Savings upon Re-Aiming in Visuomotor Adaptation.

Sensorimotor adaptation has traditionally been viewed as a purely error-based process. There is, however, growing appreciation for the idea that performance changes in these tasks can arise from the interplay of error-based adaptation with other learning processes. The challenge is to specify constraints on these different processes, elucidating their respective contributions to performance, as well as the manner in which they interact. We address this question by exploring constraints on savings, the phenomenon in which people show faster performance gains when the same learning task is repeated. In a series of five experiments, we demonstrate that error-based learning associated with sensorimotor adaptation does not contribute to savings. Instead, savings reflects improvements in action selection, rather than motor execution. SIGNIFICANCE STATEMENT: Savings is the phenomenon in which people show faster relearning of a previously forgotten memory. In the motor learning domain, this phenomenon has been a puzzle for learning models that operate exclusively on error-based learning processes. We demonstrate, in a series of experiments, that savings selectively reflects improvements in action selection: Participants are more adept in invoking an appropriate aiming strategy when presented with a previously experienced perturbation. Indeed, improvements in action selection appear to be the sole source of savings in visuomotor adaptation tasks. We observe no evidence of savings in implicit error-based adaptation.