 1920, p. 29]
  • We infer that a system which is itself highly activated is capable of taking up an additional stream of fresh inflowing energy and of converting it into quiescent energy, that is of binding it psychically. The higher the system’s own quiescent energy, the greater seems to be its binding force; conversely, therefore, the lower the activation, the less capacity will it have for taking up inflowing energy. [Q314, Freud, 1920, p. 30]
  • The indefiniteness of all our discussions on what we describe as metapsychology is of course due to the fact that we know nothing of the nature of the excitatory process that takes place in the elements of the psychical systems, and that we do not feel justified in framing any hypothesis on the subject. We are consequently operating all the time with a large unknown factor, which we are obliged to carry over into every new formula. It may be reasonably supposed that this excitatory process can be carried out with energies that vary quantitatively; it may also seem probable that it has more than one quality (in the nature of amplitude, for instance). As a new factor we have taken into consideration Breuer’s hypothesis that charges of energy occur in two forms; so that we have distinguish between two kinds of activations of the psychical systems or their elements – a freely flowing activation that presses on towards discharge and a quiescent activation. We may perhaps suspect that the binding of the energy that streams into the mental apparatus consists in its change from a freely flowing into a quiescent state. [Q315, Freud, 1920, p. 31]
  • The fact that the cortical layer which receives stimuli is without any protective shield against excitations from within must have as its result that these latter transmissions of stimulus have a preponderance in economic importance and often occasion economic disturbances comparable with traumatic neuroses. The most abundant sources of this internal excitation are what are described as the organism’s drives – the representatives of all the forces originating in the interior of the body and transmitted to the mental apparatus – at once the most important and the most obscure element of psychological research. It will perhaps not be thought too rash to suppose that the impulses arising from the drives do not belong to the type of bound nervous processes but of freely mobile processes which press towards discharge. The best part of what we know of these processes is derived from our study of the dream-work… In the unconscious, energy can easily be transferred, displaced and condensed. [Q316, Freud, 1920, p. 34]
  • I described the type of process found in the unconscious as the ‘primary’ psychical process, in contradistinction to the secondary process which is the one obtaining in our normal waking life. Since all instinctual impulses have the unconscious systems as their point of impact, it is hardly an innovation to say that they obey the primary process. Again, it is easy to identify the primary psychical process with Breuer’s freely mobile activity and the secondary process with changes in his bound or tonic activity. [Q317, Freud, 1920, p.34]
  • It may be presumed too that when people unfamiliar with analysis feel an obscure fear – a dread of rousing something that, so they feel, is better left sleeping – what they are afraid of at bottom is the emergence of [a] compulsion with its hint of possession by some ‘daemonic’ power. [Q318, Freud, 1920, p. 36]
  • It seems that a drive is an urge inherent in organic life to restore an earlier state of things which the living entity has been obliged to abandon under the pressure of external disturbing forces; that is, it is a kind of organic elasticity, or to put it another way, the expression of the inertia inherent in organic life. [Q319, Freud, 1920, p. 36]
  • Advancing more cautiously, psycho-analysis observed the regularity with which libido is withdrawn from the object and directed on to the ego (the process of introversion); and, by studying the libidinal development of children in its earliest phases came to the conclusion that the ego is the true and original reservoir of libido and it is only from this reservoir that libido is extended on to objects. [Q320, Freud, 1920, p. 52]
  • We have found that one of the earliest and most important functions of the mental apparatus is to bind the instinctual impulses which impinge on it, to replace the primary process prevailing in them by the secondary process and convert their freely mobile energy into a mainly quiescent (tonic) activity. [Q321, Freud, 1920, p. 62]
  • This raises the question whether feelings of pleasure and unpleasure can be produced equally from bound and from unbound excitatory processes. And there seems to be no doubt whatever that the unbound or primary processes give rise to far more intense feelings in both directions than the bound or secondary ones… In any case, whatever it is that causes the appearance of feelings of pleasure and unpleasure in processes of excitation must be present in the secondary process just as it is in the primary one. [Q322, Freud, 1920, p. 63]
  • On previous occasions we have been driven to the hypothesis that some such agency develops in our ego which may cut itself off from the rest of the ego and come into conflict with it. We have called it the ‘ego ideal’ and by way of functions we have ascribed to it self-observation, the moral conscience, the censorship in dreams, and the chief influence in repression. We have said that it is heir to the original narcissism in which the childish ego enjoyed self-sufficiency; it gradually gathers up from the influences of the environment the demands which that environment makes upon the ego and which the ego cannot always rise to; so that a man, when he cannot be satisfied with his ego itself, may nevertheless be able to find satisfaction in the ego-ideal which has been differentiated out of the ego. In delusions of observation, as we have further shown, the disintegration of this agency has become patent, and has thus revealed its origin in the influence of superior powers and above all of the parents. [Q323, Freud, 1920, p. 110]
  • Speech owes its importance to its aptitude for mutual understanding in the herd, and upon it the identification of the individuals with one another largely rests. [Q324, Freud, 1920, p. 118]
  • In the course of our development we have effected a separation of our mental existence into a coherent ego and into an unconscious and repressed portion which is left outside of it. [Q325, Freud, 1920, p. 131]
  • The sense of guilt (as well as the sense of inferiority) can also be understood as an expression of tension between the ego and the ego ideal. [Q326, Freud, 1920, p. 131b]
  • To this day psycho-analysis is looked upon as one savouring of mysticism… But if we look closer, difficulties begin to emerge… Analysts are at bottom incorrigible mechanists and materialists, even though they seek to avoid robbing the mind and spirit of their still unrecognisable characteristics. So too, they embark on the investigation of occult phenomena only because they expect in that way finally to exclude the [wishful thinking] of mankind from material reality [i.e., from science]. [Q327, Freud, 1921, p. 179]
  • The neuroses are the expression of conflicts between the ego and such of the sexual impulses as seem to the ego incompatible with its integrity or with its ethical standards. Since these impulse are not ego-syntonic, the ego has repressed them: that is to say, it has withdrawn its interest from them and has shut them off from becoming conscious. [Q328, Freud, 1922, p. 246]
  • The ego itself came to be regarded as a reservoir of what was described as narcissistic libido, from which the libidinal energy of objects flowed out and into which they could be once more withdrawn… The narcissistic disorders (dementia praecox, paranoia, melancholia) are characterised by a withdrawal of the libido from objects and they are therefore scarcely assessable to analytic therapy. [Q329, Freud, 1922, p. 249]
  • The pathogenic process in dementia praecox is the withdrawal of the libido from objects and its introduction into the ego, while the clamorous symptoms of the ideas arise from the vain struggles of the libido to find a pathway back to objects. [Q330, Freud, 1922, p. 257]
  • The ego is to be regarded as a great reservoir of libido from which libido is sent out to objects and which is always ready to absorb libido flowing back from [Q331, Freud, 1922, p. 257b]
  • For that reason I think it advisable, when establishing a distinction between the different modes of thought-activity, not to utilise the relation to consciousness in the first instance, and to designate the day-dream… as freely wandering or fantastic thinking, in opposition to intentionally directed reflection. [Q332, Freud, 1921, p. 272]

Standard Edition, Volume 19. The Ego and the Id and Other Works. 1923-1925.


