关键词: 信任博弈, 决策过程, 结果评价, P2, FRN, P300

Abstract:

To trust or not to trust is a social dilemma which impacts our way of life. As an important social signaling mechanism, trust is critical to the development of long-term social relationships, which could reduce transaction costs, facilitate cooperative behavior, and promote the prosperity of human society. Previous fMRI research based on the Trust Game has revealed some brain regions recruited for the decision to trust, including medial prefrontal cortex, dorsolateral prefrontal cortex and right temporoparietal junction. However, the temporal characteristics of the trustor’s decision-making and outcome evaluation during the Trust Game are still unclear. We aim to address this limitation and understand the cognitive and biological mechanisms underlying decisions to trust. In the current study, we employed the event-related potentials (ERPs) technology to record 20 healthy participants’ electrical brain activity while they played the role of trustor in a repeated Trust Game. During this game, participants made decisions to trust or not to trust a same counterpart over 150 trials. The counterpart’s reciprocation strategy was manipulated by the experimenter (50% reinforcement rate). Participants were provided with post-decision feedback about the outcome of their decisions (gain or loss game points) in each trial. The behavioral data and ERP component in the decision phase and the outcome evaluation phase were analyzed. Behavioral results revealed that participants made trusting decisions more often than chance. Electrophysiological results found that the peak amplitudes of P2 for distrusting choice were significantly larger than trusting choice in the decision phase. The neural activity in the P2 time window that differentiated between distrusting and trusting choices was potentially generated in the middle frontal gyrus and the inferior frontal gyrus. In the outcome phase, the feedback-related negativity (FRN) was more negative going in response to loss feedback compared to gain feedback, while P300 latency was shorter in response to gain feedback than in response to loss feedback. Our data provide some insights into the psychophysiological processes underlying human’s trust decision-making for the repeated social interactions. Specifically, in the decision phase, distrusting choice induced a larger P2 than did trusting choice, which may reflect conflict detection caused by the violation of injunctive norms of cooperation and trust. In the outcome evaluation phase, FRN was larger in response to loss feedback compared to gain feedback, which may indicate the violation of reward expectation associated with trusting decisions. These findings highlight the ingrained norm of cooperation and trust in modern society, and reveal some temporal characteristics of the trustor’s decision making and outcome evaluation processes in the repeated trust game.

Key words: Trust game, decision-making, outcome evaluation, P2, feedback related negativity, P300