View article

An aversion to harming others is a core component of human morality and is disturbed in antisocial behavior [1–4]. Deficient harm aversion may underlie instrumental and reactive aggression, which both feature in psychopathy [5]. Past work has highlighted monoaminergic influences on aggression [6–11], but a mechanistic account of how monoamines regulate antisocial motives remains elusive. We previously observed that most people show a greater aversion to inflicting pain on others than themselves [12]. Here, we investigated whether this hyperaltruistic disposition is susceptible to monoaminergic control. We observed dissociable effects of the serotonin reuptake inhibitor citalopram and the dopamine precursor levodopa on decisions to inflict pain on oneself and others for financial gain. Computational models of choice behavior showed that citalopram increased harm aversion for both self and others, while …