Implicit adaptation processes appear unable to account for learning in sensorimotor adaptation tasks

Learning 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 on results from single bouts of training, thus, it is possible that implicit adaptation processes supersede explicit re-aiming strategies 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. Implicit adaptation 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. Implicit adaptation was inappropriate for mirror reversal and became suppressed during training. We suggest that the implicit adaptation process studied in sensorimotor adaptation paradigms cannot support long-term motor skill learning.