The paper "First Impressions Matter: A Model of Confirmatory Bias" by Matthew Rabin and Joel Schrag explores the cognitive bias known as confirmatory bias, where individuals tend to misinterpret new information as supporting their pre-existing hypotheses. The authors model this bias in a symmetric framework where exactly one of two hypotheses is true. They show that confirmatory bias leads to overconfidence, meaning that individuals tend to believe more strongly than they should in their favored hypotheses. The model also reveals surprising results, such as the possibility of an agent eventually believing with near certainty in a false hypothesis even after receiving an infinite amount of information, if the bias is strong enough. The authors discuss the implications of these findings in multi-person economic situations and highlight the challenges of incorporating such biases into economic analysis. The paper is based on psychological research and provides a formal framework to understand how confirmatory bias affects belief formation and decision-making.The paper "First Impressions Matter: A Model of Confirmatory Bias" by Matthew Rabin and Joel Schrag explores the cognitive bias known as confirmatory bias, where individuals tend to misinterpret new information as supporting their pre-existing hypotheses. The authors model this bias in a symmetric framework where exactly one of two hypotheses is true. They show that confirmatory bias leads to overconfidence, meaning that individuals tend to believe more strongly than they should in their favored hypotheses. The model also reveals surprising results, such as the possibility of an agent eventually believing with near certainty in a false hypothesis even after receiving an infinite amount of information, if the bias is strong enough. The authors discuss the implications of these findings in multi-person economic situations and highlight the challenges of incorporating such biases into economic analysis. The paper is based on psychological research and provides a formal framework to understand how confirmatory bias affects belief formation and decision-making.