78 Cognitive Bias Examples

cognitive bias examples definition

Examples of cognitive bias include optimism bias (overpredicting the likelihood of the best outcome) and egocentric bias (being biased towards outcomes that benefit ourselves).

The fact is, most of us overestimate our thinking skills. We think we are objective in our analysis and a good judge of the accuracy and credibility of information.

Unfortunately, that is not actually the case. Most people are full of biases in their judgments and often make inaccurate conclusions.

This is called a cognitive bias. It is a bias in our thinking that is systematic, meaning we regularly make this bias as if it’s a logical and objective conclusion, even though it isn’t.

There are many reasons for our faulty analyses. Sometimes it is a defense mechanism that protects our self-esteem. At other times it just because it takes a lot of cognitive effort to be accurate. It’s just easier to think less.

Cognitive Bias Examples

See Also: The Types of Bias

Definition of Cognitive Bias

Because people like to conserve energy and thinking requires a lot of effort, we take a lot of short-cuts. These short-cuts in our thinking our called cognitive bias. A cognitive bias is defined as an unconscious error in thinking.

It is completely unintentional and automatic. The reason people have cognitive biases is because there simply isn’t enough time to go through a lengthy analysis of every situation we encounter, especially in modern times when life is so busy.

We are literally bombarded with vast amounts of information on a daily, even on a minute-by-minute basis. If we tried to undergo a thorough and objective analysis of all the input we encountered, it would be maddening. Therefore, we need cognitive biases.

Explanation of Common Cognitive Biases

1. Confirmation Bias

This bias may be the most prevalent bias of all. It is our tendency to seek out information that confirms our beliefs.

For example, only watching news channels that are consistent with your political ideology. When this happens, we are only going to hear news that confirms our views.

Another example is when we only follow certain people on social media that we agree with on various social issues. That means that each day we will see posts that are consistent with our perspective.

The unfortunate result of having a strong confirmation bias is that we are unlikely to even consider opposing views. This can give us a very narrow view of the world. Although it might boost our self-esteem to think that others agree with us, it also prevents us from growing as an individual.

Read about confirmation bias examples in our full write-up on this topic.

2. The Halo Effect

When we have a positive impression of someone because they are good in one area, we have a tendency to think that they are good at other areas as well.

It also applies to our thinking about their personality traits or work performance.

For example, if a manager really likes the enthusiasm of a certain employee, they may be slightly blinded by that impression and give them a very favorable performance review. That person might not actually be a very high-performing member of the team, but the halo effect means they are evaluated favorably in other work domains.

The halo effect has many applications, including in marketing and consumer behavior, classroom performance, and various types of competitions that involve judges.

3. Optimism Bias

This bias is very straightforward: It is our tendency to think that bad things are unlikely to happen to us.

Even though we may see other people suffer negative consequences all around us, this bias prevents us from concluding that we will also suffer that fate.

Some examples include: believing that we will live to a very old age, even though many of our ancestors died young, or that we will be successful trading in the stock market even though most people fail miserably.

While a lot of biases are relatively harmless, there are many scenarios in which having the optimism bias can lead to disastrous consequences.

4. Fundamental Attribution Error

We tend to attribute the actions of others to their personality. So, when we see someone get into a car accident, we might be likely to conclude that they are a bad driver.

When we see people in an unemployment line, our first thought might be that they are lazy or lack motivation.

Psychologists have identified several reasons for this bias. One is that when we are observing another person’s behavior, we are really not privy to a lot of information about the situation. For example, the person in the car crash may have been cut-off in traffic before we got there.

Also, it takes time and effort to think about another person’s situation, and one thing we know is that people can be very lazy thinkers. It is just easier to make a sweeping statement about another person rather than exerting a lot of cognitive effort trying to analyze all of the possible factors involved.

5. Conformity Bias

People are social animals. In many ways that is a very beneficial trait. Sometimes however, it can lead to shocking behavior. The conformity bias is the tendency for people to go along with the group.

Instead of using our personal judgement and our internal moral standards, the presence of so many other people overwhelms our judgement. One example involves the peer pressure that young adults might feel to drink or engage in risky behavior. Another example is when we witness someone being mistreated by others, we may start to participate as well.

