Reward boosts reinforcement-based motor learning

Abstract

Besides relying heavily on sensory and reinforcement feedback, motor skill learning may also depend on the level of motivation experienced during training. Yet, how motivation by reward modulates motor learning remains unclear. In 90 healthy subjects, we investigated the net effect of motivation by reward on motor learning while controlling for the sensory and reinforcement feedback received by the participants. Reward improved motor skill learning beyond performance-based reinforcement feedback. Importantly, the beneficial effect of reward involved a specific potentiation of reinforcement-related adjustments in motor commands, which concerned primarily the most relevant motor component for task success and persisted on the following day in the absence of reward. We propose that the long-lasting effects of motivation on motor learning may entail a form of associative learning resulting from the repetitive pairing of the reinforcement feedback and reward during training, a mechanism that may be exploited in future rehabilitation protocols.

The dissociable effects of reward on sequential motor behaviour

“…In contrast, accurate performance feedback will lead to learning-related improvements across training. Importantly, in line with recent findings, we hypothesised that combining explicit reward with accurate performance feedback will maximise performance gains 15 .…”

“…transient improvement within a single trial) 1,3–5,11–14 , research employing force and button-press tasks showed reward-related improvements in learning and/or retention (i.e. improvements across trials) 8–10,15–17 . Therefore, a mechanistic account for how reward enhances motor performance is lacking, which restricts the potential of a targeted use of reward in clinical settings.…”

“…An interesting possibility is that these distinct reward-based improvements are driven by dissociable reward types. Reward is most commonly provided through either explicit reward (i.e., money), performance feedback (i.e., points) or a combination of both 4,8–10,15 . Performance feedback represents a reinforcement-based teaching signal (i.e., reward-prediction error) 18,19 which provides information on how well a motor task has been completed (knowledge of performance) and has been shown to enhance other forms of motor learning 11,20–24 .…”

“…In contrast, explicit reward such as a monetary incentive increases the motivation to perform optimally without necessarily providing a performance-based learning signal 25 . Recent research decoupled explicit reward from performance feedback and found that while performance feedback alone was not sufficient to induce skill leaning in a pinch force reproduction task, combining it with explicit reward was 15 . However, the effect of explicit reward alone on motor behaviour was not accounted for 15 .…”

“…Recent research decoupled explicit reward from performance feedback and found that while performance feedback alone was not sufficient to induce skill leaning in a pinch force reproduction task, combining it with explicit reward was 15 . However, the effect of explicit reward alone on motor behaviour was not accounted for 15 . Therefore, to dissociate the effects of both on motor behaviour it is crucial to systematically assess them in isolation and in combination.…”