Visual Processing of Object Velocity and Acceleration.
Final technical rept. 30 Sep 82-29 Sep 85,
SMITH-KETTLEWELL EYE RESEARCH FOUNDATION SAN FRANCISCO CA
Pagination or Media Count:
The spatial and temporal constraints of human velocity discrimination were determined for continuous and sampled apparent motion targets. In the fovea, sampled motion is an adequate substitute for continuous motion provided that the samples are separated by less than 50 msec in time and 20 arcmin in space. Optimum velocity discrimination requires a total target duration of 80-100 msec. Measurements with drifting sinusoidal targets showed that random variations in spatial and temporal frequency did not affect the precision of velocity discrimination, indicating that velocity discrimination depends on velocity, not temporal frequency. Random variations in contrast also do not affect velocity discrimination. At faster velocities, velocity discrimination in the periphery is as precise as foveal discrimination, but is considerably worse at slow velocities the slowest velocity producing optimal discrimination scales with the visual acuity of the eccentric retinal location.
- Anatomy and Physiology