Selfish and prosocial individuals both distort their actions’ impact, but selfish distortions can be more contagious

People often act without fully knowing how their actions impact others. Do people take advantage of this ambiguity to make themselves look good? And how do these distortions influence others? In a series of experiments (N=8,769), selfish individuals inflated how much their choice benefitted others and downplayed the social benefits of the alternative. Generous individuals, by contrast, portrayed their choice as having greater social benefit and inflated their relative sacrifice. We observed distortions even before people made a choice and when choices were forced. Although people differed in whether and how they distorted, some distortions were particularly conducive to social transmission. Specifically, only distortions favouring selfishness were contagious: others adopted them and became more selfish. These findings provide a psychological foundation for why polarized positions emerge around issues like climate change mitigation, foreign aid, and social welfare. When social consequences are open to interpretation, people may predictably form divergent interpretations.