Effects of sex and appearance on trust and trustworthiness

The ability to trust other individuals, including strangers, is a prerequisite for human cooperation. Economically it is not rational to trust others, as trust can be easily exploited. Still, generally the level of trust toward strangers is relatively high. Trust is closely related to trustworthiness: when trusting others, one expects them to reciprocate. Some individuals elicit more trust than others. Apparently, humans use subtle cues for judging the trustworthiness of their interaction partners. Here we report on an experiment that investigates trust and trustworthiness in a population of 176 mainly Dutch students. We address the following questions: What is the degree of trust and trustworthiness towards anonymous interaction partners? How do trust and trustworthiness change in a personalised setting (after seeing a silent video of a partner)? How does the sex and the facial features of the interaction partner affect trust and trustworthiness? The subjects in our experiment played a Trust Game that was shaped into a real-life story. The trustor was in the role of a farmer, who had to decide whether to entrust goods to a trustee, who in turn was in the role of a market seller. Trusting others could bring some extra profit to a trustor, but could also lead to loss of everything. The features of facial appearance were investigated with geometric morphometrics based on full-face photographs. Our results revealed that already under anonymous conditions the level of trust and trustworthiness was very high (70% of individuals trusted anonymous strangers). No sex differences between males and females were found in the anonymous setting. Under personalized conditions females elicited more trust than males in partners of the both sexes. Interestingly, females with more feminine facial shape elicited less trust in both male and female partners, while males with more masculine facial shape were more trusted by females, but less trusted by males. Neither gender nor facial femininity predicted actual trustworthiness of participants. Our results demonstrate that sex and appearance of interaction partners have a clear effect on eliciting trust in strangers. However, these cues do not seem to be reliable predictors of actual trustworthiness.