Abstract: Trust refers to the beliefs about whether other people behave opportunistically in social and economic interactions. In terms of the rational signal theory, a person often makes social decisions (e.g. trust) based on perceived social information of others, such as language, gestures, and behaviors. Thus, people tend to make promises in order to convey social information that they are trustworthy and reliable. However, promises are characteristic of non-enforcement and non-binding, which may result in betrayal or deception. Previous studies found promises (vs non-promises) lead to more trust behaviors, however, it still remains unclear how promise levels impact trust decisions and what is the mechanism underlying this process. Therefore, the present study aimed to investigate the impact of promise levels on trust decisions. Next, we tested the mediation effect of cheating notion in the prediction of promise levels on trust behaviors. In order to test effects of promise levels on trust decisions, the current research conducted two studies using an adapted Trust Game (TG). In study 1, we recruited 46 college students who played as trustors completing 30 one-shot TG tasks with anonymous partners. Within each round, participants were informed the partner’s promise. The current study adopted three promise levels from previous studies: the high-level promises will return 14 yuan (70%), medium-level 10 yuan (50%), and low-level 6 yuan (30%). Next, they were allowed to decide whether to invest to their partners, then reported their social expectation for the anonymous partner. The results showed that participants were less likely to invest when they were informed high-level promises instead of medium- or low-level promises, suggesting high level promises inhibited trust decisions. In study 2, there were 28 college students participated in the similar experiment as study 1. Within this study, participants were additionally required to report the possibility of being deceived by their partners, which were regarded as indicators of cheating notion. The results not only consistently demonstrated the findings of study 1, but also found the cheating notion mediated the impacts of promise levels on trust decisions. Specifically, people perceived more cheating notion if their partner promised large payoffs rather than small or medium payoffs, thus resulted in distrust decisions. The present findings suggested cheating notion was critical in understanding the relationships between promise levels and trust decisions. In conclusion, people tend to trust the partners who promised small or medium payoffs instead of large payoffs. Given the non-binding nature of promises, individuals who promised large payoffs were more likely to deceive compared to people promised small or medium payoffs. Therefore, promises levels predicted trust behaviors through the mediation of cheating notion. The present study extended the previous findings by showing the impacts of promises levels on trust decisions, as well as the mediation effect of cheating notion underlying its process.

Key words: promise levels, trust decisions, cheating notion, rational signal theory

摘要： 基于合理信号理论，承诺在社会互动中传递可信性信号，影响信任决策。本研究通过两个实验，分析了74名被试在信任博弈任务中的决策差异，考察了不同承诺水平下（低、中、高）的信任决策，以及感知被骗预期的中介作用。结果表明，相比中、低水平承诺，高水平承诺会抑制信任行为及信任认知。此外，被骗预期作为中介变量，发现高水平承诺预测较高被骗预期，从而抑制了信任选择。综上，本研究发现承诺水平通过被骗预期影响信任决策。

关键词: 承诺水平, 信任决策, 被骗预期, 合理信号理论