Sensorimotor adaptation in color: transfer properties with respect to direction and amplitude of the eye sac- cade

Previous work (Bompas & O’Regan, 2006a, 2006b) revealed that color perception is subject to sensorimotor adaptation, i.e. to a perceptual adaptation whose effects depend on actions. In these experiments we had shown that the introduction of new sensorimotor contingencies between eye movements and color changes resulted in a consistent perceptual bias affecting color comparison judgements made across an eye saccade. In the present article, we study the dependency of this effect on two properties of the eye saccade: amplitude and direction. As saccade direction in the test stage increasingly deviates from the horizontal rightwards saccade performed during adaptation, the perceptual shift decreases. The effect is still present for pi/8 but disappears for larger differences (pi/4 to pi/2). On the other hand, the perceptual bias proves very robust to changes in the amplitude of the saccade performed during the test stage: the effect is still measurable for saccades four times smaller or twice larger than during adaptation, and no clear dependency of the amplitude of the effect on the amplitude of the eye saccade was obtained. This difference in transfer properties could indicate that the effect involves the initiation stage of the eye saccade, which would confirm that the perceptual effect results from the up-dating of a prediction function linking eye saccades and color changes.