The role of reward-based motivation in motor learning and performance

Human behaviour is crucially driven by motivation, which allows the pursuit of goals by supporting an efficient inspection of the surrounding environment and by enabling execution of the more convenient motor actions to interact with it. Motivation can be successfully manipulated by simply delivering rewarding (or punishing) consequences in return to behavioural performance. The aim of this research was to study how the learning of a visuo-motor behavioural pattern may be influenced by different motivational contexts. To this purpose, we developed a computerized training protocol able to induce learning of specific motor patterns and examined performance in this new task in four different groups with different degrees of motivational engagement. The four protocols adopted in the different groups were: 1) without any kind of reward or feedback information (Experiment 1); 2) with an error feedback, signaling trials with poor performance (Experiment 2); 3) with a monetary incentive signaling the availability of a variable prize in turn for accurate performance in the forthcoming trial (Experiment 3); 4) with a monetary feedback, delivering a variable reward immediately after trials with an accurate performance (Experiment 4). The new visuo-motor task to be learned, required to move the index finger over a potentiometer in order to keep a cursor within the boundaries of a curvilinear path sliding across the computer screen. The protocol was characterized by: 9 sessions of training in consecutive days, 3 retention sessions and 2 test sessions at different time lags from the last training day. On each session participants had to complete 160 trials. In Experiments 3 and 4 reward signals were delivered during both training and retention sessions. No reward was delivered during the test sessions. A first, comprehensive data analysis was carried out through a repeated measures analysis of variance (ANOVA) with Experiment (1 to 4) as the between-subjects factor and Session as the within-subjects factor. Overall, Time In performance (the time spent by the cursor inside the moving path) increased significantly across sessions, reaching a plateau only after 7 days from the beginning of training. By comparing the overall level of performance across experiments it was clear that the highest scores were obtained by participants in Experiment 4 and the lowest scores were obtained in Experiment 1. Our data showed that, under high motivational engagement, motor learning developed earlier, and its effects were longer lasting compared to the condition in which no feedback was present. In line with the translational nature of this project, the next step will be to devise new protocols of visuo-motor training grounded on these findings, pivoting on the delivery of rewarding feedbacks 1) to promote faster and more efficient recovery of visuo-motor functions in patients with cerebral stroke 2) to increase motor energy and, in this way, facilitate the application and improve the efficacy of most rehabilitation programs with patients with Parkinson’s disease.