Tradeoffs between stereopsis and proximity luminance covariance as determinants of perceived 3D structure.

A 2D polar projection of a 3D wire cube (Necker cube) in clockwise rotation can be perceived either veridically as a clockwise-rotating cube (rigid percept) or as a counterclockwise-rotating rubbery, truncated pyramid (nonrigid percept). The 3D percept is influenced by various cues: linear perspective, stereo disparity, and proximity-luminance covariance (PLC, the intensification of edges in proportion to their proximity to the observer). Perspective, by itself or in combination, is a very weak cue whereas PLC is a powerful cue [Schwartz and Sperling (1983) Bull. Psychon. Soc. 21, 456-458]. Here we determined psychometric functions for perceptual resolution in static displays and dynamic rotating displays (with and without a static preview) as determined by stereopsis and PLC in isolation and with both cues jointly, possibly in conflict. Stereopsis was the dominant cue in static displays and in most dynamic displays. When a static display preceded a dynamic display, it strongly influenced the subsequent dynamic percept. Perceptual resolution in all conditions was accurately described by a winner-take-all model in which the strength of evidence for each percept from different cues is simply algebraically added.