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How Confirmation Bias Affects Decision-Making

Humans have certain cognitive tendencies that affect their decision-making. Confirmation bias is one of them. It is a tendency to look for information that is in line with our previous expectations and to disregard or destroy any information that is contradictory to our original belief.

Early Experiment On Confirmation Bias

By: Peter Wason (1960)

Aim: The experiment was conducted to demonstrate confirmation bias.


  • He gave a three number sequence (2-4-6) to British university students and asked them to guess the rule he must have used to develop the series.
  • The rule was simple, it was three ascending numbers.
  • Before submitting their answers, students had to create their own 3-number sets and Wason asked them if their sets conformed to his rule.
  • They were told that when they are sure of the answer, they can announce it.


  • The students announced it confidently, without any doubt even though most of them had a wrong idea about the set.
  • They thought it was counting by twos and so they looked for confirming evidence by testing 6-8-10 or 100-102-104 and so on.
  • This was one of the first real-life demonstrations of confirmation bias.

Confirmation Bias In Daily Life

Daniel likes the popular TV show ‘Friends.’ He watches the show regularly and stays updated on any positive news about the show that confirms his original belief about the show. When he receives any negative news or feedback about the show, he argues with that information and sees the new information in a positive light because of his own bias.

Simran despises the TV show, ‘Friends.’ She believes that the humour in the show is outdated and problematic. She reads blogs and articles that mention the problematic jokes made on the show. When she listens to any positive views on the show, she argues with those views and mentions how those jokes are regressive. She is unable to perceive the show positively because of her own bias.

Daniel and Simran have opposing views about the same show, and they continue to focus on their own beliefs even in the light of new information. That shows their confirmation bias. This happens to a lot of people in day-to-day situations.

Why Does Confirmation Bias Occur?

1. To Process Information

As humans, we must process a huge amount of information regularly and confirmation bias seems to be an easier way to process information. It would take a lot of effort and time if we assessed each piece of information.

Sometimes, it is not even possible to have access to so much information. Thus, a lot of us end up looking for information that we already like or prefer to make decisions and form views.

2. Self-Esteem

People use confirmation bias for protecting their self-esteem. They form a belief or an opinion on something and are inclined towards information that supports these beliefs so that they can feel they are correct. The information that supports their beliefs makes them feel confident and strengthens their original belief.

3. For Lessening Cognitive Dissonance

Another reason for confirmation bias is cognitive dissonance. Cognitive dissonance is the tendency to feel conflicted because of two opposing beliefs held by the same individual. People do not like feeling uncomfortable, hence, they try to lessen their dissonance. They do that by choosing one belief and looking for information that supports only the chosen belief.

How Does Confirmation Bias Affect Us?

1. Creates And Encourages Stereotypes:

Confirmation bias can establish and strengthen stereotypes. When we have a stereotype about someone, we look for information that is consistent with our beliefs and we disregard any contradicting evidence, thus strengthening that stereotype. This is one of the reasons why stereotypes continue to consume us currently too.

For example, Siya believes that women cannot be good at maths, which is unfortunately a popular stereotype. This stereotype is strengthened in her mind when she reads research literature that supports her belief and opposes any information that contradicts her views.

2. Affects Political Decision-Making:

People have certain preferred candidates when it comes to politics. Confirmation bias can make them inclined towards only looking for positive information about the preferred candidate and ignoring any contradicting evidence.

This could be risky if people believe and look at only the good side of the preferred candidate and grow overconfident in that belief, thereby, affecting their voting decision, which could ultimately affect most citizens.

3. Affects Job Prospects For Certain Candidates:

Confirmation bias can affect recruitment and selection processes at workplaces.

For example, Kim, an employer, believes that pregnant women should not be given a promotion, and looks for information that supports his belief. This belief impacts the pregnant women at his office who are good candidates for a promotion.

Confirmation bias could also lead to a less diverse work environment if employers have certain beliefs about certain social groups. These social groups can be disadvantaged because of this selective recruitment process.

For example, Reet is a recruiter at a big company. He mostly hires white males because he believes that white males are more competent than other racial groups. This invalid belief makes the company less diverse and creates a barrier for other groups to enter the company.

Research Evidence for Confirmation Bias

Study 1:

By: David M. Marsh, Teresa J. Hanlon (2007)

Aim: To determine whether behavioral observations were influenced by previous expectations of the observers.


  • Two experiments were conducted in which participants observed aggression and foraging behaviours of red-backed salamanders (type of animal).
  • There were 2 groups of participants. In both the experiments, one group was given specific information about sex differences in these animals and the other group was given the opposite information about the sex differences in these animals.
  • In the first experiment, the participants observed live salamanders and in the second experiment, participants observed identical videotapes of salamanders.


  • The expectations of the participants tended to bias their observations of the animals, but only to a small to moderate degree.
  • No gender differences were found.

Study 2:

By: Temerlin (1968)

Aim: To study the relationship between confirmation bias and the accuracy of clinical diagnoses.


  • Mental health practitioners were asked to assess a case interview with a client. Specifically, they were asked to evaluate the evidence in the case and make a professional decision regarding the nature and severity of the client’s problem.
  • Through random assignment, half of the clinicians were initially told that the patient might be psychotic. This information was not given to the other professionals.
  • The client being interviewed was in decent emotional health. however, this information was not given to both groups.


  • The practitioners’ judgements in the two groups were completely different.
  • Practitioners who were told that the patient might be psychotic were closer to finding data to confirm the patient was mentally ill and in need of therapy than were practitioners who were not told about the psychosis.
  • Thus, even though all the professionals were presented with the same client data, they came to evaluate this information differently, which depicts confirmation bias.

Confirmation Bias and COVID-Vaccination Hesitancy

Packer believed that the COVID vaccine goes against his religious beliefs. He believed that immunizations are useless. He refused to get vaccinated and is hesitant when people pressurise him to get it. There has been tremendous research on the benefits of the vaccine but Packer dismisses that information and reads articles about how the vaccine is useless and against religious sentiments.

This is a clear instance of confirmation bias. Packer only chooses to believe the information that is consistent with his belief and ignores information that is not in line with his belief. This could lead to risky consequences.

How To Reduce Confirmation Bias?

  • Learn to question your beliefs and sources. Expand your knowledge by using multiple sources to gain information. Use appropriate sources and read complete articles to be sure of the information. Do not scroll over headlines, if you want to form a solid belief or opinion.
  • Evaluate the sources and look for evidence or research, not just the opinions of an author.
  • Take alternative beliefs into account while reading information. Confirmation bias includes focusing on only one side of the story, so taking another side also into account could help in reducing bias.
  • Surround yourself with a diverse range of people, so that you can listen to multiple opinions. Be open to views that don’t match yours.
  • Be aware and curious. Politicians and religious entities tend to repeat the same facts about themselves several times. This is a brainwashing tactic that makes use of familiarity. When you have heard something too many times, you are likely to believe it’s true. Hence, stay aware and question repetitions.
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