Extensive practice improves adaptation to unpredictable perturbations in a sequential coincident timing task.

Extensive practice is associated with a higher level of learning than practice until performance stabilization. This is partially attributable to the changes in the variability of the structure that control the motor skill that occur during practice. However, because both conditions result in performance stabilization, the error in the task performance does not decrease further, and it is necessary to introduce higher demands (e.g., unpredictable perturbations) into the task for differences between the two conditions to arise. This study aimed to investigate whether extensive practice contributes to adaptation to unpredictable perturbations in a sequential motor skill task as compared to practice until performance stabilization. Thirty-four self-reported right handed young adults performed a sequential coincident timing task and were assigned to two groups during the first phase of experiment: the stabilization group (SG) or the extensive practice group (EG), which differs with respect to the quantity of practice. In the second phase, both groups performed under equal conditions and the subjects practiced the same task performed in the first phase, but unpredictable changes in the velocity of the visual stimulus were occasionally introduced. The results suggest that extensive practice improves adaptation to unpredictable perturbations better than practice until performance stabilization and indicates that the motor learning process continues after performance stabilization.