Static depth cues do affect the perceived direction of motion.
Models of motion perception usually assume that the visual system references spatial displacements to retinal coordinates, and not to three-dimensional coordinates recovered by a parallel process. The present studies investigated whether moving elements viewed in the context of a static random-dot stereogram could lead to the appearance of motion in depth. Observers judged the velocity of a monocular element translating horizontally in the stereo context as 'same as' or 'different to' that of a standard. Based on velocity constancy, if there was apparent motion in depth, the relative velocity judgments would yield a predictable pattern of errors. The first experiment compared two stereo contexts: a sloped surface versus a fronto-parallel plane at zero disparity. The results indicated an overall increase in the perceived velocity of the element moving in the sloped surface context. A similar pattern of results was found when surfaces differing in incline were compared. Experiment 2 explored the case of fronto-parallel planes at crossed and uncrossed disparities. Here depth differences did not systematically affect observers' judgments. It was concluded that in some cases motion analysis can be affected by three-dimensional disparity information and not by angular displacement alone.
Mowafy
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Department of Psychology, Vanderbilt University, Nashville, TN 37240.
D000054:Acceleration; D000328:Adult; D001288:Attention; D003463:Cues; D003867:Depth Perception; D004193:Discrimination Learning; D005260:Female; D006801:Humans; D008297:Male; D009039:Motion Perception; D009903:Optical Illusions; D009949:Orientation; D010364:Pattern Recognition, Visual; D010470:Perceptual Masking; D011601:Psychophysics