Interactive priming enhanced by negative damping aids learning of an object manipulation task

We investigated how free interaction with an object influences the formation of motor planning. Subjects controlled a force-feedback planar manipulandum that presented simulated anisotropic inertial forces. As a performance evaluation, subjects made circular movements about a prescribed track. In order to investigate potential enhancement of motor planning, we introduced negative damping during an ldquointeractive primingrdquo phase prior to task performance. As a control, we presented a second subject group with normal interactive priming. Our results showed significantly greater reduction in maximum curvature error for the subject group that received enhanced priming (two-tailed T-test, p=1.86e-6) compared to the control group. Group-I demonstrated a 34.8% reduction in error while Group-II achieved 5.78% reduction. We also observed that the presentation of enhanced priming evidently caused a greater sensitivity to catch trials compared to the control. Group-I demonstrated a larger increase (92.0%) in maximum curvature error in catch- trials (with respect to baseline), compared to Group-II (50.8%) during early training (two-tailed T-test, p=1.9e-3). These results suggest that some forms of augmentation to task dynamics - leading to the exploration of a broader state space -can help the accelerate the learning of control strategies suitable for an unassisted environment. The finding is also consistent with the hypothesis that subjects can decompose the environment impedance into acceleration and velocity dependent elements.