Dynamic occlusion in the perception of rotation in depth.

Abstract

Occlusion of more distant texture elements by nearer elements can provide relative distance information in parallel projections of rotating objects, according to Braunstein, Andersen, and Riefer (1982). In that study, occlusion was present in static views in the form of contour interruptions or interposition. In the present study, all visible contours were eliminated. Dots were located within implicit pentagonal texture elements on a transparent sphere. The proportion of the sphere’s surface covered by pentagons and dot density within the pentagons was varied. Accuracy of direction of rotation judgments was significantly affected by area, but not by dot density. Accuracy levels with purely kinetic occlusion were as high as in the earlier study, which included static interposition. Judgments of depth and shape were not affected significantly by occlusion, suggesting that occlusion is a specialized source of information for depth order. Levels of texture and the separability of depth and relative distance judgments are discussed.