Confirmation Bias
Confirmation Bias
Confirmation bias is the tendency to search for, favour, interpret, and remember information in a way that confirms one's existing beliefs or hypotheses. Rather than evaluating evidence objectively, people unconsciously filter it through the lens of what they already believe. This process makes people resistant to changing their minds even when contradictory evidence is available.
Confirmation bias is closely linked to Schema Theory, as people use their existing schemas to interpret new information. Schemas act as filters — information that fits an existing schema is absorbed easily and remembered well, while information that contradicts it is often dismissed, reinterpreted, or simply ignored. This makes confirmation bias a natural outcome of how schemas function in everyday cognition.
Key Research: Wason Selection Task (1968)
Peter Wason designed the Wason Selection Task to study logical reasoning and uncovered strong evidence for confirmation bias. Participants were shown four cards showing D, K, 3, and 7, and told a rule: if a card shows a vowel on one side, it must show an even number on the other. They were asked which cards to turn over to test the rule. The logically correct answer is to turn over D (to check if the other side has an even number) and 7 (to check if there is a vowel on the other side). However, most participants chose D and 3 — they sought to confirm the rule rather than falsify it. Turning over 3 is irrelevant because finding a consonant on the other side neither confirms nor disconfirms the rule. This reveals confirmation bias in logical reasoning.
Confirmation Bias and Stereotypes: Confirmation bias has particularly important social consequences. It strengthens stereotypes by causing people to notice and remember information that fits their existing beliefs about a group, while overlooking contradictory examples. This self-reinforcing cycle makes stereotypes resistant to change even in the face of clear counter-evidence.
Evaluation: Confirmation bias research demonstrates consistent results across a wide range of tasks, including real-world decision-making. However, context matters — people show less confirmation bias when the stakes of a decision are high, when they are held accountable for their reasoning, or when they are experts in a domain. This suggests that confirmation bias is not inevitable but can be reduced with deliberate, motivated effort. The Wason task specifically tests formal logical reasoning, which may differ from everyday belief formation and updating, so its direct applicability to real-world confirmation bias should be treated cautiously.