群体身份调节最后通牒博弈的公平关注

Group Membership Modulates The Recipient's Fairness Consideration in Ultimatum Game

群际互动是社会互动的一种重要形式,在人类社会发展中起着重要作用。已有的行为研究表明个体参与群际互动时,互动对象的群体身份会影响其心理加工和行为决策。但目前关于群体身份如何影响公平加工的动态时间过程尚不清楚。为了研究群体身份对最后通牒任务(Ultimatum Game,UG)中反应者公平关注的影响,15名健康成人作为反应者与组内和组外提议者进行UG博弈,提议包括极端不公平、中等不公平或公平提议三种。事件相关电位结果发现,组外互动时公平提议和中等不公平提议比极端不公平提议诱发更负的AN1,组内互动时不同提议诱发的AN1无显著差异。来自组内成员的中等和极端不公平提议比公平提议引起更负的内侧额叶负波(MFN),但来自组外成员的不同提议则没有导致MFN波幅的变化。这些结果表明在群体互动情境下,互动成员的群体身份能够影响个体的早期注意资源分配和公平关注加工。

Intergroup interaction is a primary type of social interaction, and plays an important role in human social development. Previous behavioral researches based on economic game tasks has demonstrated that the perception of partner’s group membership could modulate individuals’ mental processes and behavioral decision making when the participants play the game against an ingroup or outgroup member. However, it is still unclear how group membership influences the time course of recipient’s fairness considerations in the asset allocation task. In order to address this problem, we use the Minimal Group Paradigm to manipulate the ingroup-outgroup distinction between subjects and interactive partner, and integrate Ultimatum Game task and event-related potentials （ERPs） technique to explore how group membership affect the processing of fairness process and the time course of evaluation to allocation proposal. Brain potentials were recorded while 15 healthy adult subjects participated as recipients in the Ultimatum Game with alleged members of both an experimentally induced ingroup and outgroup, and subjects would receive either extremely unfair, moderately unfair, or fair offers from proposers. The behavioral data and ERP amplitudes （AN1 and MFN） associated with the three offers in both two interactions were analyzed. The behavioral data suggested that participants accepted more offers from ingroup partner than from outgroup partner, and the acceptance rates for extremely and moderately unfair offers were higher when interacting with ingroup partner than with outgroup partner whereas it did not show difference for fair offers irrespective of ingroup or outgroup partner making the offers. The ERP results indicated that AN1 and MFN were not only influenced by offers’ fairness but also modulated by the group membership. The AN1 was more negative for fair and moderately unfair offers compared to extremely unfair offers when playing against an outgroup member whereas it did not show differential responses to different offers from ingroup partner. The MFN and MFN effect （dMFN） was more negative for extremely unfair offers compared to fair offers in the intergroup interaction whereas it did not show differential responses to different offers in the outgroup interaction. These results indicated that group membership influenced the early stage of outcome evaluation under asset distribution game. In the intergroup interaction, both group membership and offers’ fairness influence the early attention detection and resource allocation, which induced the larger AN1 for fair and moderately unfair offers from outgroup partner. Moreover, the perception of belonging to a social group increased the fair anticipation to ingroup partner and decreased the fair anticipation to outgroup partner, which may induce the larger MFN difference for unfair offers. The present study first demonstrates that group membership and offers’ fairness can modulate the process of attention allocation and fairness considerations.