Shared responsibility decreases the sense of agency in the human brain

Abstract

AbstractDistributing responsibility across several individuals in social decisions helps minimize a burden of responsibility for consequences of decisions. Here we investigated the neural expression of this effect using magnetoencephalography (MEG). Participants performed a reward-based learning decision-making task in contexts where their sense of responsibility over outcomes decreased with group size. An MEG outcome processing effect was reduced as a function of decreasing responsibility at 200ms post outcome onset and centred over parietal and precentral brain regions. During social decisions, prior to outcome revelation, a motor preparation signature at 500ms after stimulus onset was attenuated. A boost in responsibility for positive outcomes in social contexts was associated with increased activity in regions related to social and reward processing. Together, these results show that sharing responsibility with others reduces agency through an influence on pre-outcome motor preparation and post-outcome processing, affording an opportunity for flexibility in credit for positive outcomes.