OPTIMIZING THE USE OF VISION IN MANUAL AIMING - THE ROLE OF PRACTICE

The purpose of this study was to determine how subjects learn to adjus t the characteristics of their manual aiming movements in order to mak e optimal use of the visual information and reduce movement error. Sub jects practised aiming (120 trials) with visual information available for either 400 msec or 600 msec. Following acquisition, they were tran sferred to conditions in which visual information was available for ei ther more or less time. Over acquisition, subjects appeared to reduce target-aiming error by moving to the target area more quickly in order to make greater use of vision when in the vicinity of the target. Wit h practice, there was also a reduction in the number of modifications in the movement. After transfer, both performance and kinematic data i ndicated that the time for which visual information was available was a more important predictor of aiming error than the similarity between training and transfer conditions. These findings are not consistent w ith a strong ''specificity of learning'' position. They also suggest t hat, if some sort of general representation or motor programme develop s with practice, that representation includes rules or procedures for the utilization of visual feedback to allow for the on-line adjustment of the goal-directed movement.