Abstract

Certain intensity relations between neighboring regions permit the viewer to perceive transparent surfaces in a particular depth order. We explored how this transparent layering cue interacts with binocular disparity to determine whether two superimposed moving gratings appear as independently moving surfaces (component motion) or as a single plaid surface moving in a unified direction (pattern motion). Subjects stereoscopically viewed moving plaid stimuli comprised of asymmetric squarewave gratings. The narrow bars of the two gratings had different luminances, 0.8 and 78 cd/m², whereas the intersecting regions had luminance 37 cd/m², causing the lighter grating to appear transparent and in front of the darker grating. Disparity was manipulated to provide a depth cue that was either consistent or inconsistent with the perceived transparent layering. When both cues supported the same depth relation, only small disparity differences were required for the gratings to appear as separately moving surfaces. Conversely, when the two cues were inconsistent, much greater disparities were required. Other experiments concerning depth estimates to nonmoving stimuli suggest that perceived transparent layering and disparity cues combine to determine an estimate of depth. These results indicate that the coherence of moving plaid stimuli is determined by consistent surface interpretations emerging from the integration of information concerning motion, disparity, and intensity relations.

© 1991 Optical Society of America