Mechanisms for Motion Perception

Edward H. Adelson

Published in
Optics & Photonics News, August, pp. 24-30 (1991).
Motion perception can occur with a variety of stimuli, and there may be several different mechanisms involved in motion analysis. The simplest sort of motion stimulation can be considered to involve patterns that are oriented in space-time, and which possess local "motion energy." The simplest motion mechanisms are those that respond to the motion energy in the stimulus. Many phenomena in human motion perception can be explained in terms of these mechanisms, including the apparent motion seen in a rapid sequence such as a movie.

Moreover, recent physiological findings indicated that there are neurons selectively tuned for motion energy in the striate cortex. But these cells are not only the ones involved in motion perception, since humans can perceive motion involving spatio-temporal structures that lack motion energy in the direction of perceived motion. To detect this higher-order motion, there must be mechanisms involving more complex processing; some of these systems also appear to operate over longer times and distances than the basic motion energy mechanisms.