  • To most people who have been educated in philosophy the idea of anything psychical which is not also conscious is so inconceivable that it seems to them absurd and refutable simply by logic. I believe this is only because they have never studied the relevant phenomena of hypnosis and dreams, which – quite apart from pathological manifestations – necessitate this view. Their psychology of consciousness is incapable of solving the problems of dreams and hypnosis. [Q333, Freud, 1923, p. 13]
  • In each individual there is a coherent organisation of mental processes; and we call this his ego. It is to this ego that consciousness is attached; the ego controls the approaches to motility – that is, to the discharge of excitation into the external world. [Q334, Freud, 1923, p. 17]
  • We have come upon something in the ego itself which is also unconscious, which behaves exactly like the repressed – that is, which produces powerful effects without itself being conscious and which requires special work before it can be made conscious. [Q335, Freud, 1923, p. 17]
  • We have said that consciousness is the surface of the mental apparatus; that is, we have ascribed it as a function to a system [the perceptual system] which is spatially the first one reached from the external world – and spatially not only in the functional sense but on this occasion also in the sense of anatomical dissection. [Q336, Freud, 1923, p. 19]
  • Thinking in pictures [fantasy] is only a very incomplete form of becoming conscious. In some way, too, it stands nearer to unconscious processes than does thinking in words, and it is unquestionably older than the latter, both ontogenetically and phylogenetically. [Q337, Freud, 1923, p. 21]
  • Whereas the relation of external perceptions to the ego is quite perspicuous, that of internal perceptions to the ego requires special investigation. It gives rise once more to a doubt whether we are really right in referring the whole of consciousness to the single superficial perceptual system. [Q338, Freud, 1923, p. 21b]
  • We shall now look upon an individual as a psychical id, unknown and unconscious, upon whose surface rests the ego… The ego is not sharply separated from the id; its lower portion merges into it. [Q339, Freud, 1923, p. 24]
  • It is easy to see that the ego is that part of the id which has been modified by the direct influence of the external world through the medium of the perceptual system; in a sense it is an extension of the surface differentiation. Moreover, the ego seeks to bring the influence of the external world to bear upon the id and its tendencies… For the ego, perception plays the part which in the id falls to drive. The ego represents what may be called reason and common sense, in contrast to the id, which contains the passions. [Q340, Freud, 1923, p. 25]
  • Thus, in its relation to the id [the ego] is like a man on horseback, who has to hold in check the superior strength of the horse… Often a rider, if he is not to be parted from his horse, is obliged to guide it where it wants to go; so in the same way the ego is in the habit of transforming the id’s will into action as if it were its own. [Q341, Freud, 1923, p. 25]
  • The ego is first and foremost a bodily ego. [Q342, Freud, 1923, p. 26]
  • If we are to come back once more to our scale of values, we shall have to say that not only what is lowest but also what is highest in the ego can be unconscious. [Q343, Freud, 1923, p. 27]
  • If we consider once more the origin of the super-ego as we have described it, we shall recognise that it is the outcome of two highly important factors, once biological and the other of a historical nature: namely, the lengthy duration in man of his childhood helplessness and dependence, and the fact of his Oedipus complex, the repression of which we have shown to be connected with the interruption of libidinal development by the latency period and so with the diphasic onset of man’s sexual life. According to one psycho-analytic hypothesis, the last-mentioned phenomenon, which seems to be peculiar to man, is a heritage of the cultural development necessitated by the glacial epoch. We see, then, that the differentiation of the super-ego from the ego is no matter of chance; it represents the most important characteristics of the development both of the individual and of the species, indeed, by giving permanent expression to the influence of the parents it perpetuates the existence of the factors to which it owes its origin. [Q344, Freud, 1923, p. 35]
  • The ego-ideal is therefore heir to the Oedipus complex and this it is also the expression of the most powerful impulses and most important libidinal vicissitudes of the id. By setting up this ego ideal, the ego has mastered the Oedipus complex and at the same time placed itself in subjection to the id. Whereas the ego is essentially the representative of the external world, of reality, the super-ego stands in contrast to it as the representative of the internal world, of the id. [Q345, Freud, 1923, p. 36]
  • Through the forming of the ideal, what biology and the vicissitudes of the human species have created in the id and left behind in it is taken by the ego and re-experienced in relation to itself as an individual. Owing to the way in which the ego-ideal is formed, it has the most abundant links with the phylogenetic acquisition of each individual – this archaic heritage. What has belonged to the lowest part of the mental life of each of us in changed, through the formation of the ideal, into what is highest in the human mind by our scale of values. It would be in vain, however, to attempt to localise the ego ideal. Even in the sense in which we have localised the ego, or to work it into any of the analogies with the help of which we have tried to picture the relation between the ego and the id. [Q346, Freud, 1923, p. 36-37]
  • The differentiation between ego and id must be attributed not only to primitive man but even to much simpler organisms, for it is the inevitable expression of the influence of the external world. [Q347, Freud, 1923, p. 38]
  • Reflection at once shows us that no external vicissitudes can be experienced or undergone by the id, except by way of the ego, which is the representative of the external world to the id. Nevertheless it is not possible to speak of direct inheritance in the ego. It is here that the gulf between an actual individual and the concept of a species becomes evident. Moreover, one must not take the difference between ego and id in too hard-and-fast a sense, nor forget that the ego is a specially differentiated part of the id. The experiences of the ego seem at first to be lost for inheritance; but, when they have been repeated often enough and with sufficient strength in many individuals in successive generations, they transform themselves, so to say, into experiences of the id, the impressions of which are preserved by heredity. Thus in the id, which is capable of being inherited, are harboured residues of the existences of countless egos; and, when the ego forms its super-ego out of the id, it may perhaps only be reviving shapes of former egos and be bringing them to resurrection. [Q348, Freud, 1923, p. 38]
  • The way in which the super-ego came into being explains how it is that the early conflicts of the ego with the object-investments of the id can be continued in conflicts with their heir, the super-ego. If the ego has not succeeded in properly mastering the Oedipus complex, the energetic activation of the latter, springing from the id, will come into operation once more in the reaction-formation of the ego-ideal. The abundant communication between the ideal and these Ucs instinctual impulses solves the puzzle of how it is that the ideal itself can to a great extent remain unconscious and inaccessible to the ego. The struggle which once raged in the deepest strata of the mind, and was not brought to an end by rapid sublimation and identification, is now continued in a higher region, like the Battle of the Huns in Kaulbach’s painting. [Q349, Freud, 1923, p. 38-39]
  • We have already concluded that the ego is especially under the influence of perception, and that, speaking broadly, perceptions may be said to have the same significance for the ego as drives have for the id. [Q350, Freud, 1923, p. 40]
