Directional adaptation effects with contrast modulated stimuli

In this study we investigated the directional selectivity of the mechanisms used to encode the motion of contrast modulated stimuli. Unlike luminance-domain stimuli, contrast-domain stimuli fail to generate convincing motion aftereffects. On the other hand, contrast-domain stimuli produce other direction specific adaptation effects that are as large as those produced by luminance-domain stimuli. The results of this study indicate that the dissociation between these two measures of directional selectivity might result from differences in the temporal nature of the test probe they employ. Specifically, it is suggested that the mechanisms which encode the motion of contrast modulated stimuli reveal their directional selectivity only when tested with a dynamic stimulus.