Sex differences on the response to others' gains and losses under cooperation and competition.

Although previous studies have shown that task performance is affected by others' presence and (the consequences of) others' actions, it is unclear how task performance varies in different social situations and the role that sex plays in it. In the present study, we investigated sex differences in the evaluation processing of another person's outcomes in both cooperative and competitive contexts. We recorded the event-related potentials (ERPs) of 72 normal adults who played a gambling task with a partner or against an opponent. The behavioral results indicate that males take longer to make decisions in competitive contexts, while females take longer to make decisions in cooperative contexts. According to the ERP findings, feedback-related negativity (FRN) was influenced by sex, with larger FRN following another person's loss among males in both cooperative and competitive contexts. The P300 was influenced by sex and context, such that males had greater P300 when another person made a gain under the cooperative context, while females had greater P300 when another person lost under the cooperative context. Our findings suggest that the processing of another person's outcome can be modulated by the sex during the early stage and by both the context and sex during the late stage.