Influence of motor learning on utilizing path redundancy

We examined the role of motor learning in influencing the utilization of path redundancy in an interception task. Participants used a pen on a digitizing tablet with the goal of moving to intercept a stationary target shown on a computer screen. Concurrent visual feedback of the cursor and knowledge of results were provided. The changes in spatial variability after extended practice and the correlations between spatial locations on the path were consistent with the view that path redundancy was utilized. However, paths also became less variable with practice, indicating that less of the solution space was utilized. There was also a sequential relation in the movement paths from trial to trial with a tendency to use more similar movement paths on successive trials. These results show that models that account for both redundancy and invariance may be better able to capture the changes in variability with learning. Further, the sequential dependence in the paths suggests that the exploration of redundant solutions is a systematic search process.