Confirmation Bias Emerges from an Approximation to Bayesian Reasoning

Abstract

Confirmation bias is defined as searching for and assimilating information in a way that favours existing beliefs. We show that confirmation bias is a natural consequence of boundedly rational belief updating by presenting the BIASR model (Bayesian updating with an Independence Approximation and Source Reliability). Upon receiving information, an individual updates beliefs about the hypothesis in question and the reliability of the information source simultaneously. In this model, an individual's beliefs about a hypothesis and the source reliability form a Bayesian network. This rational updating introduces numerous dependencies between beliefs, the tracking of which represents an unrealistic demand on memory. Our model takes this into account by including realistic cognitive limitations proposed in prior research. Specifically, human cognition can overcome this memory limitation by assuming independence between beliefs. We show how a Bayesian belief updating model incorporating this independence approximation generates many types of confirmation bias, including biased evaluation, biased assimilation, attitude polarisation, belief perseverance and confirmation bias in the selection of sources.

Cognitive Economics: Minds and Markets as Complex Systems

“…Space prohibits us from detailed discussion of several other nascent approaches sharing a philosophical kinship. For example, resource rationality models [105][106] simultaneously demonstrate the rational basis of seemingly irrational behaviors (complementing ecological rationality approaches [20]) while formalizing the "mind-as-market" notion that minds must ration scarce cognitive resources. Virtual bargaining models [107][108] use the idea that in the absence of communication, people often act as though they had struck an explicit bargain, providing cognitive grounding for social behavior.…”