  • The ego deals with the first object-investments of the id (and certainly later ones too) by taking over the libido from them into itself and binding it to the alteration of the ego. [Q351, Freud, 1923, p. 46]
  • At the very beginning, all the libido is accumulated in the id, while the ego is still in process of formation or is still feeble. The id sends part of this libido out into erotic object-investments, whereupon the ego, now grown stronger, tries to get hold of this object-libido and to force itself on the id as a love-object. The narcissism of the ego is thus a secondary one, which has been withdrawn from objects. [Q352, Freud, 1923, p. 46b]
  • If it is true that Fechner’s principle of constancy governs life. [Q353, Freud, 1923, p. 47]
  • The feelings of inferiority so well known in neurotics are presumably not far removed from it. In two very familiar maladies the sense of guilt is over-strongly conscious; in them the ego ideal displays particular severity and often rages against the ego in a cruel fashion. [Q354, Freud, 1923, p. 51]
  • In certain forms of obsessional neurosis the sense of guilt in over-noisy but cannot justify itself to the ego. [Q355, Freud, 1923, p. 51b]
  • By virtue of [the ego’s] relation to the perceptual system it gives mental processes an order in time and submits them to reality-testing. By interposing processes of thinking, it secures a postponement of motor discharges and controls the access to motility. [Q356, Freud, 1923, p. 55]
  • All the experiences of life that originate from without enrich the ego; the id, however, is its second external world, which it strives to bring into subjection to itself. It withdraws libido from the id and transforms the object-investments of the id into ego structures. With the aid of the super-ego, in a manner that is still obscure to us, it draws upon the experiences of past ages stored in the id. [Q357, Freud, 1923, p. 55b]
  • There are two paths by which the contents of the id can penetrate into the ego. The one is direct, the other leads by way of the ego ideal; which of these two paths they take may, for some mental activities, be of decisive importance. The ego develops from perceiving impulses to controlling them, from obeying impulses to inhibiting them. [Q358, Freud, 1923, p. 56]
  • The id, to which we finally come back, has no means of showing the ego either love or hate. It cannot say what it wants; it has achieved no unified will. [Q359, Freud, 1923, p. 59]
  • But this ego developed out of the id, it forms with it a single biological unit, it is only a specially modified peripheral portion of it, and it is subject to the influences and obeys the suggestions that arise from the id. For any vital purpose, a separation of the ego from the id would be a hopeless undertaking. [Q360, Freud, 1925, p. 133]
  • Conscience is no doubt a reaction formation against the evil that is perceived in the id. [Q361, Freud, 1925, p. 134]
  • In undertaking the repression, the ego is at bottom following the commands of its super-ego – commands which, in their turn, originate from influences in the external world that have found representation in the super-ego. The fact remains that the ego has taken sides with those powers, that in it their demands have more strength than the instinctual demands of the id, and that the ego is the power which sets repression in motion against the portions of the id concerned and which fortifies the repression by means of the [inhibitory force] of resistance. The ego has come into conflict with the id in the service of the super-ego. [Q362, Freud, 1924, p. 150]
  • Normally, the external world governs the ego in two ways: firstly, by current, present perceptions which are always renewable, and secondly by the store of memories of earlier perceptions which, in the shape of an ‘internal world’, form a possession of the ego and a constituent part of it. [Q363, Freud, 1924, p. 150b]
  • Delusion is found like a patch over the place where originally a rent had appeared in the ego’s relation to the external world. [Q364, Freud, 1924, p. 151]
  • The pathogenic effect depends on whether, in a conflictual tension of this kind, the ego remains true to its dependence on the external world and attempts to silence the id or whether it lets itself by overcome by the id and thus torn away from reality. [Q365, Freud, 1924, p. 151b]
  • It will be remembered that we have taken the view that the principle which governs all mental processes is a special case of Fechner’s ‘tendency towards stability’, and have accordingly attributed to the mental apparatus the purpose of reducing to nothing, or at least of keeping as low as possible, the sums of excitation which flow in upon it. Barbara Low has suggested the name of ‘Nirvana principle’ for this supposed tendency, and we have accepted the term. [Q366, Freud, 1924b, p. 159]
  • The super-ego is as much a representative of the id as of the external world. It came into being through the introjection into the ego of the first objects of the id’s libidinal impulses – namely, the two parents. [Q367, Freud, 1924b, p. 167]
  • I have recently indicated as one of the features which differentiate a neurosis from a psychosis the fact that in a neurosis the ego, in its dependence of reality, suppresses a piece of the id (of instinctual life), whereas in a psychosis, the same ego, is the service of the id, withdraws from a piece of reality. [Q368, Freud, 1924c]
  • The fact that, in so many forms and cases of psychosis… the paramnesias, the delusions and the hallucinations that occur are of a most distressing character and are bound up with the generation of anxiety – this fact is without doubt a sign that the whole process of remodelling is carried through against the forces which oppose it violently. [Q369, Freud, 1924c]
  • The sharp distinction between neurosis and psychosis, however, is weakened by the circumstance that in neurosis, too, there is no lack of attempts to replace a disagreeable reality by one which is more in keeping with the subject’s wishes. This is made possible by the existence of a world of fantasy, of a domain which became separated from the real external world at the time of the introduction of the reality principle. This domain has since been kept free from the demands of the exigencies of life, like a kind of reservation. [Q370, Freud, 1924c]
  • It can hardly be doubted that the world of fantasy plays the same part in psychosis and that there too it is the storehouse from which the materials or the patterns for building the new reality are derived. [Q371, Freud, 1924c]
  • I have recently proposed of dividing the mental apparatus into an ego, turned towards the external world and equipped with consciousness, and an unconscious id, dominated by its instinctual needs, then psycho-analysis is to be described as a psychology of the id (and of its effects on the ego). [Q372, Freud, 1924d]
  • The other sort of decision made by the function of judgement – as to the real existence of something of which there is a presentation (reality-testing) – is a concern of the definitive reality-ego… It is now no longer a question of whether what has been perceived (a thing) shall be taken into the ego or not, but of whether something which is in the ego as a presentation can be rediscovered in perception (reality) as well. [Q373, Freud, 1924d]
  • Judging is the intellectual action which decides the choice of motor action, which puts an end to the postponement due to thought and which leads over from thinking to acting. [Q374, Freud, 1925b, p. 238]
  • For on our hypothesis, perception is not a purely passive process. The ego periodically sends out small amounts of energy into the perceptual system by means of which it samples the external stimuli and then after every such tentative advance it draws back again. [Q375, Freud, 1925b, p. 238b]
  • This view of negation fits in very well with the fact that in analysis we never discover a ‘no’ in the unconscious and that recognition of the unconscious on the part of the ego is expressed in a negative formula. There is no stronger evidence that we have been successful in our effort to uncover the unconscious than when the patient reacts to it with the words ‘I didn’t think that’ or ‘I didn’t (ever) think of that’. [Q376, Freud, 1925b, p. 239]

Standard Edition, Volume 20. An Autobiographical Study, Inhibitions, Symptoms and Anxiety, Lay Analysis and Other Works. 1925-1926.


