How Confirmation Bias Works

Examples of confirmation bias

Verywell / Daniel Fishel 

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Where do your beliefs and opinions come from? If you're like most people, you feel that your convictions are rational, logical, and impartial, based on the result of years of experience and objective analysis of the information you have available.

In reality, all of us are susceptible to a tricky problem known as a confirmation bias. Our beliefs are often based on paying attention to the information that upholds them—while at the same time tending to ignore the information that challenges them.

Understanding Confirmation Bias

A confirmation bias is a type of cognitive bias that involves favoring information that confirms your previously existing beliefs or biases.

For example, imagine that a person holds a belief that left-handed people are more creative than right-handed people. Whenever this person encounters a person that is both left-handed and creative, they place greater importance on this "evidence" that supports what they already believe. This individual might even seek proof that further backs up this belief while discounting examples that don't support the idea.

Confirmation biases impact how we gather information, but they also influence how we interpret and recall information. For example, people who support or oppose a particular issue will not only seek information to support it, they will also interpret news stories in a way that upholds their existing ideas. They will also remember details in a way that reinforces these attitudes.

Confirmation Biases in Action

Consider the debate over gun control. Let's say Sally is in support of gun control. She seeks out news stories and opinion pieces that reaffirm the need for limitations on gun ownership. When she hears stories about shootings in the media, she interprets them in a way that supports her existing beliefs.

Henry, on the other hand, is adamantly opposed to gun control. He seeks out news sources that are aligned with his position. When he comes across news stories about shootings, he interprets them in a way that supports his current point of view.

These two people have very different opinions on the same subject and their interpretations are based on their beliefs. Even if they read the same story, their bias tends to shape the way they perceive the details, further confirming their beliefs.

Impact of Confirmation Bias

In the 1960s, cognitive psychologist Peter Cathcart Wason conducted a number of experiments known as Wason's rule discovery task. He demonstrated that people have a tendency to seek information that confirms their existing beliefs. Unfortunately, this type of bias can prevent us from looking at situations objectively. It can also influence the decisions we make and lead to poor or faulty choices.

During an election season, for example, people tend to seek positive information that paints their favored candidates in a good light. They will also look for information that casts the opposing candidate in a negative light.

By not seeking out objective facts, interpreting information in a way that only supports their existing beliefs, and only remembering details that uphold these beliefs, they often miss important information. These details and facts might have otherwise influenced their decision on which candidate to support.

Expert Observations

In his book Research in Psychology: Methods and Design, C. James Goodwin gives an example of confirmation bias as it applies to extrasensory perception.

"Persons believing in extrasensory perception (ESP) will keep close track of instances when they were 'thinking about Mom, and then the phone rang and it was her!' Yet they ignore the far more numerous times when (a) they were thinking about Mom and she didn't call and (b) they weren't thinking about Mom and she did call.

"They also fail to recognize that if they talk to Mom about every two weeks, their frequency of 'thinking about Mom' will increase near the end of the two-week-interval, thereby increasing the frequency of a 'hit.'"

As Catherine A. Sanderson points out in her book Social Psychology, confirmation bias also helps form and re-confirm stereotypes we have about people: "We also ignore information that disputes our expectations. We are more likely to remember (and repeat) stereotype-consistent information and to forget or ignore stereotype-inconsistent information, which is one way stereotypes are maintained even in the face of disconfirming evidence.

"If you learn that your new Canadian friend hates hockey and loves sailing, and that your new Mexican friend hates spicy foods and loves rap music, you are less likely to remember this new stereotype-inconsistent information."

Confirmation bias is not only found in our personal beliefs, it can affect our professional endeavors as well. In the book Psychology, Peter O. Gray offers this example of how confirmation bias may affect a doctor's diagnosis.

"Groopman (2007) points out that the confirmation bias can couple with the availability bias in producing misdiagnosis in a doctor's office. A doctor who has jumped to a particular hypothesis as to what disease a patient has may then ask questions and look for evidence that tends to confirm that diagnosis while overlooking evidence that would tend to disconfirm it.

"Groopman suggests that medical training should include a course in inductive reasoning that would make new doctors aware of such biases. Awareness, he thinks, would lead to fewer diagnostic errors. A good diagnostician will test his or her initial hypothesis by searching for evidence against that hypothesis."

A Word From Verywell

Unfortunately, we all have confirmation bias. Even if you believe you are very open-minded and only observe the facts before coming to conclusions, it's very likely that some bias will shape your opinion in the end. It's very difficult to combat this natural tendency.

That said, if we know about confirmation bias and accept the fact that it does exist, we can make an effort to recognize it by working to be curious about opposing views and really listening to what others have to say and why. This can help us better see issues and beliefs from another perspective, though we still need to be very conscious of wading past our confirmation bias.

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4 Sources
Verywell Mind uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. American Psychological Association. Confirmation bias. APA Dictionary of Psychology.

  2. Goodwin CJ, Goodwin KA. Research in Psychology: Methods and Design. 7th ed. John Wiley and Sons; 2013.

  3. Sanderson CA. Social Psychology. 1st edi. John Wiley and Sons; 2010.

  4. Gray PO. Psychology. 6th ed. Worth Publishers; 2011.

Additional Reading
  • Poletiek FH. Hypothesis-Testing Behavior. Psychology Press, 2013.