Abstract
Recently is has been suggested that color is processed faster than motion (Zeki & Bartels, Proc. R. Soc. Lond. B 265, 1583 – 1585). To test this we have made use of color-contingent motion adaptation. The stimulus was a radial luminance-modulated grating. During adaptation the grating oscillated between being green-black and red-black and between rotating clockwise and anti-clockwise. The period of oscillations was 1 sec. The phasic relationship between changes in color and direction of motion was manipulated. At a phasic relationship of 0, clockwise rotation was always green-black and anticlockwise was always red-black. At a phasic relationship of 180 this situation was reversed. A range of phasic relationships from 0 to 324 in steps of 36 (which corresponds to steps of 100ms) was used. At a phasic relationship of 108 degrees, clockwise rotation was physically paired with the red-black color state for 300ms, and with the green-black color state for only 200ms. Yet the contingent aftereffects observed were consistent with clockwise rotation being perceptually correlated more highly with the green-black color state. The reverse situation was observed at a phasic relationship of 288. This indicates that changes in color are processed more than 50ms faster than changes in direction. This is consistent with the hypothesis that the evident processing asynchrony results in an asynchrony of visual consciousness.