Disconfirmation Bias: Definition, Theory & Example

Instructor: Maria Airth

Maria has a Doctorate of Education and over 20 years of experience teaching psychology and math related courses at the university level.

When a person believes something so strongly they have difficulty accepting any evidence to the contrary it is called disconfirmation bias. This lesson reviews disconfirmation bias and explores examples and theories connected to it.

Disconfirmation Bias

'You must have your facts wrong because what I heard about the issue was very different from that.'

'See, I told you I was right. This article proves it.'

These two statements are examples of a person who is rooted in their preconceived ideas and beliefs. The person has a strong investment in maintaining their opinion and will resist information that might lead them to reassess these opinions. Any information that supports the person's current beliefs is deemed accurate with little or no critical review.

This is known as disconfirmation bias, when a person is more likely to accept information that supports previously held beliefs and more likely to dismiss information that refutes previously held beliefs.


Disconfirmation bias is an important psychological concept because it has a strong effect on society as a whole and each of us individually. Due to disconfirmation bias, people are generally less likely to accurately and fairly evaluate arguments that deviate from their previously held ideas.

Why is this a big deal? If we are incapable of truly evaluating the merits of others' arguments, we may never be able to enter true collaboration and compromise scenarios. Fair evaluation of arguments that differ from our own is often the only way to come to agreements and progress from conflict. Progress demands that people are able to set aside prior beliefs and come to new conclusions. Compromise requires that people are capable of truly investing in new thoughts and ways of doing things without maintaining feelings of doubt in the new methods.

Cognitive dissonance is the phenomenon which stems from maintaining conflicting thoughts. It is an uncomfortable feeling that can lead to severe mental distress depending on the level of dissonance created. Sometimes disconfirmation bias can be caused by an unconscious need to avoid cognitive dissonance.

Examples of Disconfirmation Bias

Imagine that you have been told all your life that your ancestors were from a certain country, and you built an identity around being descended from this culture. The culture of that country defined you. Then, one day, you had the opportunity to take a genetic ancestry test and it showed that you were really descended from a different part of the world. To make matters worse, the DNA showed that your ancestors were really the long-time rivals of those that you thought were your ancestors.

In this scenario, you would have to choose whether to believe the DNA results or not. If you were to choose to believe them, then you would experience severe cognitive dissonance due to your long held identity being connected to the wrong culture. To avoid that uncomfortable feeling of having to rearrange your thoughts and identity, you might choose, instead, to disbelieve the test results and claim they are wrong. This is disconfirmation bias. Information has been presented that does not match a person's previously held beliefs so the person does not accept the information as being accurate.

Other examples of disconfirmation bias can be seen during any election season. Once people have established their opinion on any particular issue, they are more likely to fully accept articles and information that support their belief while calling into question the accuracy of any article or information that challenges their position. This is so common that another psychological phenomenon has been identified from it; the hostile media effect is the belief that the media is actively biased against your beliefs when you are presented with media material that challenges those beliefs.

Defense Against Disconfirmation Bias

Disconfirmation bias can be incredibly powerful and influential to some individuals and thus is difficult to defend against. However, it is important to understand that it does exist and be willing to patiently work to break through it if you are debating a contentious issue.

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