TRANSPARENT MOTION FROM FEATURE-BASED AND LUMINANCE-BASED PROCESSES

The apparent motion of a discretely displaced complex waveform with a periodic contrast modulation or ''beat'' of frequency f and sinusoidal components of frequencies 3f and 4f was examined at various interstimulus intervals (ISIs). At short ISIs perception of motion of both the beat and an aliased component of the waveform results in transparent motion. At longer ISIs motion is perceived only in the direction of the features of the waveform. The transparent motion observed at short ISIs indicates that, under certain conditions, ''short-range'' motion sensors do not constrain ''long-range'' feature processing and both may be active simultaneously.