Flexible Cognitive Strategies during Motor Learning

Abstract

Visuomotor rotation tasks have proven to be a powerful tool to study adaptation of the motor system. While adaptation in such tasks is seemingly automatic and incremental, participants may gain knowledge of the perturbation and invoke a compensatory strategy. When provided with an explicit strategy to counteract a rotation, participants are initially very accurate, even without on-line feedback. Surprisingly, with further testing, the angle of their reaching movements drifts in the direction of the strategy, producing an increase in endpoint errors. This drift is attributed to the gradual adaptation of an internal model that operates independently from the strategy, even at the cost of task accuracy. Here we identify constraints that influence this process, allowing us to explore models of the interaction between strategic and implicit changes during visuomotor adaptation. When the adaptation phase was extended, participants eventually modified their strategy to offset the rise in endpoint errors. Moreover, when we removed visual markers that provided external landmarks to support a strategy, the degree of drift was sharply attenuated. These effects are accounted for by a setpoint state-space model in which a strategy is flexibly adjusted to offset performance errors arising from the implicit adaptation of an internal model. More generally, these results suggest that strategic processes may operate in many studies of visuomotor adaptation, with participants arriving at a synergy between a strategic plan and the effects of sensorimotor adaptation.

Knowledge of Performance is Insufficient for Implicit Visuomotor Rotation Adaptation

“…Moreover, subjects' answers at the end of the experiments imply that the reason for this error reduction is not necessarily an internal implicit process of motor learning but rather a combination of explicit strategies. This finding is consistent with the work of Taylor and Ivry (2011) who demonstrated that a prolonged exposure to a rotation without any feedback influences which strategy subjects use.…”

“…Interestingly, even though subjects in other studies could not use strategies which were explicitly provided by the experimenters (Mazzoni and Krakauer, 2006;Taylor and Ivry 2011), our subjects succeeded using explicit strategy for compensating the rotation. This finding may result from the fact that our subjects formed their own strategies without any verbal instructions.…”

Delayed feedback during sensorimotor learning selectively disrupts adaptation but not strategy use

“…This block provides a stronger assessment of the size of the aftereffect since errorbased unlearning is precluded by the absence of visual feedback (Kitago et al 2013). During this block, the participants were asked to aim directly to the target, and to refrain from using an aiming strategy they may have developed during the Rotation block (Taylor et al 2014;Taylor and Ivry 2011).…”

“…The preceding discussion suggests that outcome-based feedback may not influence motor adaptation directly but, rather, influences other learning processes that operate during sensorimotor adaptation tasks such as operant conditioning (Shmuelof et al 2012) and explicit strategic aiming McDougle et al 2015;Taylor et al 2014;Taylor and Ivry 2011). Moreover, these other processes may have temporal constraints different from that associated with adaptation, allowing learning to occur under conditions with significant feedback delays.…”

Formation of a long-term memory for visuomotor adaptation following only a few trials of practice

“…Adaptation is known to be supported by explicit processes, especially early in learning, which act in parallel with implicit, predictionerror-driven components (Redding and Wallace 2003;Mazzoni and Krakauer 2006;Keisler and Shadmehr 2010;Benson et al 2011;Taylor and Ivry 2011;Taylor et al 2014). This explicit process may involve, for instance, choosing to aim in a direction other than towards the target when adapting to a rotation (Taylor et al 2014).…”