Color-motion asynchrony assessed along the chromatic axes and with luminance variation

Color-motion asynchrony was fist reported by Moutoussis and Zeki (Proceedings of the Royal Society B, 264, 393-399, 1997), who showed that a motion direction change needs to precede a color change by approximately 80-120 ms in order for humans to perceive change as synchronous when a visual stimulus changes its direction of motion and color rapidly and repetitively. This phenomenon was investigated with stimuli with a single change of color and a single change of motion. The stimulus was varied along the L/(L+M) axis, along the S/(L+M) axis, or in luminance at a constant chromaticity. The psychophysical task was either a correspondence task or a temporal judgment task. The results showed that all three of the variations in color or luminance produced similar color-motion asynchronies, but the correspondence task consistently showed greater asynchrony (80-110 ms) than did the temporal order judgment task (45-70 ms). The results indicated that color-motion asynchrony is processed at cortical areas after cone-specific chromatic signals and luminance signals are integrated.