  • The dividing of the conscious and the unconscious into various psychical systems – then psychoanalysis was no longer an auxiliary science in the field of psychopathology, it was rather the starting point if a new and deeper science of the mind which would be equally indispensable for the understanding of the normal. Its postulates and findings could be carried over to other regions of the mental happening; a path lay open to it that led far a field, into spheres of universal interest. [Q377, Freud, 1925c, p.47]
  • There followed form this fact the concept (of fundamental importance to libido theory) of a state in which the subject’s libido filled his own ego and had that for its object. This state could be called narcissism or self-love. A moment’s reflection showed that this state never completely ceases. All through the subject’s life his ego remains the great reservoir of libido, from which object-investments are sent out and into which the libido can stream back again from the objects. Thus narcissistic libido is constantly being transformed into object-libido and vice versa. [Q378, Freud, 1925c, p. 56]
  • I was always open to the ideas of G.T. Fechner and have followed that thinker upon many points. [Q379, Freud, 1925c, p. 59]
  • It seems to me that the ego obtains this influence in virtue of its intimate connections with the perceptual system – connections which, as we know, constitute its essence and provide the basis of its differentiation from the id. The function of this system, which we have called the perceptual system is bound up with the phenomenon of consciousness. [Q380, Freud, 1926, p. 92]
  • Just as the ego controls the path to action in regard to the external world, so it controls access to consciousness. [Q381, Freud, 1926, p. 95]
  • We know well enough how little light science has so far been able to throw on the problems that surround us. But however much ado the philosophers make, they cannot alter the situation. Only patient, persevering research, in which everything is subordinated to the one requirement for certainty, can gradually bring about change. The benighted traveller may sing aloud in the dark to deny his own fears; but for all that, he will not see an inch further in front of his nose. [Q382, Freud, 1926, p. 96]
  • We were justified, I think, in dividing the ego from the id, for there are certain considerations which necessitate that step. On the other hand the ego is identical with the id and is merely a specially differentiated part of it. If we think of this part by itself in contradistinction to the whole, or if a real split has occurred between the two, the weakness of the ego becomes apparent. But if the ego remains bound up with the id and indistinguishable from it, then it displays its strength. [Q383, Freud, 1926, p. 97]
  • In repression the decisive fact is that the ego is an organisation and the id is not. The ego is indeed the organised portion of the id. [Q384, Freud, 1926, p. 97b]
  • The ego is an organisation. It is based on the maintenance of free intercourse and of the possibility of reciprocal influence between all its parts. Its desexualised energy still shows traces of its origin in its impulsion to bind together and unify, and this necessity to synthesise grows stronger in proportion as the strength of the ego increases. It is therefore only natural that the ego should try to proven symptoms from remaining isolated and alien by using every possible method to bind them to itself in one way or another; and to incorporate them into its organisation by means of those bonds. [Q385, Freud, 1926, p. 98]
  • It is always the ego’s attitude of anxiety which is the primary thing and which sets repression going. [Q386, Freud, 1926, p. 109]
  • But even a normal person uses concentration to keep away not only what is irrelevant or unimportant but above all, what is unsuitable because it is contradictory. [Q387, Freud, 1926, p. 121]
  • Anxiety is an affective state and as such can, of course, only be felt by the ego. The id cannot have anxiety as the ego can; for it is not an organisation and cannot make a judgment about situations of danger. [Q388, Freud, 1926, p. 140]
  • This is inevitable from the nature of repression, which, is fundamentally an attempt at flight. The repressed is now, as it were, an outlaw; it is excluded from the great organisation of the ego and is subject only to the laws which govern the realm of the unconscious. [Q389, Freud, 1926, 153]
  • This has led us to suppose that something momentous must have occurred in the vicissitudes of the human species [events related to the glacial epoch] which has left behind this interruption in the sexual development of the individual as a historical precipitate. [Q390, Freud, 1926, p. 155]
  • In view of the dangers of external reality, the ego is obliged to guard against certain instinctual impulses in the id and to treat them as dangers. But it cannot protect itself from internal instinctual dangers as effectively as it can from some piece of reality that is not part of itself. Intimately bound up with the id as it is, it can only fend off an instinctual danger by restricting its own organisation and by acquiescing in the formation of symptoms in exchange for having impaired the impulse. If the rejected impulse renews its attack, the ego is overtaken by all those difficulties which are known as neurotic ailments. [Q391, Freud, 1926, p. 156]
  • We recognise is human beings a mental organisation which is interpolated between their sensory stimuli and the perception of their somatic needs on the one hand and their motor acts on the other, and which mediates between them for a particular purpose. We call this organisation their ‘Ich’ [‘ego’; literally, ‘I’]… Besides this ‘I’, we recognise another mental region, more extensive, more imposing and more obscure than the ‘I’, and this w call the ‘Es’ [‘id’; literally, ‘it’]. The relation between the two must be our immediate concern. [Q392, Freud, 1926b, p. 195]
  • I must ask you to picture the ego as a kind of façade of the id, as a frontage, like an external, cortical layer of it… We suppose that the ego is the layer of the mental apparatus (of the id) which has been modified by the influence of the external world (of reality). [Q393, Freud, 1926b, p. 195b]
  • The ego lies between reality and the id. [Q394, Freud, 1926b, p. 196]
  • The rules governing the course of mental acts are different in the ego and the id. [Q395, Freud, 1926b, p. 196b]
  • In the id there are no conflicts; contradictions and antithesis persist side by side unconcernedly. [Q396, Freud, 1926b, p. 196c]
  • The ego is an organisation characterised by a very remarkable trend towards unification, towards synthesis. This characteristic is lacking in the id. [Q397, Freud, 1926b, p. 196d]
  • Now, we believe that on the outermost surface of this ego there is a special agency directed immediately to the external world, a system … through the excitation of which alone the phenomenon that we call consciousness comes about. This organ can be equally excited from outside – thus receiving (with the help of the sense-organs) the stimuli from the external world – and from inside – thus becoming aware, first of the sensations in the id and then also of the processes in the ego. [Q398, Freud, 1926b, p. 198]
  • ‘Triebe’ [drive], a word for which we are envied by many modern languages. Well these drives fill the id: all the energy of the id, as we may put it briefly, originates from them. Nor have the forces of the ego any other origin; they are derived from those in the id. [Q399, Freud, 1926b, p. 200]
  • At that point the portion of the id which is directed towards the external world – the ego – begins to function. If all the driving force that sets the vehicle in motion is derived from the id, the ego, as it were, undertakes the steering, without which no goal can be reached. [Q400, Freud, 1926b, p. 201]
  • [The ego] carried on its activity in two directions. On the one hand, it observes the external world with the help of its sense-organ, the system of consciousness, so as to catch the favourable moment for harmless satisfaction; and on the other hand it influences the id, bridles its passion, induces its drives to postpone their satisfaction. [Q401, Freud, 1926b, p. 201b]
  • Yes, all will be well if the ego is in possession of its whole organisation and efficiency, if it has access to all parts of the id and can exercise its influence on them. For there is not natural opposition between ego and id; they belong together, and under healthy conditions cannot in practice be distinguished from each other. [Q402, Freud, 1926b, p. 201c]
  • The decisive repressions all take place in childhood. [Q403, Freud, 1926b, p. 202]
  • The super-ego occupies a special position between the ego and the id. It belongs to the ego and shares its high degree of psychological organisation; but it has a particularly intimate connection with the id. It is in fat a precipitate of the first object-investments of the id and is heir to the Oedipus complex after its demise. The super-ego can confront the ego and treat it like an object and it often treats it very harshly… The super-ego is the vehicle of the phenomenon that we call conscience. [Q404, Freud, 1926b, p. 223]
  • Illness is employed as an instrument for this ‘self-punishment’. And neurotics have to behave as though they were governed by a sense of guilt which, in order to be satisfied, needs to be punished by illness. [Q405, Freud, 1926b, p. 223b]
  • Under the extraordinary burden of this period of childhood – we have in a few years to cover the enormous developmental distance between stone-age primitive mend and the participants in contemporary civilisation, and, at the same time and in particular, we have to fend off the instinctual impulses of the early sexual period – under this burden, then. Our ego takes refuge in repression and lays itself open to a childhood neurosis, the precipitate of which it carried with it into maturity as a disposition to a later nervous illness. Everything now depends on how the growing organism is treated by fate. If life becomes too hard, if the gulf between impulsive claims and the demands of reality become too great, the ego may fail in its efforts to reconcile the two, and the more readily, the more it is inhibited by the disposition carried over by it from infancy. The process of repression is then repeated, the drives tear themselves away from the ego’s domination, find their substitutive satisfactions along the paths of regression, and the poor ego has become helplessly neurotic. [Q406, Freud, 1926b, p. 241-242]
  • But the relative feebleness of the ego [e.g., the childhood ego] is the decisive factor for the genesis of a neurosis, it must also be possible for a later physical illness to produce a neurosis provided that it can bring about an enfeeblement of the ego. And that, once again, is very frequently found. A physical disorder of this kind can affect the instinctual life of the id and increase the strength of the drives beyond a certain limit up to which the ego is capable of coping with them. The normal model of such process is perhaps the alteration in women caused by the disturbance of menstruation and the menopause. [Q407, Freud, 1926b, p. 242b]
  • As a depth psychology, a theory of the mental unconscious, [psychoanalysis] can become indispensable to all the sciences which are concerned with the evolution of human civilisation and its major institutions such as art, religion and the social order. [Q408, Freud, 1926b, p. 248]
  • I share the view that all those problems which relate to the connection between psychical phenomena and their organic, anatomical and chemical foundation can be approached only by those who have studied both, that is, by medical analysts. [Q409, Freud, 1926b, p. 257]
  • From the economic standpoint psycho-analysis supposes that the mental representatives of the drives have a charge of definite quantities of energy, and that it is the purpose of the mental apparatus to hinder any damming-up of these energies and to keep as low as possible the total amount of the excitations with which it is loaded. [Q410, Freud, 1926b, p. 266]
  • According to the most recent psycho-analytic views, the mental apparatus is composed of an ‘id’, which is the repository of the impulses, or an ego, which is the most superficial portion of the id and one which has been modified by the influence of the external world; and of a ‘super-ego’ which develops out of the id, dominates the ego and represents the inhibitions of drives that are characteristic of man. [Q411, Freud, 1926b, p. 266b]
  • It must not be supposed that these very general ideas are presuppositions upon which the work of psycho-analysis depends. On the contrary, they are its latest conclusions and are ‘open to revision’. Psycho-analysis is founded securely upon the observation of the facts of mental life and for that reason its theoretical superstructure is still incomplete and subject to constant alteration. [Q412, Freud, 1926b, p. 266c]

Standard Edition, Volume 21. The Future of an Illusion, Civilisation and its Discontents and Other Works. 1927-1931.


