It's subjective! Effects of perceptions of success and objective outcomes on feedback-related brain activity in a motor learning paradigm

Feedback processing affects motor learning and performance. Importantly, the same objective outcome can lead to feedback that is subjectively perceived as indicating success or failure depending on task instructions. To understand how practice conditions affect the rewarding value of feedback, we recorded participants’ electroencephalography while practicing a shuffleboard task under different criteria of success. We used mixed-effects models to investigate, on a trial-by-trial basis, how subjective success and objective error interact with each other to affect the feedback-related potential reward positivity (RewP), an index of reward prediction error. Results indicated that trials that met participants’ arbitrarily established criterion of success elicited larger RewP amplitudes than trials subjectively perceived as unsuccessful. Moreover, although smaller objective errors also resulted in larger RewP amplitudes compared to larger objective errors, we demonstrated that subjective success explained more RewP variance than objective error. We did not find sufficient evidence that criteria of success moderate the relationship between objective error and RewP, suggesting that error magnitude is interpreted in parallel and in addition to success, rather than one overriding the other. Overall, our results indicate that giving subjective meaning to learners’ performance outcomes can be an effective and simple way for instructors to manipulate the brain's reward systems during practice, especially because the subjective interpretation of the outcome can have more influence on RewP than the objective level of accuracy. Finally, we also add evidence to the literature that RewP is also responsive to graded objective feedback and outcome expectancies in a learnable motor task.