Dissociable neural connectivity patterns for decision and outcome phases in the stag hunt game: evidence from electroencephalography weighted phase lag index analysis.

This study aimed to investigate phase-based functional connectivity during decision-making and outcome evaluation in the stag hunt game using electroencephalography (EEG). Thirty-five healthy participants completed a repeated stag hunt task while EEG was recorded. Functional connectivity was assessed using the weighted phase lag index. Paired-sample t tests were conducted to compare connectivity strength between (a) cooperative vs. defective choices during the decision phase (200-300 ms, theta band) and (b) gain vs. loss feedback during the outcome phase (200-500 ms, delta band). During the decision phase, theta-band connectivity was significantly higher for defect choices in frontocentral and parietal electrode pairs (e.g. FC2-C4, CP4-FC2). During the outcome phase, gain feedback elicited stronger delta-band connectivity across frontoparietal and fronto-occipital networks (e.g. AF8-O1/O2, CP2-Cz, and PO7-AF8). These findings reveal distinct oscillatory connectivity patterns associated with social decision-making and reward evaluation. Defection involves enhanced frontoparietal theta synchronization linked to cognitive control, whereas gain feedback engages broader delta networks related to reward processing. This study provides novel insights into the neural dynamics of cooperation and defection in social contexts.