Shared responsibility decreases the sense of agency in the human brain

Abstract

Distributing 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.

Stage 2 Registered Report: How responsibility attributions to self and others relate to outcome ownership in group decisions

“…This is quite surprising as participants rated all three players at each trial and suggests that responsibility attributions do not rely on a purely additive process, making them prone to changes based on outcome valence and ownership. A limitation of our study, however, is that we did not ask for responsibility ratings before the outcome to compare shifts in responsibility from the moment of the decision to the outcome 24 . This could have allowed us to directly compare pre and post outcome responsibility based on ownership, and to assess whether there is a specific increase for positive outcomes and/or decrease for negative outcomes from a baseline prospective responsibility level.…”