Experimental evidence on rational inattention

We show that rational inattention theory of Sims (2003) provides a rationalization of choice models à la Luce and gives a structural interpretation to probability curvature parameters as reflecting costs of processing information. We use data from a behavioral experiment to show that people behave according to predictions of the theory. We estimate attitudes to risk and costs of information for individual participants and document overwhelming heterogeneity in these parameters among a relatively homogeneous sample of people. We characterize, both theoretically and empirically, the aggregation biases this heterogeneity implies and find these biases to be substantial.