Are humans ever truly altruistic? Or are all actions, however noble, ultimately motivated by self-interest? Psychologists and philosophers have long grappled with this question, but few have considered laypeople’s beliefs about the nature of prosocial motives. Here we examine these beliefs and their social correlates across two experiments (N = 445). We find that people tend to believe humans can be, and frequently are, altruistically motivated—echoing prior work. Moreover, people who more strongly believe in altruistic motives act more prosocially themselves—for instance, sacrificing greater amounts of money and time to help others—a relationship that holds even when controlling for trait empathy. People who believe in altruistic motives also judge other prosocial agents to be more genuinely kind, especially when agents’ motives are ambiguous. Lastly, people independently show a self-serving bias—believing their own motives for prosociality are more often altruistic than others’. Overall, this work suggests that believing in altruistic motives predicts the extent to which people both see altruism and act prosocially, possibly reflecting the self-fulfilling nature of such lay theories.

人类真的是无私的吗？还是所有的行为，无论多么崇高，最终都是出于自身利益的动机？心理学家和哲学家长期以来一直在努力解决这个问题，但很少有人考虑外行人对亲社会动机本质的看法。在这里，我们通过两个实验（N = 445）检查了这些信念及其社会相关性。我们发现，人们倾向于相信人类可以并且经常是具有利他动机的——这与之前的工作相呼应。此外，更坚信利他动机的人自己的行为更亲社会——例如，牺牲更多的金钱和时间来帮助他人——即使在控制特质移情的情况下，这种关系仍然存在。相信利他动机的人也会判断其他亲社会的代理人更真诚善良，尤其是当代理人的动机不明确时。最后，人们独立地表现出自私的偏见——相信自己的亲社会动机往往比其他人更利他。总体而言，这项工作表明，相信利他动机可以预测人们在多大程度上看到利他主义并采取亲社会行为，这可能反映了此类非专业理论的自我实现性质。