Robust Information Transmission

This paper investigates robust information transmission between a sender and a receiver in the Crawford and Sobel (1982) model. We characterize behavior that remains equilibrium behavior inde-pendently of the form of a small communication cost. Under stan-dard conditions, we find that an equilibrium outcome is robust if and only if it features a maximal number of on-path actions and each is induced by a single message. The result extends regardless of the direction of the bias, the number of available messages, or whether the objectives of the sender and the receiver are aligned. (JEL D82, D83)