Alva Noe against Hubel and Wiesel

Alva Noe appears to be really irritated that David Hubel and Torsten Wiesel won the 1981 Nobel prize for physiology, for their work on the information processing in the visual system of mammals. He directs a whole chapter of ‘Out of Heads (Why You Are Not Your Brain, and Other Lessons from the Biology of Consciousness)’ against them.

The charges against them might be stated as:

  • main charge: an instance of biologists betraying their cause and taking a ‘physicist’ i.e. reductionist approach to a problem, rather than a biological i.e. systems approach.
  • Their unthinking assumption that vision can even be considered a computational process.
  • Their interpretation of the visual system as having an hierarchical organization – as if designed.
  • That particular cells perform (single) particular functions e.g. edge-detection.
  • The experiments were [mercifully] conducted when the animals were anaesthetized, thus not done when the animals were actually seeing and interacting with the world.

My figure below means to show:

  • Hubel and Wiesel’s layered (hierarchical) structure of the visual processing: as processing passes through various stages (3-(5).
  • The feedback processing (7)-(9) and connections (11)-(15), assuming the visual system can indeed be structured into such a hierarchical fashion.
  • Noe’s notion of mind leaking out of our heads, with further loops formed with excursion outside of our heads, by our motor system (16)-(19) causing interaction with the world, and feeding back (21) into our senses (2).

An interesting point of fact from Noe: there are many more feedback connections (7)-(9) than there are forward connections (3)-(5) (see my previous blog posting 2011/02/06 ).

We may naively say that when the animals are anaesthetized, the visual processing is operating in an open-loop manner from (2) to (6), with minimal feedback from the (unconscious) ‘mini-me’ (6). Thus the reported behaviour of the visual system falls so very far short of the real behaviour when the animal is awake.

I have some sympathies for Hubel and Wiesel – when you know virtually nothing about something, speculating at systems level will get you nowhere. Reductionism works! Find out something about the subject of investigation using whatever flawed, incomplete approaches you can. What you discover is almost certainly wrong but it’s the best way of advancing onto something better.

Visual Processing Loops

BTW: Noe is only concerned with the science of Hubel and Wiesel and makes no mention of the fact that you can still win a Nobel Prize by maltreating animals. Some ethical charges against Hubel and Wiesel, drawn merely from what Noe incidentally refers to:

  • sensory deprivation of cats by rearing them in the dark
  • sensory deprivation of cats and monkeys by sewing their eyelids shut
  • (the poking of electrodes into the visual cortices of cats and monkeys was whilst they were anaesthetized, so that doesn’t count).
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