ANISOTROPY IN WERNERS BINOCULAR DEPTH-CONTRAST EFFECT

We investigated Werner's binocular depth-contrast effect. Subjects vie wed stereograms consisting of a test pattern and an inducing pattern. The half-images of the inducing pattern were either horizontally scale d or sheared relative to each other. Subjects judged the (induced) per ceived slant of the test pattern. We were interested in what influence the spatial configuration of the test pattern and the inducing patter n had on the depth-contrast effect. We conclude that the depth-contras t effect is a global effect. In other words, it is not restricted to t he location of the inducing pattern. The effect decreases with distanc e, however, in an anisotropic way. The depth-contrast effect was prese nt most prominently when the test pattern was positioned in the direct ion along the slant (rotation) axis of the inducing pattern. We sugges t that Werner's depth-contrast effect can be explained by the (previou sly reported) findings that: (1) stereopsis is relatively insensitive to whole-field horizontal scale and shear; and (2) stereopsis is very sensitive to horizontal scale and shear of two stimuli relative to eac h other. Copyright (C) 1996 Elsevier Science Ltd.