Sex Differences in the Effects of Psychosocial Stress on Cooperative and Prosocial Behavior: Evidence for ‘Flight or Fight’ in Males and ‘Tend and Befriend’ in Females

This study tested the hypothesis that human behavioral responses to psychosocial stress are sexually dimorphic and conform to the ‘flight-or-fight’ response for males and ‘tend-and-befriend’ for females. One hundred and twenty young adults (60 male, 60 female), mostly college students, served as study participants. Participants were randomly assigned to either a stress condition (Trier Social Stress Test, a standardized laboratory procedure used to induce psychosocial stress) or a control condition. Stress induction was confirmed with self-report questionnaires about perceived stress and anxiety. Participants then underwent three social decision making tasks to assess their competitive and cooperative tendencies: an Ultimatum Game, a Prisoner’s Dilemma, and a Prosocial Risk Taking task. We found evidence for interactive effects of stress and sex in all three tests, and all interactions were in the same direction. Relative to controls, stressed males made lower monetary offers to their partners and tended to be less willing to behave prosocially in a hypothetical risky situation, whereas stressed females offered higher monetary amounts in the Ultimatum Game and behaved more cooperatively in the Prisoner’s Dilemma. These results suggest that stress renders males more selfish and competitive, while stressed females become more other-oriented, more generous, and more cooperative. These effects are consistent with the ‘flight or fight’ pattern for males and the ‘tend and befriend’ pattern for females, respectively. The role of risk taking and empathy as possible psychological mediators of the effects of acute psychosocial stress on social decision making in men and women needs to be further investigated, along with sex differences in physiological responsiveness to stress.