What Is Cognitive Bias? Definition and Examples

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A cognitive bias is a systematic error in thinking that impacts one's choices and judgments. The concept of cognitive bias was first proposed by Amos Tversky and Daniel Kahneman in a 1974 article in Science. Since then, researchers have identified and studied numerous types of cognitive biases. These biases influence our perception of the world and can lead us to poor decision-making.

Key Takeaways: Cognitive Bias

  • Cognitive biases increase our mental efficiency by enabling us to make quick decisions without any conscious deliberation.
  • However, cognitive biases can also distort our thinking, leading to poor decision-making and false judgments.
  • Three common cognitive biases are fundamental attribution error, hindsight bias, and confirmation bias.

Causes of Cognitive Bias

As humans, we generally believe ourselves to be rational and aware. However, our minds often respond to the world automatically and without our awareness. When the situation demands it, we are able to put mental effort into making decisions, but much of our thinking takes place outside of conscious control.

In his book Thinking Fast and Slow, Nobel Prize winning psychologist Daniel Kahneman refers to these two types of thinking as System 1 and System 2. System 1 is fast and intuitive, relying on mental shortcuts in thinking—called heuristics—to navigate the world more efficiently. By contrast, System 2 is slow, introducing deliberation and logic into our thinking. Both systems impact how we make judgments, but System 1 is in charge a majority of the time.

We unconsciously "prefer" System 1 because it is applied effortlessly. System 1 includes preferences we are born with, like our desire to avoid losses and run from snakes, and associations we learn, like the answers to simple math equations (quick: what’s 2+2?) and the ability to read.

Meanwhile, System 2 requires attention in order to work, and attention is a limited resource. Thus, the deliberate, slow thinking of System 2 is only deployed when we're paying attention to a specific problem. If our attention is drawn to something else, System 2 is disrupted. 

Are Cognitive Biases Rational or Irrational?

It may seem irrational that we rely so heavily on System 1 in our thinking, but as it turns out, the preference has a logical explanation. If we had to carefully examine our options every time we made a decision, we would quickly become overwhelmed. Need an example? Imagine the mental overload of deliberately weighing the pros and cons of each potential route to work every single day. Using mental shortcuts to make these decisions enables us to act quickly. Sacrificing logic for speed helps us cut through the complexities and the wealth of information inundating us on a daily basis, making life more efficient.

For example, let's say you're walking home alone at night and suddenly hear a strange sound behind you. A cognitive bias may cause you to believe the noise is a sign of danger. As a result, you’ll quicken your pace so that you can get home as soon as possible. Of course, the noise may not have come from someone who means to harm you. It may have been a stray cat rummaging in a nearby trash can. However, by using a mental shortcut to quickly come to a conclusion, you may have stayed out of danger. In this way, our reliance on cognitive biases to navigate through life can be adaptive.

On the other hand, our cognitive biases can get us into trouble. They sometimes result in distorted thinking that negatively impacts the choices and judgments we make. Cognitive biases also lead to stereotyping, which can become ingrained from our exposure to our culture’s biases and prejudices towards different races, religions, socioeconomic statuses, and other groups. Personal motivations, social influence, emotions, and differences in our information processing capacities can all cause cognitive biases and influence how they manifest themselves.

Examples of Cognitive Biases

Cognitive biases impact us in many areas of life, including social situations, memory recall, what we believe, and our behavior. They have been used in disciplines like economics and marketing to explain why people do what they do as well as to predict and influence people’s behavior. Take the following three cognitive biases as examples.

Fundamental Attribution Error

The fundamental attribution error, also known as the correspondence bias, is the general tendency to attribute another individual’s behavior to their personality and internal traits rather than the situation or external factors. It is considered a bias of social judgment. For example, a series of studies showed that people attribute the actions of a TV character to the personality traits of the actor playing the character. This happened despite the fact that the participants were aware that the behavior of the actors was dictated by a script. Numerous studies have demonstrated this tendency to believe that whatever behavior an individual exhibits arises from their individual characteristics, even when knowledge of the situation should indicate otherwise.

Hindsight Bias

Hindsight bias, or the “I-knew-it-all-along” effect, leads us to believe that we could have correctly predicted the outcome of past events after we've learned what the outcome was. It is a bias of memory in which people incorrectly believe they knew the outcome of an event all along even though they didn't. They believe they remember correctly predicting the outcome, so they also believe that their memories are consistent over time. This bias makes it difficult to properly evaluate a decision, as people will focus on the outcome and not the logic of the decision-making process itself. For example, if an individual’s favorite team wins a big game, they may claim they knew the team would win, even if they were uncertain before the game.

Confirmation Bias

Confirmation bias is a bias of belief in which people tend to seek out, interpret, and recall information in a way that confirms their preconceived notions and ideas. In other words, people attempt to preserve their existing beliefs by paying attention to information that confirms those beliefs and discounting information that could challenge them. Confirmation bias can be seen in action in many facets of life, including what political policies one champions and whether one believes in a specific scientific explanation for phenomena like climate change or vaccines. Confirmation bias is one reason it’s so challenging to have a logical discussion about polarizing hot-button issues.


  • Aronson, Elliot. The Social Animal. 10th ed., Worth Publishers, 2008.
  • Cherry, Kendra. “Confirmation Bias.” VeryWell Mind, 15 October 2018. https://www.verywellmind.com/what-is-a-confirmation-bias-2795024
  • Cherry, Kendra. “How Cognitive Biases Influence How You Think and Act.” VeryWell Mind, 8 October 2018.https://www.verywellmind.com/what-is-a-cognitive-bias-2794963
  • Kahneman, Daniel. Thinking Fast and Slow. Farrar, Straus and Giroux, 2011.
  • Tal-Or, Nurit, and Yael Papirman. “The Fundamental Attribution Error in Attributing Fictional Figures’ Characteristics to the Actors.” Media Psychology, vol. 9, no. 2, 2007, p. 331-345. https://doi.org/10.1080/15213260701286049
  • Tversky, Almos, and Daniel Kahneman, “Judgment Under Uncertainty: Heuristics and Biases.” Science, vol. 185, no. 4157, 1974, pp. 1124-1131. doi: 10.1126/science.185.4157.1124