Monday, November 29, 2010

Gregory: The Visual System is Part Camera, Part Not-Camera

As I noted in comments to a previous post, Gregory's Eye and Brain seems to me to be a nice corrective to some of the caricatures of cognitivism.  It is a nice work on vision for a general audience.

The eye is a simple optical instrument. With internal images projected from objects in the outside world, it is Plato's cave with a lens. The brain is the engine of understanding. There is nothing closer to our intimate experiences, yet the brain is less understood and more mysterious than a distant star. 
Optical images were unknown before the tenth century, and not until the start of the seventeenth were images discovered in eyes. At last it became clear that light does not enter or leave the brain, locked privily in its box of bone. All the brain receives are minute electrochemical pulses of various frequencies, as signals from the senses. The signals must be read by rules and knowledge to make sense. Yet what we see, and what we know, or believe, can be very different. As science advances, differences between perceived appearances and accepted realities become ever greater.
     This is far beyond the common account that the eye is a camera; yet this is essentially true, though far from the whole story. It is the uncamera-like features of eyes and brains that most interest us here.  (Gregory, 1997, pp. 1-2).
When I read Gregory on this kind of thing, I take his critical target to be the views of scientists and philosophers from centuries ago.  With EP, I generally think that the critical targets are much closer to home, e.g. Gregory.

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