NEURAL ADAPTATION OF IMAGINARY VISUAL-MOTION

Observers made time-to-contact judgments about an imagined moving obje ct that passed through an area of the visual field previously adapted to a single direction of real motion. The direction of imagined motion varied relative to the direction of adapting motion. When imagined mo tion was in the same direction as that experienced during adaptation, imagined speed was slowed; when imagined motion was in the opposite di rection, its speed was increased; when adaptation and imagined motions were orthogonal, imagined speed was unaffected. The particular influe nce that prior adaptation has on imagined speed suggests that imagined motion and real vision may engage common neural mechanisms without be ing functionally equivalent. Negative aftereffects observed in imagine d motion imply that the imagination represents movement as an inferenc e from position changes of static images. (C) 1995 Academic Press, Inc .