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People’s appearance and behaviors in strategic interactions provide a variety of informative clues that can help people accurately predict beliefs, intentions, and future behaviors. Mind reading mechanisms may have been selected for that allow for better-than-chance prediction of others’ strategic social propensities based on the sparse information available when forming first and second impressions. We hypothesize that first impressions are based on prior beliefs and available information gleaned from another’s description and appearance. For example, where another’s gender is identified, prior gender stereotypes could influence expectations and correct guesses about them. We also hypothesize that mind reading mechanisms use second impressions to predict behavior: using new knowledge of past behaviors to predict future behavior. For example, knowledge of the last round behaviors in a repeated strategic interaction should improve the accuracy of guesses about the next round behavior. We conducted a two-part study to test our predictive mind reading hypotheses and to evaluate evidence of accurate cheater and cooperator detection. First, across multiple rounds of play between matched partners, we recorded thin slice videos of university students just prior to their choices in a repeated Prisoner’s Dilemma. Subsequently, a worldwide sample of raters recruited online evaluated either thin-slice videos, photo stills from the videos, no images with gender labeled, or no images with gender blinded for each target. Raters guessed players’ Prisoner’s Dilemma choices in the first round, and, again, in the second round after viewing first round behavior histories. Indicative of mindreading: in all treatments where targets are seen, or their gender is labeled, or their behavioral history is provided, raters guess unacquainted players’ behavior with above-chance accuracy. Overall, cooperators are more accurately detected than cheaters. In both rounds, both cooperator and cheater detection are significantly more accurate when players’ photo or video are seen, where their gender is revealed by image or label, and under conditions with behavioral history. These results provide supporting evidence for predictive mind reading abilities that people use to efficiently detect cooperators and cheaters with better-than-chance accuracy under sparse information conditions. This ability to apply and hone predictive mindreading may help explain why cooperation is commonly observed among strangers in everyday social dilemmas.


ESI Working Paper 22-19



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