Title: Contracting with Unconscious Biases

Abstract: A principal and an agent have non-common priors on uncertainty in optimal contracting with moral hazard. I introduce an outside observer's belief considered as accurate to conduct objective welfare analysis. Without incentive provision, the two players' biases exhibit asymmetric effects on welfare. An overconfident (underconfident) agent is better-off if the principal is more overconfident (underconfident) than him. However, a biased principal not only benefits if the agent is more biased than him in the same direction, but also could be better-off if the agent biases towards a different direction. With incentive provision, only the agent's bias affects welfare. It costs a biased principal less as long as the agent is overconfident, while only an underconfident agent benefits.