The capacity to trust wisely is a critical facilitator of success and prosperity, and it has been conjectured that people of higher intelligence were better able to detect signs of untrustworthiness from potential partners. In contrast, this article reports five Trust Game studies suggesting that reading trustworthiness on the faces of strangers is a modular process. Trustworthiness detection from faces is independent of general intelligence (Study 1) and effortless (Study 2). Pictures that include non-facial features such as hair and clothing impair trustworthiness detection (Study 3) by increasing reliance on conscious judgments (Study 4), but people largely prefer to make decisions from this sort of pictures (Study 5). In sum, trustworthiness detection in an economic interaction is a genuine and effortless ability, possessed in equal amount by people of all cognitive capacities, but whose impenetrability leads to inaccurate conscious judgments and inappropriate informational preferences.
TSE Working Paper, n. 12-311, May 2012