Confirmation bias

Confirmation bias (also confirmatory bias, myside bias,^[a] or congeniality bias^[2]) is the tendency to search for, interpret, favor, and recall information in a way that confirms or supports one's prior beliefs or values.^[3] People display this bias when they select information that supports their views, ignoring contrary information, or when they interpret ambiguous evidence as supporting their existing attitudes. The effect is strongest for desired outcomes, for emotionally charged issues, and for deeply entrenched beliefs. Confirmation bias is insuperable for most people, but they can manage it, for example, by education and training in critical thinking skills.

Biased search for information, biased interpretation of this information, and biased memory recall, have been invoked to explain four specific effects:

1. attitude polarization (when a disagreement becomes more extreme even though the different parties are exposed to the same evidence)
2. belief perseverance (when beliefs persist after the evidence for them is shown to be false)
3. the irrational primacy effect (a greater reliance on information encountered early in a series)
4. illusory correlation (when people falsely perceive an association between two events or situations).

A series of psychological experiments in the 1960s suggested that people are biased toward confirming their existing beliefs. Later work re-interpreted these results as a tendency to test ideas in a one-sided way, focusing on one possibility and ignoring alternatives. Explanations for the observed biases include wishful thinking and the limited human capacity to process information. Another proposal is that people show confirmation bias because they are pragmatically assessing the costs of being wrong, rather than investigating in a neutral, scientific way.

Flawed decisions due to confirmation bias have been found in a wide range of political, organizational, financial and scientific contexts. These biases contribute to overconfidence in personal beliefs and can maintain or strengthen beliefs in the face of contrary evidence. For example, confirmation bias produces systematic errors in scientific research based on inductive reasoning (the gradual accumulation of supportive evidence). Similarly, a police detective may identify a suspect early in an investigation, but then may only seek confirming rather than disconfirming evidence. A medical practitioner may prematurely focus on a particular disorder early in a diagnostic session, and then seek only confirming evidence. In social media, confirmation bias is amplified by the use of filter bubbles, or "algorithmic editing", which display to individuals only information they are likely to agree with, while excluding opposing views.

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