Effects of retinal eccentricity on displacement thresholds for unidirectional and oscillatory stimuli.

Motion sensitivity was determined for line stimuli undergoing unidirectional and oscillatory displacements at various retinal eccentricities. Oscillatory motions of short duration were found to produce consistently greater motion thresholds than unidirectional stimuli at each eccentricity tested. Increasing retinal eccentricity elevated motion thresholds similarly for both forms of stimulus motion. The observed differences between unidirectional and oscillatory stimuli are attributed to differences in the temporal summation of the two forms of stimuli at short duration. These findings also suggest that differences in motion sensitivity between central and peripheral vision are quantitative rather than qualitative.