Confirmation bias is the tendency to search for, interpret, favor, and recall information in a way that confirms or supports one's prior beliefs or values. 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 cannot be eliminated entirely, but it can be managed, for example, by education and training in critical thinking skills.

Confirmation bias is a broad construct covering a number of explanations. 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); and 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 (myside bias, an alternative name for confirmation bias). In general, current explanations for the observed biases reveal the limited human capacity to process the complete set of information available, leading to a failure to investigate in a neutral, scientific way.

Flawed decisions due to confirmation bias have been found in 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.

 

Note:   The above text is excerpted from the Wikipedia article Confirmation bias, which has been released under the GNU Free Documentation License.