Better together? The neural response to moral dilemmas is moderated by the presence of a close other.

Abstract

We investigated the modulation of neural and behavioral responses to moral dilemmasby the physical presence of a close friend. We argue that the presence of a close othernot only changes the moral response but also the process of decision-making, some-thing that can only be discovered by combining insights from social and cognitivepsychology. Our participants rated the acceptability of sacrificing ingroup members tosave outgroup members and vice versa while being alone or in the presence of a closeother. We obtained behavioral and functional MRI data from a within-participantfunctional MRI study (N17, native Dutch women). The behavioral data replicatedclassical identity theory with regard to higher acceptability to sacrifice the outgroup (vs.the ingroup) but did not show any differences when deciding alone or in the presenceof the friend. The imaging results did not reveal main and interaction effects in ourhypothesized brain areas. Exploratory analysis however revealed an interaction effectin a region previously found to be related to guilt and shame (superior frontal gyrus),such that reactions to the sacrifice of the outgroup evoked increased activation whenbeing together with a close other