Adaptation of hand movements to double-step targets and to distorted visual feedback: evidence for shared mechanisms

Visuomotor adaptation of hand movements has been studied with two paradigms: double-step targets and distorted visual feedback. Here we investigate whether both procedures are based on a common adaptive mechanism. Subjects adapted either to double-step targets or to distorted feedback, each requiring a change of response angle by -15°. The magnitude of adaptation was larger with rotated feedback but magnitude of aftereffects was comparable, suggesting that the difference was due to strategic effects rather than visuomotor recalibration. Most importantly, subjects who adapted to double-step targets and were then exposed to rotated feedback performed as well as subjects who had fully adapted to rotated feedback, i.e., there was nearly 100% transfer from double-steps to rotations; likewise, the transfer from rotations to double-steps was almost 100%. From this we conclude that both types of adaptation share a common mechanism for recalibration.