Do people assimilate new information in an efficient and unbiased manner; that is, do they update prior beliefs in accordance with Bayes’ rule? Or are they selective in the way that they gather and absorb new information? Although many classic studies in political science and psychology contend that people resist discordant information, more recent research has tended to call the selective perception hypothesis into question. This paper synthesizes the literatures on biased assimilation and belief polarization using a formal model that encompasses both Bayesian and biased learning. The analysis reveals (a) the conditions under which these phenomena may be consistent with Bayesian learning, (b) the methodological inadequacy of certain research designs that fail to control for preferences or prior information, and (c) the limited support that exists for the more extreme variants of the selective perception hypothesis.
