FOURSITES

INFLUENCE OF MOTION SIGNALS ON THE PERCEPTION OF SPATIAL PATTERN

The Motion After Effect (MAE) has been taken as psychophysical evidence for a functional dissociation since it is widely believed that the experience of motion after adaptation is not accompanied by a concommitant shift in spatial position. However, we measured the perceived orientation of a static windmill pattern after adaptation to motion and found a gradual shift in position in the same direction as the illusory rotation, though at a speed much slower than the perceived rotation speed. The orientation shift demonstrates that an internally generates motion signal can alter the appearance of a spatial pattern. This effect can persist longer than the motion aftereffect, and it disappeared when the motion aftereffect was nulled by physical motion. The persistence of the orientation shift leads us to suggest that the visual system represents spatial information within a neural buffer which is dynamically updated by systems integrating motion signals over time.