What Is a Cognitive Bias?

An image of two brains on a scale to represent cognitive biases.
(Last Updated On: September 2, 2021)

Cognitive bias is an unconscious systematic pattern of thinking that can often result in errors in judgment. These biases stem from the brain’s limited resources and need to simplify the world in order to make faster decisions.

Such biases are often the result of limitations or problems in memory, attention, and information-processing. While such biases often serve as shortcuts that help us make sense of the world around us, they also introduce errors in problem-solving and decision-making.

Cognitive biases were first described by Amos Tversky and Daniel Kahneman in 1972 and grew out of their work in heuristics. Heuristics are mental shortcuts that help speed up thinking. While these biases often help people make sense of the world, but they also introduce distortions, illogical thinking, irrationality, and poor judgments.

In this article, learn more about some of the most common types of cognitive biases. Also, discover how to look and change bias in your own thinking.


Researchers have identified more than 175 different cognitive biases. Some of the most common ones include:

Confirmation Bias

This common type of bias involves paying more attention to information that reinforces the things that you already believe. At the same time, you might discount or ignore things that offer contrary evidence.

Hindsight Bias

This bias, also known as the ‘I-knew-it-all-along’ effect, involves people overestimating the predictability of events. In hindsight, the outcome appears obvious and inevitable. This often leads people to feel overly confident in their own predictions about the future.

Anchoring Bias

This type of bias involves relying too heavily on the first piece of information. Once you hear something, you then rely on it as a baseline to compare further information. If you see a car at a certain price, for example, you might then use that anchor to compare all future car prices.

Self-Serving Bias

The self-serving bias involves a tendency to take personal credit for success but blame external forces for failures. While this can protect self-esteem, it can prevent people from accurately evaluating the causes behind the events in their lives.

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Bandwagon Effect

This type of cognitive bias causes people to be more likely to go along with something if many other people are also doing the same thing.

Fundamental Attribution Error

When it comes to attributing the action of others, people often tend to place too much emphasis on personal characteristics of the individual while downplaying or underestimating external or situational factors.

Halo Effect

This effect involves judging all of a person’s qualities based on one trait. Also known as the ‘what is beautiful is good’ effect, an example would be believing someone is competent, kind, and generous because they are physically attractive.

Dunning-Kruger Effect

This effect occurs when people mistakenly think that they know a great deal about a topic because of their limited knowledge of the subject. The less they understand about it, the easier the topic appears. It is only after becoming more informed that people begin to appreciate the complexity and depth of the subject and are able to put their own limited understanding in context.

Ingroup Bias

The ingroup bias involves attributing positive traits to people who share group affiliations with you. This might involve believing people in that group are more qualified or competent, but also favoring members of that group while discounting members of outside groups.

Availability Bias

This type of cognitive bias causes people to base decision on information that is immediately available. Rather than look for outside information, people base their decisions on the first examples that come to mind.

Projection Bias

The projection bias involves overestimating how much other people agree with the way that you think, feel, or believe. It shares similarities with the false consensus effect.

Researchers refer to the inability to recognize your own cognitive biases as the bias blind spot.

Identifying Bias

Cognitive biases are natural and happen to everyone. While cognitive biases are often viewed as problematic, they can also be adaptive. 

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They do often lead to fairly accurate and fast decisions while reducing the amount of mental effort required to make a choice. This can be particularly important in situations where a person is facing a threat and needs to come up with a solution quickly.

Learning how to spot them can help you better determine if they are serving a purpose or preventing you from making accurate judgments.

If you suspect that your thinking is being hindered by bias, ask yourself some questions:

  • Are you only paying attention to information that confirms what you already believe?
  • Are you blaming the misfortunes of others to their own personal failings while attributing your own misfortunes to external forces?
  • Do you assume that most people agree with your beliefs and opinions on different topics?
  • Do you assume that the first thing you learn about something is accurate and discount subsequent information?
  • Is your initial good impression of something affecting your subsequent assessments?
  • Do you ever look back on an event and feel like you knew the outcome all along?

Detecting and preventing bias every type of bias isn’t possible. Everyone has biases, often shaped by their perceptions and experiences.

While you might not be able to prevent it, you can get better at identifying your own biases and looking for ways to be less biased and more objective when possible.

Preventing Bias

What can you do to help minimize the potentially negative effects of cognitive biases on your judgments? Steps that you can take include:

  • Take your time: When you are making a decision, try to give yourself some time to consider all of the aspects of the situation and the potential pros and cons of each choice.
  • Reduce distractions: When other things are competing for your attention, it reduces the available mental resources you have for making a decision. Whenever possible, get rid of distractions so that you can really focus on the task at hand.
  • Learn more about bias: Research suggests that cognitive training can be helpful for minimizing biased thinking. Learning to recognize bias in your own thinking is often the first step to overcoming it. A 2019 study published in the journal Psychological Science found that participants who had been trained about the effects of bias were 19% less likely to be influenced by the confirmation bias when making a choice.
  • Challenge your thinking: Actively questioning your choices and looking for sources of bias can also be helpful. Analyzing your choices can help you think more critically in a wide variety of situations.
  • Get some perspective: If you’re having trouble checking yourself for bias, consider seeing what other people think. Group decisions aren’t necessarily free from bias (because other people are affected by cognitive biases as well), but sometimes getting an outside perspective can help you see things from another point of view. 
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Cognitive biases are flaws in the way that we think. They can speed up thinking and simplify the world around us, but they can also cause us to make poor choices.

Getting rid of all bias isn’t realistic, but there are ways to get better at spotting biases in your thinking. Learn more about these biases, how they work, and the effects that they have can help you get better at spotting flaws in thinking and make better decisions.


American Psychological Association. Availability heuristic. APA Dictionary of Psychology; 2020.

Friedman HH. Cognitive biases that interfere with critical thinking and scientific reasoning: a course module. SSRN Journal. Published online 2017. doi:10.2139/ssrn.2958800

Sellier A-L, Scopelliti I, Morewedge CK. Debiasing training improves decision making in the field. Psychol Sci. 2019;30(9):1371-1379. doi:10.1177/0956797619861429

van Geene K, de Groot E, Erkelens C, Zwart D. Raising awareness of cognitive biases during diagnostic reasoning. Perspect Med Educ. 2016;5(3):182-185. doi:10.1007/s40037-016-0274-4

Yik M, Wong KFE, Zeng KJ. Anchoring-and-adjustment during affect inferences. Front Psychol. 2019;9:2567. doi:10.3389/fpsyg.2018.02567