SPATIAL LIMITATION OF VERTICAL-SIZE DISPARITY PROCESSING

We investigated the upper limit of horizontal spatial modulation of ve rtical-size disparity in a textured surface for the perception of dept h. In Experiment 1 subjects matched the appearance of a surface with m odulated horizontal-size disparity to that of a surface with modulated vertical-size disparity. In Experiment 2 we determined the threshold amplitude of modulation of vertical-size disparity required for the pe rception of depth as a function of the spatial frequency of disparity modulation. The results indicate that sensations of depth are not elic ited by modulations of vertical-size disparity of any amplitude at spa tial frequencies higher than about 0.04 c/deg, We conclude that vertic al disparities are averaged within about 20 deg-wide areas and suggest that this global measurement is used to scale local horizontal dispar ities for the perception of surface slant. (C) 1997 Elsevier Science L td.