关键词: 信任形成, 联结学习, 刺激泛化, 行为意图, 漂移扩散模型

Abstract:

How do humans learn to trust unfamiliar others? Decisions in the absence of direct knowledge rely on our ability to generalize from past experiences and are often shaped by the degree of similarity between prior experience and novel situations. A previous study suggested that people use stimulus generalization from the same situation as a mechanism for learning to trust towards strangers. However, it is still unclear whether this stimulus generalization effect exists across different situations, and the role of intention perception in this effect. Here, we leverage a stimulus generalization framework to examine how perceptual similarity between known individuals and unfamiliar strangers across different interactive situations shapes people’s trust towards strangers. Given that the strong adaptability of the stimulus generalization mechanism, we assume that the faces associated with different degrees of unfairness will affect the individual's trust towards similar unfamiliar faces, and intention perception modulates this process.

Three experiments were conducted to examine the above hypothesis. In Experiment 1a and Experiment 1b, participants play or observe an iterative ultimatum game with three partners who exhibit highly unfair, medium unfair, or highly fair behavior. After learning who was the fair/unfair allocator, participants select new partners for a trust game. Unbeknownst to participants, each potential new partner was parametrically morphed with one of the three original players. In Experiment 2, participants play a similar iterative ultimatum game with three partners, nevertheless the allocations were generated by a computer algorithm which excludes the intention of the allocator.

A mixed linear regression was conducted, with both (un)fairness type (whether faces were morphed with the original fair, medium unfair, unfair allocator’ face) and perceptual similarity (increasing similarity to the original face, 23%, 34%, 45%, 56%, 67%, 78%) were entered as predictors of choosing to play with the morphed face. The result of Experiment 1a and Experiment 1b show that compared with the medium unfair condition, as the perceptual similarity between the morphed trustee’s face and the face of the fair (unfair) allocator in the previous interaction increases, the degree of trust (distrust) towards the trustee gradually increases. In addition, this effect is asymmetrical, participants preferentially avoided more the unfair morphs in comparison with the fair morphs. This suggests an asymmetric overgeneralization toward individuals perceived to be morally aversive. Using Drift-Diffusion Modeling (DDM), we found that the drift rate ν under unfair condition is significantly smaller than that under medium unfair or fair conditions, and most of them are in the range of less than 0. This suggests that individuals are more likely to accumulate evidence of distrust when making trust decisions about unfamiliar faces that are similar to the allocator who was unfair in previous interactions. In Experiment 2, under an unintentional situation, the above-mentioned cross-situational generalization effect disappeared.

Together, our results demonstrate that the individuals use the associative learning mechanism to capture the moral information of the interactive objects from the past experience, and then guides subsequent trust decision- making. This mechanism draws on prior learning to reduce the uncertainty associated with strangers, ultimately facilitating potentially adaptive decisions to trust, or withhold trust from unfamiliar others.

Key words: trust formation, associative learning, stimulus generalization, behavioral intention, Drift-Diffusion Modeling