Abstract
Although the binocular vertical size disparity causes the slant perception around a vertical axis (induced effect), it is not clear how human adapts to vertical size disparity. We examined the time course of adaptation to the vertical size disparity caused by wearing the cylinder lens for the astigmatism correction. The results showed that the two-dimensional distortion in monocular viewing and the three-dimensional slant perception caused by "induced effect" in binocular viewing were occurred for two days from wearing the cylinder lens but not all the days that follow. On the other hand, the cylinder lens causes the rapid decline in the feelings. Eventually, it took about two weeks to remove the uncomfortable feeling.
