Mirrors reverse our image only left and right. Why not up and down?

Friar Tuck

Friar Tuck says: If you had your eyes one above the other, it would. The image you see is in fact reversed both ways but the brain compensates for the vertical. This has been tested by scientists who have given people glasses that flip the image vertically. After a period the brain readjusts and turns it back again. When the glasses are removed the person sees the image reversed and the brain has to readjust once more. Wed Feb 20 19:58:00 CST 2002 (To fix typo - McG) May 25 03, 1:03 PM

Gnomon

Gnomon says: Mirrors do not in fact reverse things left to right, they reverse them front to back. If you look at the image in the mirror, its top, bottom, left and right are all in the same position as you. Its front and back are the opposite to you. You compensate for this by mentally turning the image in the mirror around a vertical axis, because that's the way that people turn. If the image were turned in this way, then the left and right would be reversed. To make this clearer, imagine you standing still but your image in the mirror turning around so that it had its back to you. It would turn keeping its head at the top and feet at the bottom, so instead of being front/back reversed, it would be left/right reversed. Now imagine that your image is a circus gymnast. Instead of turning around in the normal way, it turns by standing on its head, so that now it has its back to you, but its head is at the bottom, its feet are at the top and left and right are unchanged. The image is now top/bottom reversed. So you see that the real reflection is front/back reversed. We think of this as left/right reversed because of our own vertical symmetry and our tendency to turn backwards by rotating around a vertical axis. Wed Feb 20 21:13:04 CST 2002 (To fix typo - McG) May 25 03, 1:05 PM