Social factors can affect the processing of intertemporal choice, but the influence of social distance on the rewarding process of intertemporal choice is unclear. Therefore, by designing a novel cognitive resource competition paradigm for undifferentiated intertemporal choice, this article aims to explore the influence of social distance on intertemporal choice reward processing at the electrophysiological level. It was found that compared with stranger, P3a is greater for friend, which means social distance is evaluated in the early stage. In addition, different brain regions in the early stages are taking charge of processing the soon-but-small (SS) and later-but-lager (LL) reward in intertemporal choice. There is an interaction effect between social distance (friend vs. stranger) and intertemporal choice (SS reward vs. LL reward) on P3b. Under friend condition, the P3b induced by LL reward is more positive than SS reward. Under the condition of choosing the LL reward, the P3b induced by friend is more positive than stranger. This result shows that in the latter stage of reward processing, the evaluation process of time discounting is less sensitive in LL reward for friend caused by lack of cognitive resources which is occupied when dealing with social distance in advance, and thus the degree of time discount was reduced. These findings demonstrate that P3b is the key index of time discounting and immediate and delayed rewards are valued in different brain regions.

中文翻译：

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社会距离对奖励处理的跨期选择的影响：一项与事件相关的潜力研究

社会因素会影响跨期选择的过程，但社会距离对跨期选择奖励过程的影响尚不清楚。因此，本文旨在通过为无差异跨期选择设计一种新的认知资源竞争范式，从电生理层面探讨社会距离对跨期选择奖励加工的影响。结果发现，与陌生人相比，朋友的P3a更大，这意味着在早期评估社交距离。此外，早期阶段的不同大脑区域负责处理跨期选择中的“很快但很小”（SS）和“稍后但很长时间”（LL）的奖励。P3b 上的社交距离（朋友 vs. 陌生人）和跨期选择（SS 奖励 vs. LL 奖励）之间存在交互作用。在朋友条件下，LL 奖励引起的 P3b 比 SS 奖励更积极。在选择LL奖励的情况下，朋友诱导的P3b比陌生人更积极。该结果表明，在奖励处理的后期，由于缺乏认知资源而导致朋友的LL奖励在提前处理社交距离时，时间折扣的评估过程不太敏感，从而导致时间折扣的程度被减少了。这些发现表明 P3b 是时间折扣的关键指标，即时和延迟奖励在不同的大脑区域中受到重视。该结果表明，在奖励处理的后期，由于缺乏认知资源而导致朋友的LL奖励在提前处理社交距离时，时间折扣的评估过程不太敏感，从而导致时间折扣的程度被减少了。这些发现表明 P3b 是时间折扣的关键指标，即时和延迟奖励在不同的大脑区域中受到重视。该结果表明，在奖励处理的后期，由于缺乏认知资源而导致朋友的LL奖励在提前处理社交距离时，时间折扣的评估过程不太敏感，从而导致时间折扣的程度被减少了。这些发现表明 P3b 是时间折扣的关键指标，即时和延迟奖励在不同的大脑区域中受到重视。