Disconfirmation bias refers to the tendency for people to extend critical scrutiny to information which contradicts their prior beliefs and accept uncritically information that is congruent with their prior beliefs.

This cognitive bias is closely related to confirmation bias, which is the tendency to simply avoid "counter-attitudinal" new information. When exactly each applies is not yet well understood.

One study found that students told that they tested positive for a medical condition scrutinized the report more carefully. At the same time, those students said they thought the condition was less dangerous and more common than students who were not told they had the condition.

In an earlier study by Lord , Ross and Lepper, 24 pro-death penalty students and 24 anti-death penalty students critically evaluated "studies" on capital punishment. These students found that studies which supported their pre-existing view were superior to those which contradicted it, in a number of detailed and specific ways. In fact, the studies all described the same experimental procedure but with only the purported result changed.

The hostile media effect may be the results of disconfirmation bias.

See also: list of cognitive biases.

References

• Ditto, P. H., & Lopez, D. F. (1992). Motivated skepticism: Use of differential decision criteria for preferred and non-preferred conclusions. Journal of Personality and Social Psychology, 63, 568-584.
• Edwards K. & Smith E. E. (1996). A disconfirmation bias in the evaluation of arguments. Journal of Personality and Social Psychology, 71, 5-24.
• Lord, C., Ross, L., & Lepper, M. (1979). Biased Assimilation and Attitude Polarization: The effects of Prior Theories on Subsequently Considered Evidence. Journal of Personality and Social Psychology, 37, 2098-2109. (summary here)