Abstract
The lowest velocity at which motion can be detected, the lower threshold of motion (LTM), has been investigated as a function of eccentricity. Results show that temporal properties of the LTM change with eccentricity, suggesting a dichotomy in the temporal properties of the neural mechanisms subserving this aspect of central and peripheral vision. Suprathreshold drifting sinusoidal gratings were used with a method of constant stimuli (a two-alternative forced-choice procedure) to obtain the LTM for different stimulus durations at different eccentricities. Results for central vision support a displacement-based model of movement detection similar to that of Reichardt [in Sensory Communication, W. A. Rosenblith, ed. ( Wiley, New York, 1961), p. 303]. The LTM decreases as the stimulus duration increases, thus maintaining a constant minimum displacement. However, the results for the far periphery (35 deg of eccentricity) suggest a different mechanism, in which detection depends not on a constant displacement but on a constant velocity; as the stimulus duration increases, the LTM remains constant. These results for gratings can also be generalized to other stimuli, for example, random-dot patterns presented in apparent motion.
© 1987 Optical Society of America
Full Article | PDF ArticleMore Like This
M. J. Wright
J. Opt. Soc. Am. A 4(8) 1627-1633 (1987)
Guy A. Orban, Frank Van Calenbergh, Bart De Bruyn, and Hugo Maes
J. Opt. Soc. Am. A 2(11) 1836-1847 (1985)
W. A. van de Grind, J. J. Koenderink, and A. J. van Doorn
J. Opt. Soc. Am. A 4(8) 1643-1652 (1987)