ISSN 0439-755X
CN 11-1911/B

Acta Psychologica Sinica ›› 2023, Vol. 55 ›› Issue (11): 1859-1871.doi: 10.3724/SP.J.1041.2023.01859

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Influence of social distance and promise levels on trust decisions: An ERPs study

LI Mei1,2,3, LI Jin2,3, ZHANG Guanfei2,3, ZHONG Yiping2,3(), LI Hong1()   

  1. 1Center for Studies of Psychological Application; South China Normal University; Guangzhou 510631, China
    2Department of Psychology, Hunan Normal University, Changsha 410081, China
    3Cognition and Human Behavior Key Laboratory of Hunan Province, Changsha 410081, China
  • Received:2022-09-22 Published:2023-11-25 Online:2023-08-31
  • Contact: ZHONG Yiping,LI Hong;


Previous research has revealed that trust plays an important role in promoting functioning, economic growth, and individual well-being in human society. Trust refers to individuals’ willingness to take risks to hand over their resources to others in the context of social uncertainty. Based on rational signal theory, individuals tend to make social decisions (e.g., trust) according to perceived social information of others, such as social identity, gestures, language, and behaviors. Among these, trustees’ social identity and their promises are important social information that convey whether an individual is trustworthy and reliable. Previous research has only examined the effect of promise levels on trust decisions, or the effect social distance on trust decisions. However, little is known about how promise levels and social distance interact to affect trust behaviors and its neural mechanisms.

We adapted a Trust Game (TG) and the event-related potentials (ERPs) to examine the neurocognitive mechanisms of the effect of promise levels and social distance on trust behaviors. In particular, participates were asked to choose whether to trust their friends and strangers when they made high and low-level promises while electroencephalograms (EEGs) were recorded. Within each round, participants were informed of the promisor and their promise. We adopted two promise levels from previous studies: high-level promises would return 28 yuan (70%), and low-level 12 yuan (30%). The social distance includes both friend and stranger levels. The experiment consisted of 600 trials, including 150 trials for each condition.

These results suggest that motivations of trust behaviors toward friends and strangers are driven by different psychological mechanisms. Individuals trust friends more, and when the promisor is a friend, individuals can be motivated by the mutual interests of self and friends when making trust choices. However, when the promisor is a stranger, individuals are only driven by self-interest, and they do not care about strangers’ benefits when making trust choices. The present study provides insight into how the brain processes the interplay of social distance and promise levels on trust decisions, which broadens the previous insight into understanding trust behaviors.

Key words: promise levels, social distance, trust behavior, rational signal theory, event-related potentials (ERPs)