Comparing local and remote motion aftereffects.

A new method, using phase-reversing sinusoidal gratings to cancel perceived motion, was developed to measure the motion aftereffect (MAE). This technique was used to show the existence of a remote MAE, i.e. an MAE in areas that were not directly stimulated during adaptation. In several experiments, this remote MAE was compared to the local MAE. The remote effect was generally weaker and of shorter duration. It showed no directional tuning within the investigated range, as compared to a tuning of +/- 60 deg of the local MAE. There was no adaptation effect to the component gratings of a plaid, indicating that the plaid was treated as a coherent pattern. The local MAE showed clear spatial frequency tuning, whereas the remote MAE varied little with spatial frequency difference, although there was a tendency towards frequencies lower than the adaptation frequency. The possibility is considered that both local and remote MAEs are generated in extrastriate areas.