The neurocomputational mechanisms underlying the impact of social comparison on effort investment

Previous research has shown that favorable monetary outcomes relative to others enhance neural responses; however, these paradigms often confound the subjective utility of social comparison with absolute reward magnitude. It remains unclear how performance-based social comparisons modulate an individual's self-efficacy and the subsequent effort mobilization. To address this gap, we conducted behavioral (N = 32) and electrophysiological (N = 34) experiments using a self-paced effortful task with downward/upward social comparison feedback. Computational modeling and multilevel mediation analyses revealed that downward (vs. upward) feedback dynamically updated self-efficacy, which fully mediated subsequent effort mobilization. Electrophysiological results showed stronger neural responses to downward versus upward feedback. Critically, downward comparison enhanced preparatory markers for the next round, including the contingent negative variation (CNV) and cue-beta power. Moreover, higher self-efficacy predicted more negative-going CNV potentials. These findings demonstrate that performance-based comparisons dynamically regulate self-efficacy, shaping both neural preparation and effort allocation in goal-directed behavior.