Perception of biological motion as motion-from-form

Abstract

The recognition of the movements and ac­tions of others is of great importance for social interaction. The visual motion pat­tern projected on the retina when watching somebody else act is called biological mo­tion. Because of the many degrees of free­dom of the body, biological motion is a rel­atively complicated motion pattern, much more variable, for example, than optic flow or object motion. The regularities of biolog­ical motion are contained in its relationship to the body, i.e. in the constraints imposed by the articulation of the limbs on the move­ment of the body parts. The neural mecha­nisms of biological motion perception, there­fore, take body form information into ac­count. I describe a model of biological mo­tion perception that starts from a representa­tion of body form and posture and retrieves biological motion as the transformation of the body posture over time. Essentially, this proposes a ventral pathway to motion per­ception that is distinct from the other motion pathways in the dorsal stream, and special­ized for body motion.