The role of intervening patterns in the storage of the movement aftereffect.

Wohlgemuth, having measured the duration of the motion aftereffect (MAE), instructed subjects to close their eyes immediately after adaptation for a period of time longer than the MAE. Upon opening their eyes the subjects reported a residual effect, albeit somewhat shorter than the original effect. Thus the decay of the aftereffect appeared to have been retarded by the period of darkness. This effect is known as 'storage' and poses a problem for any model of the MAE based on the fatiguing of direction-selective units in the visual pathway. A reexamination is made of storage of the MAE, again concentrating on the intervening stimulation between movement adaptation and aftereffect test. The results suggest that the nature of the intervening pattern between adaptation and test conditions is remarkably unimportant. A total of 11 different storage patterns were examined after adaptation to high-contrast drifting horizontal sinewave gratings. For 10 of these patterns large and robust storage effects were found. The exception occurred when the spatial pattern of the storage stimulus was identical to the adaptation and test stimuli. It is proposed that storage cannot be understood in terms of a simple fatigue model of the MAE and that one component of the effect may share similarities with contingent aftereffects.