Jason Mitchell (Harvard University)
Abstract. Standard models within behavioral economics and evolutionary biology have assumed that individuals seek to maximize their personal well-being, such that when choosing between improving outcomes for oneself or for others, people will consistently act selfishly. However, this assumption is met with the uncomfortable truth that humans commonly engage in patently unselfish acts, such as helping strangers, cooperating with others, and distributing resources fairly, even from very young ages. Many theorists have attempted to preserve the view that humans primarily act for selfish motives by positing that what passes as prosocial behavior results from selfish attempts to protect one’s reputation or avoid retribution, such that even purely self-interested individuals might act prosocially simply as a way to avoid negative social consequences. Our recent work has contributed to an alternate account of human prosociality that suggests that, contrary to these claims, people act altruistically because doing so is experienced as a source of intrinsic reward in its own right. This work has capitalized on a rich and growing body of neuroscience research that has reliably demonstrated that activity in mesolimbic dopaminergic targets—including the nucleus accumbens (NAcc) and orbitofrontal cortex (OFC)—strongly correlates with the subjective value of reward in both humans and other animals, including primary and secondary rewards. In our recent work, we have consistently observed that these brain regions can be engaged by yet another type of event: opportunities to act generously to others, even at a material cost to the self. Such observations suggest that prosocial behavior represents a powerful source of motivation for many people.