Who judges a book by its cover? Belief in physiognomy and reliance on trustworthiness impressions from faces

People often rely on a person’s facial appearance when judging their trustworthiness, even when more diagnostic information is available. This can lead to worse decision outcomes and appearance-based discrimination. In three studies, we examine whether lay beliefs in physiognomy—the idea that facial features is indicative of a person’s character—can explain overreliance on trustworthiness impressions from faces. We find widespread endorsement of physiognomic beliefs in a representative sample of the Dutch population (Study 1, n = 2,624). Crucially, people with stronger physiognomic belief rely more on facial impressions when making trust decisions (Study 2, n = 224). They are also more confident in their ability to detect corrupt politicians based on facial photographs, even though this increased confidence is not associated with superior judgment accuracy (Study 3, n = 406). In sum, our studies show that physiognomic beliefs are widespread and related to overreliance on trustworthiness impressions from faces.