We aim to understand the role and evolution of beliefs in the indefinitely repeated prisoner's dilemma (IRPD). To do so, we elicit beliefs about the supergame strategies chosen by others. We find that heterogeneity in beliefs and changes in beliefs with experience are central to understanding...

Why do individuals interpret the same information differently? We propose that individuals follow Bayes' Rule when forming posteriors with one exception: when assessing the credibility of experts, they "double-dip" the data and use already-updated beliefs instead of their priors. Our proposed...