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.
"So we all believed the intelligence."
"The United Kingdom and other nations believed in the intelligence. the principal presenter of the case may carry a great burden, when it turned out that so much of it was flawed. It was a single-sourced and a very unreliable that we should have been aware."
Classified document didn't help proper understanding of the war to come, the loss of life, and destruction of families. (Elise Amendola/AP.)