  • Normally, there is nothing of which we are more certain than the feeling of our self, of our own ego. This ego appears to us as something autonomous and unitary, marked off distinctly from everything else. Such an appearance is deceptive… on the contrary the ego is continued inwards, without any sharp delimitation into an unconscious mental entity which we designate as the id and for which it serves as a kind of façade. [Q413, Freud, 1930, p. 66]
  • Further reflection tells us that the adult’s ego feeling cannot have been the same from the beginning. It must have gone through a process of development. [Q414, Freud, 1930, p. 66]
  • Originally the ego includes everything, later is separates off an external world from itself. Our present ego-feeling is therefore a shrunken residue of a much more inclusive – indeed all-embracing – feeling which corresponded to a more intimate bond between the ego and the world about it… the ideational content appropriate to it would be precisely those of limitlessness and of a bond with the universe – the same ideas with which my friend elucidated the ‘oceanic’ feeling. [Q415, Freud, 1930, p. 68]
  • The ego itself is activated with libido, the ego, indeed, is the libido’s original home, and remains to some extent its headquarters. [Q416, Freud, 1930, p. 118]
  • The essential difference between neurosis and psychosis [is] that in the former, the ego, in the service of reality, suppresses a piece of the id, whereas in a psychosis it lets itself be induced by the id to detach itself from a piece of reality. [Q417, Freud, 1927, p. 155]
  • The cure too of such paranoic attacks would lie not so much in a resolution and correction of the delusional ideas as in a withdrawal from them of the energy which has been lent to them. The alternations between melancholia and mania, between a cruel suppression of the ego by the super-ego and a liberation of the ego after that pressure, suggests a shift of energy of this kind. [Q418, Freud, 1927, p. 165]

Standard Edition, Volume 22. New Introductory Lectures on Psycho-Analysis and Other Works. 1932-1936.


  • In psychosis, however, the turning away from reality is brought about in two kinds of way: either by the unconscious repressed becoming excessively strong so that it overwhelms the conscious which is attached to reality, or because reality has become so intolerably distressing that the threatened ego throws itself into the arms of the unconscious impulsive forces in a desperate revolt. [Q419, Freud, 1933, p. 16]
  • The processes which take place in the unconscious system… has shown us that they are quite other than what we know from our conscious thinking and are bound to appear to the latter preposterous and incorrect. [Q420, Freud, 1933, p. 17]
  • The ego can take itself as an object, can treat itself like other objects, can observe itself, criticise itself, and do Heaven knows what with itself. In this, one part of the ego is setting itself over against the rest [i.e., the super-ego over the ego]. So the ego can be split; it splits itself during a number of its functions – temporarily at least. Its parts can come together afterwards. [Q421, Freud, 1933, p. 58]
  • We perceive that we have no right to name the mental region that is foreign to the ego ‘the system Ucs’, since the characteristics of being unconscious is not restricted to it. Very well; we will no longer use the term ‘unconscious’ in the systematic sense and we will give what we have hitherto described a better name and one no longer open to misunderstanding. Following a verbal usage of Nietzsche’s and taking up a suggestion by Georg Groddeck, we will in future call it the ‘Es’ [i.e., ‘it’, the ‘id’]. [Q422, Freud, 1933, p. 72]
  • You will not expect me to have much to tell you that is new about the id apart from its new name. It is the dark, inaccessible part of our personality; what little we know of it we learnt from our study of dream-work and of the construction of neurotic symptoms and most of that is of a negative character and can be described only as a contrast to the ego. We approach the id with analogies: we call it a chaos, a cauldron full of seething excitations… It is filled with energy reaching it from the drives but it has no organisation, produces no collective will… The logical laws of thought do not apply in the id, and this is true above all of the law of contradiction. Contrary impulses exist side by side without cancelling each other out or diminishing each other: at the moment they may converge to form compromises under the dominating economic pressure towards the discharge of energy. [Q423, Freud, 1933, p. 73]
  • There is nothing in the id that could be compared with negation [i.e., a ‘no’]; and we perceive with surprise an exception to the philosophical theorem that space and time are necessary forms of our mental acts. There is nothing in the id that corresponds to the idea of time; there is o recognition of the passage of time, and – a thing that is most remarkable and awaits consideration in philosophical thought – no alteration in its mental processes is produced by the passage of time. Wishful impulses which have never passed beyond the id but impressions too which have been sunk into the id by repression, are virtually immortal; after the passage of decades they behave as though they had just occurred. They can only be recognised as belonging to the past, can only lose their importance and be deprived of the investment of energy, when they have been made conscious by the work of analysis. Again and again I have had the impression that we have made too little theoretical use of this fact, established beyond any doubt, of the inalterability by time of the repressed. [Q424, Freud, 1933, p. 74]
  • The id of course knows no judgement of value: no good and evil. [Q425, Freud, 1933, p. 74b]
  • It even seems that the energy of these impulses is in a state different from that in the other regions of the mind, far more mobile and capable of discharge. [Q426, Freud, 1933, p. 74c]
  • We can best arrive at the characteristics of the actual ego, in so far as it can be distinguished from the id and from the super-ego, by examining its relation to the outermost superficial portion of mental apparatus, which we describe as the perceptual system. This system is turned towards the external world, it is the medium for the perceptions arising thence, and during its functioning the phenomenon of consciousness arises in it. It is the sense-organ of the entire apparatus; moreover it is receptive not only to excitations from outside but also to those arising out of the interior of the mind. We need scarcely look for a justification of the view that the ego is that portion of the id which was modified by the proximity and influence of the external world, which is adapted for the reception of stimuli and as a protective shield against stimuli, comparable to the cortical layer by which a small piece of living substance is surrounded. The relation to the external world has become the decisive factor for the ego; it has taken on the task of representing the external world to the id. [Q427, Freud, 1933, p. 75]
  • The ego must observe the external world, must lay down an accurate picture of it on the memory traces of its perceptions, and by its exercise o the function of reality-testing, must put aside whatever in this picture of the external world is an addition derived from internal sources of excitation. The ego controls the approaches to motility under the id’s orders; but between a need and an action it has interposed a postponement in the form of the activity of thought, during which it makes use of the mnemic residues of experience. [Q428, Freud, 1933, p. 76]
  • The relation to time, which is so hard to describe, is also introduced into the ego by the perceptual system; it can scarcely be doubted that the mode of operation of that system is what provides the origin of the idea of time. But what distinguishes the ego from the id quite especially is a tendency to synthesis in its contents, to a combination and unification in its mental processes which are totally lacking in the id. When presently we come to deal with the impulses in mental life we shall, I hope, succeed in tracing this essential characteristic of the ego back to its source. It alone produces the high degree of organisation which the ego needs for its best achievements. The ego develops from perceiving the impulses to controlling them; but this last is only achieved by the representative of the impulses being allotted its proper place in a considerable assemblage, by its being taken up into a coherent context. To adopt a popular mode of speaking, we might say that the ego stands for reason and good sense while the id stands for the untamed passions. [Q429, Freud, 1933, p. 76]
