[Photographic face recognition of cooperators vs. defectors]

Results of three experiments, in which a total of 167 students participated, consistently indicated that participants performed recognition tasks better for face photographs of defectors than those of cooperators. The face photographs used in the experiments were those of participants taken during prisoner's dilemma (PD) experiments a few years prior to the present study. In Experiments 1 and 2, photographs of cooperators and defectors in a one-shot PD experiment, taken after they had filled out a lengthy post-experimental questionnaire, were used. In Experiment 3, the photographs were those of high and low cooperators, taken at the moment of a cooperation or defection choice, respectively. Recognition was better for photographs that were judged unattractive than attractive. At the same time, it was better for photographs of less cooperative participants in the PD studies than those of more cooperative participants. Implications of the findings for Cosmides & Tooby's (1992) 'cheater-detection' module for social exchange domain were discussed.