Low-level and high-level processes in the perceptual organization of three-dimensional apparent motion

An experiment is described in which a bistable motion display is shown in four combinations of monoptic and dichoptic viewing. When two triangles are replaced by one of them, one of two competing phenomena can be seen: local disappearance of the triangle that has not been replaced; a 3-D rotation of a rigid triangle from one location to another. The dependence of the first sensation on the duration of the interstimulus interval and on monocular availability of the local-identity information confirms previous evidence about the existence of two processes which mediate apparent motion. The localization of the high-level process, however, is questioned on the basis of a comparison of data obtained when motion information was monoptic or only dichoptic. As monoptic motion information seems more effective, the 'figural' higher process cannot be wholly located at the binocular level.