Abundant evidence has revealed that social observation could enhance people's norm-enforcement behaviors to norm violators. However, whether such enhancement is strategically reputation-based without changes on awareness of social norms or it is accompanied with strengthened perception of norm violations remains unclear. We aimed to test these two hypotheses using a modified Ultimatum Game (UG). Participants played the UG as responders in the fMRI scanner after being instructed the rules of the game and how the observers monitored their performances during the task. Behavioral results showed that unfair offers were perceived more unfair (decreased fairness ratings) and rejected more often under the condition with social observation than that without observation (the control condition). The changes in fairness ratings predicted the increase of rejection rates between two conditions, which provided more evidence for the latter hypothesis. Neural results demonstrated that right insula and anterior cingulate cortex associated with processing norm violations and/or negative emotions were more activated in response to unfair treatments under social observation relative to the control condition. Furthermore, bilateral anterior insula, anterior cingulate cortex, and right amygdala (an emotional processing structure) showed increased activations with the reduction of fairness ratings under social observation. Besides, compared to the control condition, rejecting unfair trials under social observation induced more left anterior insula activation. These findings indicated that the increase of norm-enforcement behaviors in the UG under social observation was more than a behavioral strategy for social desirability, but a result of enhanced sensitivity to fairness norm violations and unfairness-related negative feelings.

中文翻译：

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社会观察下的标准执行行为的认知和神经机制。

大量证据表明，社会观察可以增强人们的规范执行行为，以违反规范。但是，尚不清楚这种增强是否在战略上基于声誉，而不改变对社会规范的认识，还是伴随着对违反规范的增强认识。我们旨在使用改良的《最后通Game博弈》（UG）检验这两个假设。在被告知游戏规则以及观察者如何在任务执行过程中监控其表现之后，参与者在fMRI扫描器中扮演UG的响应者角色。行为结果表明，在有社会观察的条件下，与没有观察的条件（对照条件）相比，不公平的提议被认为更不公平（公平等级降低）并且被拒绝的可能性更高。公平性评级的变化预示了两种情况之间的拒绝率增加，这为后一种假设提供了更多证据。神经结果表明，在社交观察下，相对于对照条件，与加工规范违规和/或负面情绪相关的右岛和前扣带回皮层被激活得更多。此外，在社会观察下，双侧前岛岛，前扣带回皮层和右杏仁核（一种情感处理结构）显示出增加的激活，同时降低了公平性等级。此外，与对照组相比，在社会观察下拒绝不公平的试验会导致更多的左前岛支激活。