An emotional deficit in individuals with psychopathy has been regarded as a potential factor in the disinhibition of selfish behaviors, which can be an impediment to a successful life in human society. However, recent studies in the field of economics have made clear that emotional function is associated with irrational decision-making. In the present study, to test whether psychopathy may have a positive aspect in a social setting, we examined the decision-making of college students with high and low tendencies for (...) psychopathy in the ultimatum game, which illustrates conflict between fairness and economic utility. We also investigated electrodermal responses to fair and unfair offers for each group. Compared to low psychopathic controls, individuals with a high tendency toward psychopathy more often choose economic utility by accepting unfair offers. Whereas controls more often exhibited an electrodermal response to unfair offers compared to fair offers, high psychopathic individuals did not show a similar difference between the types of offer. The results suggest that the affective deficit of psychopathy might be associated with insensitivity to unfairness and may contribute to a rational decision to accept unfair offers. Hence, psychopathy can be rational in some social situations. (shrink)