  • The ego is after all only a portion of the id, a portion that has been expediently modified by the proximity of the external world with its threat of danger. [Q430, Freud, 1933, p. 77]
  • Thus, the ego, driven by the id, confined by the super-ego, repulsed by reality, struggles to master its economic task of bringing about harmony among the forces and influences working in and upon it; and we can understand how it is that so often we cannot suppress a cry: ‘Life is not easy!’ If the ego is obliged to admit its weakness, it breaks out in anxiety – realistic anxiety regarding the external world, moral anxiety regarding the super-ego and neurotic anxiety regarding the strength of the passions in the id. [Q431, Freud, 1933, p. 78]
  • The super-ego merges into the id; indeed, as heir to the Oedipus complex it has intimate relations with the id, it is more remote than the ego from the perceptual system. [Q432, Freud, 1933, p. 79]
  • It is easy to imagine too that certain mystical practices may succeed in upsetting the normal relations between the different regions of the mind, so that for instance, perception may be able to grasp happening in the depths of the ego and in the id which were otherwise inaccessible to it. [Q433, Freud, 1933, p. 80]
  • [The intention of psychoanalysis] is to strengthen the ego, to make it more independent of the super-ego, to widen its field of perception an enlarge its organisation, so that it can appropriate fresh portions of the id. Where id was, there ego shall be. It is a work of culture – not unlike the draining of the Zuider Zee. [Q434, Freud, 1933, p. 80b]
  • Thinking is an experimental action carried out with small amounts of energy. [Q435, Freud, 1933, p. 89]
  • The ego is the better organised part of the id, with its face turned towards reality. [Q436, Freud, 1933, p. 93]
  • An impulse then is distinguished from a stimulus by the fact that it arises from sources of stimulation within the body, that it operates as a constant force and that the subject cannot avoid it by flight, as is possible with an external stimulus. [Q437, Freud, 1933, p. 96]
  • The ego is always the main reservoir of libido from which libidinal investments of objects go out and into which they return again, while the major part of this libido remains permanently in the ego. Thus ego libido is constantly being changed into object libido and object libido into ego libido. [Q438, Freud, 1933, p. 103]

Standard Edition, Volume 23. Moses and Monotheism, An Outline of Psycho-Analysis and Other Works. 1937-1939.

  • The sexual life of human beings exhibits an efflorescence which comes to an end at about the firth year and it followed by what is known as the period of latency (till puberty)… [this] leads us to suppose that the human race is descended from a species of animal which reached sexual maturity in five years and rouses a suspicion that the postponement of sexual life and its diphasic onset are intimately connected with the history of hominisation. Human beings appear to be the only animal organisms with a latency period and sexual retardation of this kind. [Q439, Freud, 1939, p. 75]
  • We now distinguish in our mental life (which we regard as an apparatus compounded of several agencies, districts or provinces) one regions which we call the ego proper and another which we name the id. The id is the older of the two; the ego has developed out it, like a cortical layer, through the influence of the external world. It is in the id that all our primary impulses are at work, all the processes in the id take place unconsciously. [Q440, Freud, 1939, p. 96]
  • The psychical topography that I have developed here has nothing to do with the anatomy of the brain and actually only touches it at one point. What is unsatisfactory in this picture – and I am aware of it as clearly as anyone – is due to our complete ignorance of the dynamic nature of the mental processes. [Q441, Freud, 1939, p. 97]
  • But a fresh complication arises when we become aware of the probability that what may be operative in an individual’s psychical life may include not only what he has experienced himself but also things that were innately present in him at his birth, elements with a phylogenetic origin –an archaic heritage. [Q442, Freud, 1939, p. 98]
  • The immediate and most certain answer is that it consists in certain innate dispositions such as are characteristic of all living organisms: the capacity and tendency to enter particular lines of development and to react in a particular manner to certain excitations, impressions and stimuli. Since experience shows that there are distinctions in this respect between individuals of the human species, the archaic heritage must include these distinction; they represent what we recognise as the constitutional factor in the individual. [Q443, Freud, 1939, p. 98]
  • If any explanation at all is to be found of this instinctive life of animals, it can only be that they bring the experiences of their species with them into their own new existence – that is, that they have preserved memories of what was experienced by their ancestors. The position of the human animal would not at bottom be different… After this discussion I have no hesitation in declaring that men have always known (in this special way) that they once possessed a primal father and killed him. [Q444, Freud, 1939, p. 98b]
  • In our children, in adults who are neurotic, as well as in primitive peoples, we meet with the mental phenomenon which we describe as a belief in the ‘omnipotence of thoughts’. In our judgement this lies in an over-estimation of the influence which our mental acts can exercise in altering the external world. At bottom magic, the precursor of our technology, rests on this premise… The ‘omnipotence of thoughts’ was we suppose, an expression of the pride of mankind in the development of speech, which resulted in such an extraordinary advancement of intellectual activities. The new realm of intellectuality was opened up, in which ideas, memories, and inferences become decisive in contrast to the lower psychical activity which had direct perceptions by the sense-organs as its content. This was unquestionably one of the most important stages in the development of hominisation. [Q445, Freud, 1939, p. 113]
  • The oldest of these psychical provinces or agencies we give the name of id. It contains everything that is inherited, that is present at birth, that is laid down in the constitution – above all, therefore, the drives, which originate from the somatic organisation and which find a first psychical expression here in forms unknown to us. [Q446, Freud, 1940, p. 145]
  • Under the influence of the real external world around us, one portion of the id has undergone a special development. From what was originally a cortical layer, equipped with the organs for receiving stimuli and with arrangements for acting as a protective shield against stimuli, a special organisation has arisen which henceforth acts as an intermediary between the id and the external world. To this region of the mind we have given the name of ego. [Q447, Freud, 1940, p. 145b]
  • The ego has voluntary movement at its command. It has the task of self-preservation. As regards external events, it performs that task by becoming aware of stimuli, by storing up experiences about them (in the memory), by avoiding excessively strong stimuli (through flight), by dealing with moderate stimuli (through adaptation) and finally by learning to bring about expedient changes in the external world to its own advantage (through activity). As regards internal events, in relation to the id, it performs that task by gaining control over the demands of the drives, by devising whether they are to be allowed satisfaction, by postponing that satisfaction to times and circumstances favourable in the external world or by suppressing their excitation entirely. [Q448, Freud, 1940, p. 146]
  • The long period of childhood, during which the growing human being lives in dependence of his parents, leaves behind it as a precipitate the formation in his ego of a special agency in which this parental influence is prolonged. It has received the name of the super-ego. In so far as this super-ego is differentiated from the ego or is opposed to it, it constitutes a third power which the ego must take into account. [Q449, Freud, 1940, p. 146b]
