Perceived speed of colored stimuli

The influence of contrast and color on perceived motion was measured using a speed-matching task. Observers adjusted the speed of an L cone contrast p attern to match that of a variety of colored test patterns. The dependence of speed on test contrast was the same for ail test colors measured, differ ing only by a sensitivity factor. This result suggests that the reduced app arent speed of low contrast targets and certain colored targets is caused b y a common cortical mechanism. The cone contrast levels that equate perceiv ed speed differ substantially from those that equate visibility. This resul t suggests that the neural mechanisms governing speed perception and visibi lity differ. Perceived speed differences caused by variations in color can be explained by color responses that are characteristic of motion-selective cortex.