Motor Learning Mechanisms are not modified by Feedback Manipulations in a Real-World Task

Abstract

Error-based and reward-based mechanisms of motor learning co-occur in real-world scenarios but are traditionally isolated in laboratory tasks via feedback manipulations. This study examines the distinctiveness of these mechanisms by applying a lab-based feedback manipulation to a real-world task. Using Embodied Virtual Reality (EVR) of pool billiards - allowing for full proprioception via interaction with the physical pool table, cue stick, and balls - we introduced visual perturbations to a real-world task. 32 participants (12 F) underwent two sessions learning a visuomotor rotation, once with error and once with reward feedback. While naive participants corrected the entire rotation with error feedback, only partial correction was observed with reward feedback, highlighting the influence of the feedback regime on learning. However, the reward-dependent motor variability, lag-1 autocorrelation decay, and inter-trial variability decay - all indicators of reward-based and skill learning - were higher in the error feedback session, suggesting that the provided visual feedback did not exclusively engage specific learning mechanisms. Analysis of post-movement beta rebound (PMBR), a brain activity marker of learning mechanisms, revealed a decrease in PMBR with reward feedback but no consistent trend during error feedback sessions. These findings support the behavioural results, suggesting that while reward feedback was absent in error conditions, participants still engaged in reward-based learning. This study underscores the complexity of motor learning processes and highlights that visual feedback by itself can not elucidate the interplay between error-based and reward-based mechanisms in real-world contexts.