  • The id and the super-ego have one thing in common: they both represent the influence of the past – the id the influence of heredity, the super-ego the influence , essentially of what is taken over from other people – whereas the ego is principally determined by the individual’s own experience, that is by accidental and contemporary events. [Q450, Freud, 1940, p. 147]
  • This general schematic picture of a psychical apparatus may be supposed to apply as well to the higher animals which resemble man mentally. A super-ego must be presumed to be present wherever, as is the case with man, there is a long period of dependence in childhood. [Q451, Freud, 1940, p. 147b]
  • The power of the id expresses the true purpose of the individual organism’s life. This consists in the satisfaction of its innate needs. No such purpose as that of keeping itself alive or of protecting itself from dangers by means of anxiety can be attributed to the id. That is the task of the ego. [Q452, Freud, 1940, p. 148]
  • The forces which we assume to exist behind the tensions caused by the needs of the id are called the drives. They represent the somatic demands upon the mind. [Q453, Freud, 1940, p. 148]
  • It is hard to say anything of the behaviour of the libido in the id and the super-ego. All that we know about it relates to the ego, in which at first the whole available quota of libido is stored up. We call this state absolute, primary narcissism. It lasts till the ego begins to invest the ideas of objects with libido, to transform narcissistic libido into object-libido. Throughout the whole of life the ego remains the great reservoir from which libidinal investments are sent out to objects and into which they are also once more withdrawn. [Q454, Freud, 1940, p. 150]
  • What come about in analytic treatment as a result of our efforts can also occur spontaneously: material which is ordinarily unconscious can transform itself into preconscious [i.e., consciously accessible] material and then become conscious – a thing that happens to a large extent in psychotic states. From this we infer that the maintenance of certain internal resistances is a sine qua non of normality. [Q455, Freud, 1940, p. 161]
  • The process of something becoming conscious is above all linked with the perceptions which our sense organs receive from the external world. From the topographical point of view, therefore, it is a phenomenon which take place in the outermost cortex of the ego. [Q456, Freud, 1940, p. 161b]
  • Internal processes in the ego may also acquire consciousness. This is the work of the function of speech which brings material in the ego into a firm connection with mnemic residues of visual but more particularly auditory perceptions. Thenceforward the perceptual periphery of the cortical layer can be excited to a much greater extent from inside as well, internal events such as passages of ideas and thought-processes can become conscious and a special device is called for in order to distinguish between the two possibilities – a device known as reality-testing. [Q457, Freud, 1940, p. 162]
  • The sole prevailing quality in the id is that of being unconscious. Id and unconscious are as intimately linked as ego and preconscious. [Q458, Freud, 1940, p. 163]
  • Originally, to be sure, everything was id; the ego was developed out of the id by the continual influence of the external world. In the course of this slow development certain of the contents of the id were transformed into the preconscious state and so taken into the ego, others of its contents remained in the id unchanged, as its scarcely accessible nucleus. [Q459, Freud, 1940, p. 163b]
  • During this development, however, the young and feeble ego put back into the unconscious state some of the material it has already taken in, dropped it and behaved in the same way to some fresh impressions which it might have taken in, so that these, having been rejected, could leave a trace only in the id. In consideration of its origin we speak of this latter portion of the id as the repressed. [Q460, Freud, 1940, p. 163c]
  • We seem to recognise that nervous or psychical energy occurs in two forms, one freely mobile and another, by comparison, bound; we speak of activations] and [hyperactivations] of psychical material, and even venture to suppose a [hyperactivation] brings about a kind of synthesis of different processes – a synthesis in the course of which free energy is transformed into bound energy… We hold firmly to the view that the distinction between the [primary] and the [secondary] state lies in dynamic relations of this kind, which would explain how it is that, whether spontaneously or with our assistance, the one can be changed into the other… We have found that processes in the unconscious or in the id obey different laws from those in the ego. We name these laws in their totality the primary process, in contrast to the secondary process which governs the course of events in the ego.”[Q461, Freud, 1940, p. 164]
  • An investigation of normal, stable states, in which the frontiers of the ego are safeguarded against the id… would teach us little. The only thing that can help us are states of conflict and uproar, where the contents of the unconscious id have a prospect of forcing their way into the ego and into consciousness… It is only under these conditions that we can make such observations as will confirm or correct our statements about the two partners [Q462, Freud, 1940, p. 165]
  • Now our nightly sleep is precisely a state of this sort, and for that reason psychical activity during sleep, which we perceive as dreams, is our most favourable object of study. [Q463, Freud, 1940, p. 165b]
  • The study of the dream-work teaches us by an excellent example the way in which unconscious material from the id (originally unconscious and repressed unconscious alike) forces its way into the ego. [Q464, Freud, 1940, 165c]
  • Dreams bring up recollections which the dreamer has forgotten, which are inaccessible to him when he is awake. [Q465, Freud, 1940, p. 166]
  • Since the waking ego governs motility, that function is paralysed in sleep, and accordingly a good part of the inhibitions imposed on the unconscious id become superfluous. The withdrawal or reduction of these [inhibitory forces] thus allow the id what is now a harmless amount of liberty. [Q466, Freud, 1940, p. 166b]
  • Memory very often reproduces in dreams impressions from the dreamer’s early childhood. [Q467, Freud, 1940, p. 166c]
  • Dreams bring to light material which cannot have originated either from the dreamer’s adult life or from his forgotten childhood. We are obliged to regard it as part of the archaic heritage which a child brings with him into the world, before any experience of his own, influenced by the experience of his ancestors. We find the counterpart of this phylogenetic material in the earliest human legends and in surviving customs. Thus dreams constitute a source of human prehistory which is not to be despised. [Q468, Freud, 1940, p. 167]
  • But what makes dreams so invaluable in giving us insight is the circumstance that, when the unconscious material makes its way into the ego, it brings its own modes of working along with it. [Q469, Freud, 1940, p. 167b]
  • Our theory infers that in the unconscious id the energy is in a freely mobile state and that the id sets more store by the possibility of discharging quantities of excitation than by any other consideration; and our theory makes use of these two peculiarities in defining the character of the primary process we have attributed to the id. [Q470, Freud, 1940, p. 168]
  • The governing rules of logic carry no weight in the unconscious; it might be referred to as the Realm of the Illogical. Urges with contrary aims exist side by side in the unconscious without any need arising for an adjustment between them. [Q471, Freud, 1940, p. 168-169]
  • Something that is a satisfaction for the unconscious id may for that very reason be a cause of anxiety for the ego. [Q472, Freud, 1940, p. 171]
  • Experience has shown that the unconscious mechanisms which we have come to know from our study of the dream-work and which gave us the explanation of the formation of dreams also help us to understand the puzzling symptoms which attract our interest to neuroses and psychoses. [Q473, Freud, 1940, p. 171b]
  • A dream, then, is a psychosis, with all the absurdities, delusions and illusions of a psychosis. [Q474, Freud, 1940, p. 172]
  • The necessary precondition of the pathological states under discussion can only be a relative or absolute weakening of the ego which makes the fulfilment of its tasks impossible. The severest demand on the ego is probably the keeping down of the impulsive claims of the id, to accomplish which it is obliged to maintain large expenditures of energy on [inhibition]. [Q475, Freud, 1940, p. 172b]
