Don't judge a book by its cover: The effect of perceived facial trustworthiness on advice following in the context of value-based decision-making

Trustworthiness is crucial in social interactions that depend on other's information. For example, an interaction partner's trustworthiness determines whose advice we act on in learning contexts, whom we choose to invest in during economic decisions, or even whom we decide to cooperate with. However, how perceived trustworthiness influences advice following in value-based decision-making when the trustworthiness manipulation is independent of the quality of the advice remains poorly understood. In two experiments, participants played a modified version of The Door Game, selecting one out of two doors to find a reward based on advisor's advice. The advisors were computer-generated faces categorised as trustworthy or untrustworthy, with identical advice validity (66 %). In Experiment 1 (N = 124), participants initially followed advice from perceived trustworthy advisors more frequently, but this effect disappeared by the end of the experiment. In our preregistered replication (Experiment 2, N = 300), we observed a similar pattern, confirming the findings of Experiment 1. In a third preregistered experiment (N = 85), participants rated the trustworthiness of each face. We used these ratings as an independent variable to reanalyse the advice following rates from Experiments 1 and 2. The results were identical as with our categorical analyses. Moreover, a mediation analysis revealed that trustworthiness ratings mediated the relationship between perceived trustworthiness and advice following. Overall, our findings underscore the importance of social information such as perceived trustworthiness in value-based decision-making and its dynamic nature, which is potentially explained by changes in the decision-making strategy, or by rapid adjustments of our trust beliefs.