Oxytocin increases generosity in humans

Abstract

Human beings routinely help strangers at costs to themselves. Sometimes the help offered is generous-offering more than the other expects. The proximate mechanisms supporting generosity are not well-understood, but several lines of research suggest a role for empathy. In this study, participants were infused with 40 IU oxytocin (OT) or placebo and engaged in a blinded, one-shot decision on how to split a sum of money with a stranger that could be rejected. Those on OT were 80% more generous than those given a placebo. OT had no effect on a unilateral monetary transfer task dissociating generosity from altruism. OT and altruism together predicted almost half the interpersonal variation in generosity. Notably, OT had twofold larger impact on generosity compared to altruism. This indicates that generosity is associated with both altruism as well as an emotional identification with another person.

Figure 1. Oxytocin and generosity.

Mean DM1 generosity (DM1 UG offer minus average minimum acceptable offer) for those receiving OT or placebo. Generosity is 80% larger in the OT group (p = 0.005, N = 68). The increased generosity is not due to altruism as OT infusion in a task designed to isolated altruism showed no impact relative to placebo (p = 0.51, N = 68).