TEMPORAL COHERENCE THEORY FOR THE DETECTION AND MEASUREMENT OF VISUAL-MOTION

A recent challenge to the completeness of some influential models of l ocal-motion detection has come from experiments in which subjects had to detect a single dot moving along a trajectory amidst noise dots und ergoing Brownian motion. We propose and test a new theory of the detec tion and measurement of visual motion, which can account for these sig nal-in-Brownian-noise experiments. The theory postulates that the sign als from local-motion detectors are made coherent in space and time by a special purpose network, and that this coherence boosts signals of features moving along non-random trajectories over time. Two experimen ts were performed to estimate parameters and test the theory. These ex periments showed that detection is impaired with increasing eccentrici ty, an effect that varies inversely with step size. They also showed t hat detection improves over durations extending to at least 600 msec. An implementation of the theory accounts for these psychophysical dete ction measurements.