抄録
The polarity of depth specified by binocular disparity or motion parallax is sometimes perceived opposite to that of the geometrical prediction. Previous studies have suggested that apparent shape distortion induced by these depth cues contributes to depth reversal. We tested this suggestion by examining the relationship between apparent depth and shape distortion. Disparity or motion parallax gradient was introduced into a grid pattern subtending 20 deg of visual field so that a slanted flat surface or concave/ convex surface was perceived. Observers judged the directions of apparent depth and shape distortion using a two-alternative forced choice method. When the apparent depth was reversed, some observers perceived a veridical shape while others perceived a reversed one. The former is consistent with the prediction of the theory that hypothesizes the contribution of apparent shape distortion as a perspective depth cue; however, the latter can not be explained by the theory. This suggests that the sign of binocular disparity or motion parallax can itself be reversed at a relatively early stage of depth information processing.
