Confirmation Bias

Confirmation bias is a tendency for people to confirm their preconceptions or hypotheses, independently of whether or not they are true. People can reinforce their existing attitudes by selectively collecting new evidence, by interpreting evidence in a biased way or by selectively recalling information from memory.

This is demonstrated in how people tend to test hypotheses in a one-sided way, focusing on one possibility and neglecting alternatives. They frame questions in such a way that a "yes" answer supports their hypothesis, and do not test for information that would refute their hypothesis.

The bias appears in particular for issues that are emotionally significant (including some personal and political topics) and for established beliefs which shape the individual's expectations.

Students are encouraged to add examples of this type of bias.

1. Confirmation bias. (2009, December 5). In Wikipedia, the free encyclopedia. Retrieved December 12, 2009 from
2. Oswald, M. E., Grosjean, S.(2004), Confirmation bias, Cognitive illusions: A handbook on fallacies and biases in thinking, judgement and memory (pp. 79–96). Hove, UK: Psychology Press, Oswald & Grosjean.
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