Lukas J. Volz, B. Locke Welborn, Matthias S. Gobel, Michael S. Gazzaniga, and Scott T. Grafton
PNAS 2017 ; published ahead of print July 10, 2017
How we make decisions that have direct consequences for ourselves and others forms the moral foundation of our society. Whereas economic theory contends that humans aim at maximizing their own gains, recent seminal psychological work suggests that our behavior is instead hyperaltruistic: We are more willing to sacrifice gains to spare others from harm than to spare ourselves from harm. To investigate how such egoistic and hyperaltruistic tendencies influence moral decision making, we investigated trade-off decisions combining monetary rewards and painful electric shocks, administered to the participants themselves or an anonymous other. Whereas we replicated the notion of hyperaltruism (i.e., the willingness to forego reward to spare others from harm), we observed strongly egoistic tendencies in participants’ unwillingness to harm themselves for others’ benefit. The moral principle guiding intersubject trade-off decision making observed in our study is best described as egoistically biased altruism, with important implications for our understanding of economic and social interactions in our society.
Principles guiding decisions that affect both ourselves and others are of prominent importance for human societies. Previous accounts in economics and psychological science have often described decision making as either categorically egoistic or altruistic. Instead, the present work shows that genuine altruism is embedded in context-specific egoistic bias. Participants were willing to both forgo monetary reward to spare the other from painful electric shocks and also to suffer painful electric shocks to secure monetary reward for the other. However, across all trials and conditions, participants accrued more reward and less harm for the self than for the other person. These results characterize human decision makers as egoistically biased altruists, with important implications for psychology, economics, and public policy.
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