Many years ago my theoretical physicist crony Nick Herbert sent me a clipping from Fortune magazine that reproduced the picture above. Knowing that it would needle me, Herbert wrote on the clipping the words "seeing is believing" with reference to the caption that claims that "visual images [are] transported intact to the brain." The picture was reproduced from an article that had then recently appeared in Science magazine by Russell DeValois and his research team at UC Berkeley. It shows both the pattern the monkey looked at and the corresponding "image" of it in the monkey cortex.
"What's wrong with this picture," as the expression goes?
How about this answer to your Q?
ReplyDeleteThis experiment does not relate to any visual image (in the commonly used sense of that term in psychophysics) but to neuronal activity, that may be the NCCs of visual images (sensations) but are not the images themselves. So images cannot said to be "transported from the retina to the cortex.
In the context of vision science the word "image" is really only used in one way: the "retinal image," which can actually be seen and has been photographed. VS is not called an "image." The visual projection areas in the cortex are not called "images" but are now most commonly called "maps" (leaving aside the question of who it is inside the brain that looks at those maps, and to what purpose). Sometimes they are called "neural representations," but today at least one does not encounter the word "image" in this connection. The idea that images are "transmitted" to the brain is a left over from the pages of "Popular Science."
ReplyDeleteFancy that Russell De Valois himself proposed that the visual cortex was performing a spatial frequency analysis on "input" from the eyes, and was thus decidedly not involved in creating anything like an image, but could be said to be decomposing the pattern of retinal image, if anything.
So ostensibly "Fortune" magazine just engaged in scientific "hype," implying by its language that by showing these "images" more had really been discovered about the nature of visual perception than had been (almost 30 years ago now). This is therefore a good example of what opponents to psychoneural identity theory call "promissory materialism," in this case coming from overstated claims and findings that leave fundamental theoretical questions unanswered, but with "promises" of major breakthroughs being made all the same.