Reward and feedback processing in voluntary task-switching: joint evidence from pupillometry and EEG

Abstract: The brain’s cognitive control mechanisms monitor for changes in the environment and regulate behavior according to internally-represented goals. When environments change (e.g. a new reward to be won), but the goal does not, goal shielding is required, to hedge against distractors. Overall, the brain must adapt to changes in the environment and compute the appropriate mental or behavioral action (cognitive flexibility). Cognitive flexibility is frequently measured via voluntary task-switching paradigms, in which participants freely choose when to switch. In reward-based VTS paradigms, a shape cues the reward value participants can receive and a feedback phase informs the participant for the trial’s outcome. Remarkably, few VTS studies have probed the neurophysiological mechanism underlying feedback receipt of negative outcomes. In the present study, 51 participants completed a VTS paradigm, consisting of a cue phase where reward cues were shown, the cognitive flexibility task (i.e. letter-number judgment task), and a feedback phase that showed the monetary reward earned following each response: low reward trials (1 cent) and high reward trials (10 cents). We utilize simultaneous eye-tracking and EEG to provide comprehensive neurophysiological indices of cue and feedback processing in reward-based VTS. Eye Tracking results showed increased arousal to high reward cues as compared to low reward cues consistent with prior literature; pupil dilation also tracked feedback outcomes that were surprising, indicating non-specific salience-related arousal for highly rewarding and highly unrewarding outcomes. EEG results showed a cue-N2 component sensitive to reward cue magnitude, and a late CNV component sensitive to reward vs. no reward cues. We observed increased theta power for outcomes of zero monetary reward compared to low reward feedback, indicating differentiated processing for reduced reward; theta power and pupil dilation were not correlated. Taken together, results show differentiated neurophysiological activity for anticipation of high monetary reward and following negative monetary outcomes. Our work may offer future directions for the role of negative affect in the processing of negative outcomes, affecting cognitive flexibility.