  • We may suspect that in the economic conflicts which arise at this point, the id and the super-ego often make common cause against the hard-pressed ego which tries to cling to reality in order to retain its normal state. If the other two become too strong, they succeed in loosening and altering the ego’s organisation so that its proper relation to reality is disturbed or even brought to an end. We have seen it happen in dreaming: when the ego is detached from the reality of the external world, it slips down under the influence of the internal world into psychosis. [Q476, Freud, 1940, p. 172-173]
  • The [unconscious] has a natural upward drive and desires nothing better than to press forward across its settled frontiers into the ego and so to consciousness. [Q477, Freud, 1940, p. 179]
  • But here we are concerned with therapy only in so far as it works by psychological means; and for the time being we have no other. The future may teach us to exercise a direct influence, by means of particular chemical substances, on the amounts of energy and their distribution in the mental apparatus. It may be that there are other still undreamt-of possibilities of therapy. But for the moment we have nothing better at our disposal than the technique of psycho-analysis, and for that reason, in spite of its limitations, it should not be despised. [Q478, Freud, 1940, p. 180]
  • The core of our being, then, is formed by the obscure id, which has no direct communication with the external world and is accessible even to our own knowledge only through the medium of another agency. Within the id the organic drives [Q479, Freud, 1940, p. 197]
  • But immediate and unheeding satisfaction of the drives such as the id demands would often lead to perilous conflicts with the external world and to extinction. The id knows no solicitude about ensuring survival and no anxiety; or it would perhaps be more correct to say that, though it can generate the sensory elements of anxiety, it cannot make use of them. The processes which are possible in and between the assumed psychical elements in the id (the primary process) differ widely from those which are familiar to us through conscious perception in our intellectual and emotional life; nor are they subject to the critical restrictions of logic, which repudiates some of these processes as invalid and seeks to under them. [Q480, Freud, 1940, p. 198]
  • The ego has been developed out of the id’s cortical layer, which through being adapted to the reception and exclusion of stimuli, is in direct contact with the external world (reality). Starting from conscious perception is has subjected to its influence ever larger regions and deeper strata of the id. [Q481, Freud, 1940, p. 198-199]
  • The ego makes use of sensations of anxiety as a signal to give warning of dangers that threaten its integrity. Since memory traces can become conscious just as perceptions do, especially through association with residues of speech, the possibility arises of a confusion which would lead to a mistaking of reality. The ego guards itself against this possibility by the institution of reality-testing, which is allowed to fall into abeyance in dreams. [Q482, Freud, 1940, p. 199b]
  • [The ego’s] psychological function consists in raising the passage of [energy] in the id to a higher dynamic level (perhaps by transforming freely mobile energy into bound energy). [Q483, Freud, 1940, p. 199c]
  • Thus the ego is fighting on two fronts: it has to defend against an external world which threatens it with annihilation as well as against an internal world that makes excessive demands. [Q484, Freud, 1940, p. 200]
  • The ego owes its origin as well as the most important of its acquired characteristics to its relation to the real external world. We are thus prepared to assume that the ego’s pathological states, in which it most approximates once again to the id, are founded on a cessation or slackening of the relation to the external world… The precipitating cause of an outbreak of psychosis is either that reality has become intolerably painful or that the drives have become extraordinarily intensified – both of which, in view of the rival claims on the ego made by the id and the external world, must lead to the same result. The problem of psychoses would be simple and perspicuous if the ego’s detachment from reality could be carried through completely. But that seems to happen rarely or perhaps never. Even is a state so far removed from the reality of the external world as one of hallucinatory confusion, one learns from patients after their recovery that at the time in some corner of their mind (as they put it) there was a normal person hidden, who, like a detached spectator, watched the hubbub of illness go past him. [Q485, Freud, 1940, p. 201]
  • At about [the age of five] an important change [takes place in the ego]. A portion of the external world has, at least partially, been abandoned as an object and has instead, by identification, been taken into the ego and this become an integral part of the internal world. This new psychical agency continues to carry on the functions which have hitherto been performed by the people in the external world: it observes the ego, gives it orders, judges it and threatens it with punishments, exactly like the parents whose place it has taken. [Q486, Freud, 1940, p. 205]
  • The super-ego continues to play the part of the external world for the ego, although it has become a portion of the internal world. [Q487, Freud, 1940, p. 206]
  • Twice in the course of individual development certain drives are considerably reinforced: at puberty, and, in women, at the menopause. We are not in the least surprised if a person who was not neurotic before becomes so at these times. [Q488, Freud, 1940, p. 226]
  • The repressions behave like dams against the pressure of water. [Q489, Freud, 1940, p. 226]
  • Repressions depend absolutely and entirely on the relative strength of the forces involved and they cannot hold out against an increase in the strength of the drives. [Q489, Freud, 1940, p. 227]
  • When we speak of an ‘archaic heritage’, we are usually thinking only of the id. [Q490, Freud, 1940, p. 240]
  • In certain analyses… [patients] have had lively recollections called up in them – which they themselves have described as ‘ultra-clear’. [Q491, Freud, 1937, p. 266]
  • The transposing of material from a forgotten past on to the present or on to an expectation of the future in indeed a habitual occurrence in neurotics no less than psychotics. Often enough, when a neurotic is led by an anxiety-state to expect the occurrence of some terrible event, he is in fact merely under the influence of a repressed memory (which is seeking to enter consciousness but cannot become conscious) that something which was at the time terrifying did really happen. I believe that we should gain a great deal of valuable knowledge from work of this kind upon psychotics even if it led to no therapeutic success. [Q492, Freud, 1937, p. 268]
  • In consequence of the special character of our discoveries, our scientific work in psychology will consist in translating unconscious processes into conscious ones, and thus filling the gaps in conscious perception. [Q493, Freud, 1940b, p. 286]

Note: with regards our use of terms, for accessibility we have chosen to refer to the problematic German term “besetzung” (“filling” in English but referred to as “cathexis” in the standard edition) as “activated”, “activation”, “activity”, “investment” and in some cases simply “energy” – also “anticathexis” is translated as “inhibition” or “inhibitory action”. Our rationale for this is to simplify the terms and make them more accessible, especially to those who might be put-off by overly-complicated neologisms which were not Freud’s own. Similarly, we have chosen to use the term “ego” instead of “preconscious”. The motivation for this again is to improve the reader’s familiarity with the system being described. For the same reasons we also sometimes refer to “the unconscious” or “system Ucs” as “the id” and we refer to “instinct” as “drive” or “impulse” which are arguably truer translations of the German “triebe”. Finally, we refer to the “system Cs (Pcpt)” with the simpler “perceptual system” and relate this to the DMN’s anticorrelated networks; principally, the attention and salience systems.

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