Thus, we may conclude that von Helmholtz, Julesz, Pettigrew and Ramachandran are all right; the visual processing of stereo is more complex than we thought. We have no inkling of the physiological mechanisms underlying these interactions. Cells signaling disparity are in V1 (as shown by Pettigrew), but cells that extract illusory contours (from implied occlusion) are extracted in area V2, the next stage up, as shown by Rudiger von der Heydt of Johns Hopkins University. These findings imply that messages from V2 must be fed back to V1 to modulate processing of smaller features. This idea has yet to be tested.
Note: This article was originally printed with the title, "Two Eyes, Two Views."
This article was originally published with the title Two Eyes, Two Views.
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3 Comments
Add CommentThankyou for a very informative article, which deals with vision rather than perception. The brain is aware of what is behind it, even if we are not looking there. In the same way blind people have mental images of what is around them. Similarly we know how objects are moving when we hear them. The brain has to combine this and all other sensory stimuli into one concious image extending sometimes for miles around us and memorise it all as we move! Stereo vision is only one small part of perception...
Reply | Report Abuse | Link to thisI think that peripheral vision has a lot to do with our perception of depth, and dimension. The ability to "see" up, down, to the sides and forward all at once is the true mechanism of sight. This article would be very on target if it was "focus" at it's crux.
Reply | Report Abuse | Link to thisVery interesting. I've had little sight; am able to see light or darkness, but can not focus in my right eye since I was a little tyke. So, don't know how this affects my brain.
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