Spatial displacement limits for cyclopean (stereoscopic) apparent-motion perception

The range of spatial displacements over which cyclopean (stereoscopic) apparent motion is perceived was investigated. The cyclopean stimuli were created from retinal disparity embedded in dynamic random-dot stereograms. In one experiment, the displacement range for crossed-disparity cyclopean motion was compared with that for luminance-domain motion. The results showed that cyclopean motion was perceived over spatial displacements that were about two to three times larger than the displacements over which luminance motion was perceived. In a second experiment, the displacement range for crossed-disparity cyclopean motion was compared with that for uncrossed-disparity cyclopean motion. The results revealed that the displacement range was restricted (motion quality was poor) for uncrossed motion relative to crossed motion. It is inferred that cyclopean motion from crossed disparity is represented at a coarse spatial scale, relative to luminance motion, and that cyclopean motion from uncrossed disparity is suppressed due to occlusion cues present when uncrossed stimuli are seen behind a textured background.