Interpersonal relationship modulates brain responses to outcome evaluation when gambling for/against others: an electrophysiological analysis.

When individuals play a gambling task and their actions have consequences for observers, how are the brain responses of the performers modulated by their interpersonal relationship with the observers? To address this issue, we examined the event-related potentials responses in performers while they played two gambling games: one during which they tried to earn money for the observers instead of themselves (i.e., Experiment 1) and another gambling game during which they attempted to earn money from the observers (i.e., Experiment 2). In Experiment 1, ERP results showed that when gambling for either the friends or the strangers, the feedback-related negativity (FRN) responses were more negative-going to the losses than to the gains. The FRN effect (loss minus gain) was significantly larger when gambling for the friends than for the strangers. The general P300 response was more positive-going when gambling for the friends than for the strangers. These results suggested that gambling for others enables individuals to assess the outcome from the interests of the other people, consequently, the FRN response may be driven by the evaluative process related to interests of the others. Because one׳s own economic interests were not involved, the performers׳ brain responses during both the early, semi-automatic stage (i.e., the FRN) and the later, controlled stage (i.e., the P300) of outcome evaluation were modulated by the interpersonal relationship between the performers and the observers. In Experiment 2, ERP results revealed that when gambling against others, the FRN response was more negative-going to the losses than to the gains, as well. However, neither the FRN effect nor the general FRN response was modulated by interpersonal relationship. The general P300 response was more positive-going when gambling against the stranger than against the friend. These results suggested that when gambling against others, the performers׳ FRN response may be driven by two evaluative processes: one is related to the interests of their own, and another is related to the interests of the other people; and the former one plays a dominant role. Because of highly self-involvement, only the performers׳ brain responses during the later controlled stage of outcome evaluation were modulated by interpersonal relationship. The present study extended previous research on brain responses to outcome evaluation when decision making actions have consequences for the other people by suggesting that the FRN response in the performer could also be driven by two evaluative processes. In addition, whether the FRN in the performer was modulated by interpersonal relationship depends on which evaluative process plays a dominant role. However, the P300 in the performer could always be modulated by interpersonal relationship. These findings provide evidence on outcome evaluation being composed of an early semi-automatic primitive process and a later controlled cognitive/affective appraisal process.