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Vision is a 'Reflex'
kernkopje writes "A recently publicized book by two neurobiologists at Duke University introduces an interesting emperical theory on vision. Rather than postulating a visual system that generates a picture of what actually exists in front of the viewer, they theorize that evolution, as well as life experience, has created a visual system in which perceptions represent what a given visual stimulus has typically signified in the past. Admiring the view from a high building, staring at a beautiful woman, shapes, colors, textures, it's basically all the same knee-jerk response...
The news release is here, read more about the concept here. Their lab work & results can be found here."
Took that story long enough to wind up on slashdot.
I could have told them that what you perceive as being there is based on your previous experience as opposed to what is actually there. The data from your eyes is just far too noisy, and my brain has guessed wrong often enough that its become obvious that what I was seeing was based on previous experience. By the way, hearing works the same way. Calling it a reflex, however doesn't seem right.
Yes, illusions occur at the level of perception. The researchers in the article even speak briefly about the currently accepted theories on visual neurobiology involving the retinas, nerve cells, etc. The current theories even explain some of the types of visual illusions that people fall into. However, what is novel here is that the researchers have isolated certain types of visual illusions that current theories can't readily explain, and the researches have come up with a theory that *can* account for these specific types of visual illusions, as well as all the others, *and* their theories _may_ prove to be generalizable to the other sense perceptions occuring in the cerebral cortex. In no way is this banal observation.
The reason why the brain confuses colors and such is because it quite sensibly corrects for shadows. It very sophisticatedly determines the light source, and compensates for it. Why is that so hard to grasp?
This seems partly their point. Millions of years of evolution and decades of personal development lead to this sophisticated compensation mechanism. Which makes assumptions which turn out to incorrect, and can be fooled. The light hitting the eye is ambiguous, the brain applies assumptions that in the past worked, but fails when exposed to illusions of this sort.