What learning to see arbitrary motion tells us about biological motion perception

In separate studies, observers viewed upright biological motion, inverted biological motion, or arbitrary motion created from systematically randomizing the positions of point-light dots. Results showed that observers (a) could learn to detect the presence of arbitrary motion, (b) could not learn to discriminate the coherence of arbitrary motion, although they could do so for upright biological motion, (c) could apply a detection strategy to learn to detect the presence of inverted biological motion nearly as well as they detected upright biological motion, and (d) performed better discriminating the coherence of upright biological motion compared with inverted biological motion. These results suggest that learning and form information play an important role in perceiving biological motion, although this role may only be apparent in tasks that require processing information from multiple parts of the motion display.