Published on 19 September 2022 by Kassiani Nikolopoulou. Revised on 10 March 2023.
Confirmation bias is the tendency to seek out and prefer information that supports our preexisting beliefs. As a result, we tend to ignore any information that contradicts those beliefs. Confirmation bias is often unintentional but can still lead to poor decision-making in (psychology) research and in legal or real-life contexts.
This type of research bias is more likely to occur while processing information related to emotionally charged topics, values, or deeply held beliefs.
Table of contents
- What is confirmation bias?
- Types of confirmation bias
- Confirmation bias examples
- How to avoid confirmation bias
- Other types of research bias
- Frequently asked questions about confirmation bias
What is confirmation bias?
Confirmation bias is a type of cognitive bias, or an error in thinking. Processing all the facts available to us costs us time and energy, so our brains tend to pick the information that agrees most with our preexisting opinions and knowledge. This leads to faster decision-making. Mental ‘shortcuts’ like this are called heuristics.
When confronted with new information that confirms what we already believe, we are more likely to:
- Accept it as true and accurate
- Overlook any flaws or inconsistencies
- Incorporate it into our belief system
- Recall it later, using it to support our belief during a discussion
On the other hand, if the new information contradicts what we already believe, we respond differently. We are more likely to:
- Become defensive about it
- Focus on criticising any flaw, while that same flaw would be ignored if the information confirmed our beliefs
- Forget this information quickly, not recalling reading or hearing about it later on
Types of confirmation bias
There are three main ways that people display confirmation bias:
- Selective search
- Selective interpretation
- Selective recall
Biased search for information
This type of bias occurs when only positive evidence is sought, or evidence that supports your expectations or hypotheses. Evidence that could prove them wrong is systematically disregarded.
If you reverse the question and type ‘are cats better than dogs?’, you will get results in support of cats.
This will happen with any two variables: the search engine ‘assumes’ that you think variable A is better than variable B, and shows you the results that agree with your opinion first.
Instead, try typing the question ‘which one is better, A or B?’ This is more likely to yield a balanced mix of results.
Biased interpretation of information
Confirmation bias is not limited to the type of information we search for. Even if two people are presented with the same information, it is possible that they will interpret it differently.
The reader who doubts climate change may interpret the article as evidence that climate change is natural and has happened at other points in history. Any arguments raised in the article about the negative impact of fossil fuels will be dismissed.
On the other hand, the reader who is concerned about climate change will view the information as evidence that climate change is a threat and that something must be done about it. Appeals to cut down fossil fuel emissions will be viewed favourably.
The two readers have very different opinions on the same subject, formed prior to reading the article. Their interpretations are based on their preexisting beliefs. Even though they read the same story, their bias shapes how they evaluate the information, further reinforcing their existing beliefs.
Biased recall of information
Confirmation bias also affects what type of information we are able to recall.
A week after encountering the story, the reader who is concerned about climate change is more likely to recall these arguments in a discussion with friends. On the contrary, a climate change doubter likely won’t be able to recall the points made in the article.
Due to confirmation bias, we tend to memorise and recall information that is more in line with our existing ideas.
Confirmation bias examples
Confirmation bias has serious implications for our ability to seek objective facts. It can lead individuals to ‘cherry-pick’ bits of information that reinforce any prejudices or stereotypes.
An overworked physician, believing this is just drug-seeking behaviour, examines him hastily in the hall. The physician confirms that all of the man’s vital signs are fine: consistent with what was expected.
The man is discharged. Because the physician was only looking for what was already expected, she missed the signs that the man was actually having a problem with his kidneys.
Relying on a preliminary hunch in this manner is an example of confirmation bias, and a potential pitfall in medical decision-making.
Confirmation bias can lead to poor decision-making in various contexts, including interpersonal relationships, medical diagnoses, or applications of the law.
Due to this, you unconsciously seek information to support your hypothesis during the data collection phase, rather than remaining open to results that could disprove it. At the end of your research, you conclude that memory games do indeed delay memory loss.
Due to confirmation bias, a systematic error is introduced in your research, making the impact of memory games appear greater than it actually is. This leads to false conclusions.
How to avoid confirmation bias
Although confirmation bias cannot be entirely eliminated, there are steps you can take to avoid it:
- First and foremost, accept that you have biases that impact your decision-making. Even though we like to think that we are objective, it is our nature to use mental shortcuts. This allows us to make judgements quickly and efficiently, but it also makes us disregard information that contradicts our views.
- Do your research thoroughly when searching for information. Actively consider all the evidence available, rather than just the evidence confirming your opinion or belief. Only use credible sources that can pass the CRAAP test.
- Make sure you read entire articles, not just the headline, prior to drawing any conclusions. Analyse the article to see if there is reliable evidence to support the argument being made. When in doubt, do further research to check if the information presented is trustworthy.
Other types of research bias
Cognitive bias
- Confirmation bias
- Baader–Meinhof phenomenon
Selection bias
- Sampling bias
- Ascertainment bias
- Attrition bias
- Self-selection bias
- Survivorship bias
- Nonresponse bias
- Undercoverage bias
Other
- Hawthorne effect
- Observer bias
- Omitted variable bias
- Publication bias
- Pygmalion effect
- Recall bias
- Social desirability bias
- Placebo effect
Frequently asked questions about confirmation bias
- Why is bias in research a problem?
-
Bias in research affects the validity and reliability of your findings, leading to false conclusions and a misinterpretation of the truth. This can have serious implications in areas like medical research where, for example, a new form of treatment may be evaluated.
- What makes a source credible?
-
A credible source should pass the CRAAP testand follow these guidelines:
- The information should be up to date and current.
- The author and publication should be a trusted authority on the subject you are researching.
- The sources the author cited should be easy to find, clear, and unbiased.
- For a web source, the URL and layout should signify that it is trustworthy.
- What are threats to internal validity?
-
There are eight threats to internal validity: history, maturation, instrumentation, testing, selection bias, regression to the mean, social interaction, and attrition.
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Kassiani Nikolopoulou
Kassiani has an academic background in Communication, Bioeconomy and Circular Economy. As a former journalist she enjoys turning complex scientific information into easily accessible articles to help students. She specialises in writing about research methods and research bias.
