Confirmation Bias

Dr Thanh-Tam Pham - 20/11/2020


Confirmation bias is a type of Cognitive bias that involves the tendency to search for information that confirms one’s prior existing beliefs or values. It differs from Belief perseverance as the latter does not need to gather information.

People tend to unconsciously select information that support their views but ignore other non supportive information.

For an example, during an election time, people tend to seek positive information about their favoured candidate and look for negative information about the opposing candidate. People do not seek out all the objective facts and tend to interpret information in a way to support their existing beliefs. It can lead to poor choice of candidate. We can see that in the US 2020 president election, many people believe in election fraud without any evidence and did not see that those beliefs create weakness and division in their country that they believe to be “great”.

When people would like a certain idea to be true they end up believing it to be true by gathering more information to confirm their views and reject information that casts doubt on their belief.

Confirmation bias contributes to overconfidence in people’s personal beliefs and even strengthens those beliefs in the face of contrary evidence. These biases will lead to poor decisions in politics, in financial organizations and even in scientific researches.  Even scientists and intelligent people can be prone to confirmation bias.

It is a result of unintentional information processing rather than deliberate deception. Therefore, it cannot be completely eliminated but it can be reduced with awareness of its existence and training in thinking skills and developing good strategies.


Why there is Confirmation bias:

1-   Information processing:

In real life, there is limitless information so to form a non biased belief, people have to critically evaluate every piece of information available and this is often unfeasible so they tend to look for information that supports their existing beliefs. It is a more efficient way for the mind to process information by putting more weight to evidence that confirms their beliefs and undervaluing evidence that could disprove them.  People displays this bias in collecting information but there could be biased interpretation as well. Even when two persons have the same information like listening to the same lecture or speech, the way they interpret it can be different and biased. People often hear what they want to hear and take away the information that resonates with their pre-existing beliefs.

People may have biased memory and selectively recall evidence to reinforce their expectations and beliefs. Any information that matches their prior thinking will be more easily stored and recalled or any information that are striking or surprising are more memorable.


2-   Protect the ego and self esteem:

People unconsciously would like to prove that their beliefs are accurate. It is painful for the ego to accept that their original beliefs are turned out to be wrong. To make themselves to feel confident, they automatically look for information that supports their existing beliefs.

In real life, evidence is often complex and mixed. For example if we want to find evidence to support our good impression about the person we love, we can find ample evidence to favour our hypothesis and ignore the negative sides of that person. That is why a lot of relationships break down after the two persons live together and they start to face with the negative sides of each other. Sometimes a person can see the negative side of his partner but wishfully thinks that he can change his partner’s beliefs once they get married. But unfortunately it is simply a form of self deception as it is nearly impossible to change anyone’s beliefs or characters due to confirmation bias.

Mental conflict occurs when a person holds 2 contradictory beliefs that cause psychological stress. Confirmation bias serves this purpose by avoiding contradictory evidence and seeking confirming information. People experience negative emotions such as disappointment, sadness when exposed to evidence that contradict their own beliefs.


Implications of Confirmation bias:

1-   Politics:

Confirmation bias can influence voting decision as people tend to look for information confirming to their beliefs in the candidates and ignoring other views.

2-   Employee recruitment:

Confirmation bias can introduce unconscious discrimination in interviews to recruit employees. It can affect employment diversity because of preconceived ideas about different social groups.

3-   Scientific research:

Bias can happen when people phrase questions to receive affirmative answers to support their theory. Open ended questions will give people the opportunity to express their true ideas and avoid bias in collecting information.

4-   Psychological problems:

People who are anxious may constantly monitor signs of danger as they can view the world as dangerous. Hypochondriacs try to focus on minor symptoms and gather more information about serious illnesses to explain their symptoms as they have an intense fear of having an undiagnosed serious medical problem.


How to avoid confirmation bias:

Confirmation bias is unintentional and people may not be aware of it. Therefore, it is important that we are aware of its existence and develop strategies to avoid it. We must seek out information from a variety of sources and consider our belief from multiple perspectives. We have to be open- minded and try to challenge what we think and try to look for evidence to prove that we are wrong. We need to have self confidence to be able to gather all the information without the need to please our ego.

In drug research, to avoid confirmation bias, people set up double blind studies and comparison of the effect of the drug to placebo.


In summary, people are prone to believe what they want to believe, and seeking to confirm their beliefs come naturally and automatically.. This explains why contradictory opinions can survive and spread in the community. For examples, there are people who believe in legalisation of Marijuana and those who are against, those who believe in climate changes versus climate change skeptics or people who do not believe in vaccinations…Establishing the truth can be very difficult and people may not believe the truth even in the face of overwhelming evidence.