Confirmation bias is an irrational tendency to search for, interpret or remember information in a way that confirms one’s preconceptions or working hypotheses. It is a type of cognitive bias and a systematic error of inductive reasoning. These biases in information processing are distinguished from the behavioral confirmation effect (also called self-fulfilling prophecy), in which a person’s expectations influence their own behavior.
Biases can occur in the collection, interpretation or recall of information. Some psychologists use “confirmation bias” for systematic biases in any of these three processes, while others restrict the term to selective collection of evidence, using “assimilation bias” for biased interpretation. In many reasoning situations, people avoid confirmation bias and test hypotheses in a genuinely informative way. The bias appears in particular for issues that are emotionally significant (such as personal health or relationships) and for established beliefs which shape the individual’s expectations. Biased search, interpretation and/or storage have been invoked to explain belief perseverance (a well-established finding that beliefs remain when the evidence for them is taken away) and attitude polarization (when a disagreement becomes more polarized as the different parties are exposed to the same evidence).
Confirmation bias can lead to disastrous decisions, especially in organizational, military and political contexts. Attempts to teach critical thinking can be counter-productive if confirmation biases are not addressed, since by applying logical thinking only to one side of an argument, thinkers can become “actively closed-minded”.