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.