Adaptation to gradual as compared with sudden visuo-motor distortions

If visual feedback is discordant with movement direction, the visuo-motor mapping is disrupted, but can be updated with practice. In this experiment subjects practiced discrete arm movements under conditions of visual feedback rotation. One group was exposed to 10 degrees-step increments of visual feedback rotation up to a total of 90 degrees, a second group to a 90 degrees visual feedback rotation throughout the experiment. After the first group reached the 90 degrees visual feedback rotation, its subjects performed faster, with less spatial error, and showed larger aftereffects than the subjects who practiced constantly under the 90 degrees visual feedback rotation condition. Results suggest that gradually increasing feedback distortion allows more complete adaptation than a large, sudden distortion onset.