Neural responses underlying extraordinary altruists’ generosity for socially distant others

Abstract

People typically sacrifice fewer resources for socially distant others than close others, a bias termed social discounting. But people who engage in extraordinary real-world altruism, such as altruistic kidney donors, show dramatically reduced social discounting. Why they do so is unclear. Some prior research suggests generosity toward strangers requires effortfully overcoming selfishness bias. Alternately, generosity for strangers could reflect genuinely valuing strangers’ welfare more. We tested both hypotheses in this pre-registered study. Extraordinary altruists and demographically matched controls completed a social discounting task during fMRI scanning. In addition, we tested whether an eight-week Metta meditation training would reduce social discounting in typical adults. During fMRI, participants (N=77) chose selfish or generous options benefiting others at varying social distances. Behavioral results replicated altruists’ reduced social discounting relative to controls. Neither behavioral nor imaging analyses yielded support for the possibility that extraordinary altruism reflects effortfully overcoming a selfishness bias. Instead, we identified group differences in a constellation of social brain regions, including amygdala and rostral anterior cingulate, in which activation reflects the subjective valuation of distant others’ welfare. We found no effects of Metta training on behavioral or neural responses. Our results indicate altruists are more generous to strangers because regions involved in social decision-making encode the subjective value of distant others’ welfare differently than controls. As a result, altruists genuinely value distant others’ welfare more. Interventions aimed at promoting generosity for distant others may succeed to the degree they can alter neural processes supporting the subjective valuation of distant others’ welfare.

Unselfish traits and social decision-making patterns characterize six populations of real-world extraordinary altruists

“…In that subjective value is typically defined as the internal value a stimulus has to motivate choices and behavior 60 , these findings may help to understand motivations underlying extraordinary altruism. Although the neural mechanisms that determine the subjective value of outcomes for the self are well delineated [61][62][63][64] , relatively less work has focused on processes underpinning the subjective valuation of outcomes for others 44,[65][66][67] . Previous work suggests a critical role for variation in the structure and function of brain regions such as the amygdala in extraordinary altruism 10 .…”

Does impartial altruism incur costs in close relationships?

“…They engage in reduced social discounting, such that their generosity towards others decreases minimally as social distance increases [8][9][10] . Relative to controls, they show increased self-other overlap in neural responses to strangers' distress 11 ; subjectively value distant other's well-being 12 ; and preferentially endorse impartial bene cence, or the ideal of helping others regardless of social closeness, on the Oxford Utilitarianism Scale 13 . By contrast, altruists score no higher than controls in measures such as self-reported empathy, conscientiousness, or risk sensitivity 10 .…”

Does impartial altruism incur costs in close relationships?

“…They engage in reduced social discounting, such that their generosity towards others decreases minimally as social distance increases [8][9][10] . Relative to controls, they show increased self-other overlap in neural responses to strangers' distress 11 ; subjectively value distant other's well-being 12 ; and preferentially endorse impartial beneficence, or the ideal of helping others regardless of social closeness, on the Oxford Utilitarianism Scale 13 . By contrast, altruists score no higher than controls in measures such as self-reported empathy, conscientiousness, or risk sensitivity 10 .…”