Contextual incongruency selectively modulates emotion and reward sensitivity.

Emotions and contexts play a fundamental role in shaping reward-based decision-making, yet the processes and mechanisms through which they influence decision strategies remain unclear. In this study, we employed two modified versions of the Iowa Gambling Task (IGT) to investigate how emotional cues (Experiment 1) and emotional feedback (Experiment 2) modulate decision-making by altering perceptions of reward outcomes across different contexts. Happy and fearful facial expressions were used as emotional stimuli, paired with positive and negative reward outcomes in congruent contexts, and reversed in incongruent contexts. We hypothesized that emotional stimuli would modulate attention and outcome evaluation, which also rely on contextual congruency, thereby guiding decision strategies distinctively. To test this, we analyzed trial-by-trial decision dynamics behaviorally and recorded neural activity using EEG. Behavioral results showed that both emotional valence (happy vs. fearful) and reward utility (gain vs. loss) significantly impacted decision strategies. Notably, emotional sensitivity was attenuated in incongruent contexts, while reward sensitivity remained unchanged. EEG data revealed that neural markers, including P2, FRN, and P300, encoded both emotional valence and reward utility, particularly in congruent contexts. In incongruent contexts, FRN and P300 amplitudes decreased in response to emotional stimuli but remained unchanged for reward sensitivity. In contrast, P2 amplitude was reduced for both emotional and reward sensitivity when emotional faces were presented as cues, but not when presented as feedback. These findings highlight the critical role of context in selectively shaping both behavioral and neural responses to emotion and reward.