Perception

When a real object causes an image of itself to form on each of the retinas of our eyes, the image is upside down. It used to be thought that there was a 180 degree twist in the optic nerve to turn it right side up again, but then it was found that there is no such twist. So now it is believed that the image is reoriented in the unconscious mind. Does it not follow that when we see something, we see a twice inverted image of the real object, not the real object itself?

Comments

Questions along this line have been asked a few times before: See, for example, 987 and 988. The answer is that, no, it does not follow: You see the object. That there is an inverted image of the object on your retina is part of how you see the object. You do not see that image. I could see that image, if I looked in your eye, and I suppose you could see it, too, if you looked in a mirror or something. But with what precisely would you see it in the ordinary course of events?

The idea that the retinal image has to be "re-oriented" is really quite puzzling and probably a product of the same kind of mistake. To think the image needs to be reoriented is, it seems to me, to suppose that the spatial properties of the representation must be spatial properties of what is represented. There is simply no reason to assume that. If you turn a map sitting on the table around so I can see it, thus changing the spatial properties of the representation, the map does not suddenly represent everything as having been turned 180 degress. It continues to represent precisely what it did before. Similarly, that the image on the retina is, qua representation, inverted wtih respect to what it represents does not imply that it represents everything as being upside down. And if there is something like an image in the visual cortex—of course, it would not be an image in the straightforward sense, since it would not be something one could see—there is no reason it needs to be spatially oriented the same way as what it represents. It too might be upside down, or sideways, or whatever, and that would be quite irrelevant to what it represents.

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