Abstract: Third-party punishment refers to the phenomenon that individuals sacrifice their own interests to punish the violators when the violation has nothing to do with their own interests (Fehr & Fischbacher, 2004b). As a typical moral behavior, it follows the moral principles advocated by the society. But in the real world, it happens occasionally. Lerner and others put forward the belief in a just world theory to explain these phenomena (Lerner & Miller, 1978). Belief in a just world is the belief that people need to believe that the world they live in is a just and orderly world in which they get what they deserve and what they get. Researchers found that although the belief in the just world as the motivation of individuals is reflected in everyone, there are great differences in individuals' belief in the just world, which leads to great differences in behaviors between individuals. At present, there are relatively few studies have explored the impact of the belief in a just world on third-party punishment from the perspective of individual differences. This study will explore the impact of the belief in the just world on third-party punishment. In addition, in the ERP study of third-party punishment, MFN and P300 are the two most common eeg components. Up to now, the neural mechanism of justice and third-party punishment has been studied. Belief in a just world, as a subjective cognition of justice, is still lack of research on the neural mechanism of third-party punishment. Based on this, it is necessary to study the neural mechanism of belief in a just world affecting third-party punishment. The Personal Belief in a Just World Scale was used to test 83 college students. After removing invalid data, the score results were ranked from high to low, with 27% of the subjects in the top score as high belief in a just world group, and 27% of the subjects in the bottom score as low belief in a just world group. Finally there were 36 subjects, 18 of whom were in the high belief in a just world group, 18 of whom were in the low belief in a just world group. We administered a modified version of the third-party punishment task, in which participants made a choice between changing or not changing. This study recorded and analyzed the differences among the components of ERP in the third party punishment task, so as to explore the neural mechanism of the influence of belief in a just world on the third-party punishment. The behavioral results show that the third-party punishment of individuals with high belief in a just world is significantly higher than that of individuals with low belief in a just world, and the third-party punishment of individuals with high belief in a just world has no difference under high and low injustice proposal, while the third- party punishment of individuals with low belief in a just world is significantly more under injustice proposal. The ERP results show that individuals with high belief in a just world induced larger MFN amplitude and smaller P300 amplitude than individuals with low belief in a just world, and there is no difference in the MFN amplitude of individuals with high belief in a just world under high and low injustice proposal, while the MFN amplitude of individuals with low belief in a just world under high injustice proposal is significantly larger. In conclusion, the present study found that compared with individuals with low belief in the just world, individuals with high belief in the just world have strong and stable cognition of justice, they make third-party punishment more based on their own expectation of the just result rather than external conditions.

Key words: belief in a just world, third party punishment, ERP

摘要： 采用事件相关电位技术（ERP）考察公正世界信念对第三方惩罚的影响。（1）行为结果显示，高公正世界信念个体的第三方惩罚显著多于低公正世界信念个体，低公正世界信念个体在高不公正提议下的第三方惩罚显著增加；（2）ERP结果显示，高公正世界信念个体比低公正世界信念个体诱发了更大的MFN波幅和更小的P300波幅，且高公正世界信念个体的MFN波幅在高、低不公正提议下没有差异，低公正世界信念个体在高不公正提议下的MFN波幅明显更大。这说明相比低公正世界信念个体，高公正世界信念个体所持有的公正认知强烈且稳定，个体做出第三方惩罚更多基于自身对于公正结果的预期，而非外部条件。

关键词: 公正世界信念, 第三方惩罚, ERP