Mechanisms for sensorimotor adaptation to rotated visual input.

Using the multiple-exposure approach, we investigated sensorimotor adaptation by exposing human subjects to different angles of visual rotation in a tracking task. Generally, the tracking error was high at the onset of the visual rotation and gradually declined towards the baseline level during the exposure period. In experiment A, we confirmed that the initial tracking error increases more than proportionally with the angle of rotation. In experiment C, we were unable to confirm intermanual transfer, and attribute this discrepancy with previous literature to details of the experimental tasks. In our main experiment, B, we found that pre-exposure to 45 degrees or 60 degrees of visual rotation facilitated the subsequent adaptation to a 90 degrees rotation, with the facilitatory effect being more pronounced following the 60 degrees rotation. We interpret this finding as evidence that adaptation is achieved by a gradual process, which progresses from small angles of output transformation through intermediate values up to the prescribed angle of rotation.