Apparent Motion of the Human Body

Observers viewed pairs of alternating photographs of a human body in different positions. Shortest-path motion solutions were pitted against anatomically possible movements. With short stimulus onset asynchronies (SOAs), observers tended to report the shortest path despite violations of anatomical constraints. However, with longer SOAs observers became increasingly likely to report the anatomically possible, but longer, paths. This finding, in conjunction with those from a second study, challenges the accepted wisdom that apparent motion paths are independent of the object. Instead, our findings suggest that when given enough time and appropriate stimuli, the visual system prefers at least some object-appropriate apparent motion paths.