Implicit visuomotor adaptation remains limited after several days of training
AbstractLearning in sensorimotor adaptation tasks has been historically viewed as solely an implicit learning phenomenon. However, recent findings suggest that implicit adaptation is heavily constrained, calling into question its utility in motor learning, and the theoretical framework of sensorimotor adaptation paradigms. These inferences have been based mainly on results from single bouts of training. Thus, it is possible that implicit adaptation processes supersede explicit compensation strategies, such as explicitly re-aiming their intended movement direction, over repeated practice sessions. We tested this by dissociating the contributions of explicit re-aiming strategies and implicit adaptation over five consecutive days of training. Despite a substantially longer duration of training, implicit adaptation still plateaued at a value far short of complete learning. We sought to determine if these constraints on implicit adaptation extend to another sensorimotor task, mirror reversal. As has been observed in previous studies, implicit adaptation was inappropriate for mirror reversal and was gradually suppressed over training. These findings are consistent with a handful of recent studies suggesting that implicit adaptation processes, as studied in sensorimotor adaptation paradigms, may only make subtle recalibrations of an existing skill and cannot contribute to motor skill learning de novo.Significance StatementIn this set of studies, we find that implicit adaptation cannot fully account for learning in adaptation tasks, such as the visuomotor rotation and mirror reversal tasks, even following several days of training. In fact, implicit adaptation can be counterproductive to learning. These findings question the utility of implicit adaptation processes to motor skill learning more broadly.