Going against the grain takes courage, can involve some very strong negative consequences, and requires that we resist the pressure to conform. These are all difficult obstacles to overcome.

6. Self-serving Bias

This bias really benefits our self-esteem. It is the tendency to attribute success to internal factors and failures to external ones.

So, if we have done well on a project at work, we will attribute that success to our talent and hard work. However, if the project fails miserably, we are likely to identify external factors as the cause.

The self-serving bias is exactly what it says; it is self-serving. By giving ourselves credit for success and avoiding blame for failure, we are protecting our self-esteem. It is a kind of defense mechanism.

Of course, it has a downside. If we deny responsibility for a failure, it may prevent us from learning from our mistakes and improving. It also might make us look bad in the eyes of others because we refuse to admit our faults.

7. False Consensus Effect

Most people have a very strong belief that other people share their opinions. We often think that others agree with us, even though we have not conducted any surveys on the issue. This is known as the false-consensus effect.

It can be seen in a wide range of scenarios. For example, when discussing controversial issues, people are more like to say that “most people” agree with them. This can make us a bit closed-off to listening to divergent opinions because we discount them as uncommon.

One reason people believe in a false-consensus is because we tend to socialize with people that share of views. So, it makes sense that over time we would form the impression that most people agree with us.

8. The Availability Heuristic

Making accurate, well-thought-out decisions can be difficult. Especially when issues are complicated and the stakes are high. There can be a lot of pressure as well.

Social scientists have put a lot of effort into researching how people make decisions. One key finding is that it is easy for people to rely on information that is the most available in their mind. This means that attention-grabbing information is easier to recall. Unfortunately, that doesn’t mean that the information is very useful. It might not even be accurate.

Training people to make accurate decisions is vital in many professions, such as in medicine, investments and business, and foreign policy.  

9. The Contrast Effect

The contrast effect distorts our perception of something as a result of it being compared to a previous example that is either exceptionally good or poor.

The differences between the two examples are perceived as being more extreme than they actually are.

For example, an HR manager may have a stack of resumes to consider for a new position. If the first one is of a highly qualified candidate with a stellar background, then the resume that follows is likely to be judged less favorably.

The contrast effect is also often used as a sales technique. By presenting a customer with an extremely poor version of a product, then the next one presented will seem so much better. In comparison, the second one just looks superior.

10. The Actor-Observer Bias

The actor-observe bias has to with how we perceive the actions of others and ourselves. Generally speaking, we attribute our behavior to external factors, but the actions of others to internal ones.

For example, if we suffer a period of unemployment, we might be able to generate a lot of reasons for this. Most of those reasons will be about factors outside of our control, such as a bad economy or lots of only a few openings.

However, we might not be so generous when the situation is about someone else. We might think that they are unemployed because they are lazy or lack the necessary skills to land a job.

This bias can lead to a lot of misunderstandings and arguments between individuals, but it is quite difficult to overcome. Having empathy and being able to see things from the other person’s perspective helps.

11. Hindsight Bias

Hindsight bias is a bias that occurs when you look at something that has already happened and say “that was obvious!”

It often makes us more judgmental because we can smugly say we would have done better in the situation. We say “wow, that person was silly that they did that – didn’t they predict the future!” Usually, those people in the situation couldn’t predict the future and, likely, did the best they could.

A hindsight bias example is the Monday morning quarterback. This is a person who, the day after a sports game, passes judgment about how poorly the football players played. Similarly, it might be someone who looks back at a stock market pick and says “That was a terrible decision! Didn’t you predict that the economy was going to crash!”


Cognitive biases are large in number. As it turns out, people are not nearly as good at critical thinking and objective analysis as they think they are. Nearly every day of our lives is full of biases and faulty judgments.

We can see these biases at play when we are observing other people’s behavior and overstating their responsibility. While at the same time, we are perfectly capable of examining the causes of our own actions fairly and without judgment.

Some biases protect our self-esteem and serve as a kind of defense mechanism. When we fail it’s because of external factors that we could not control, but when we win its because of our immense talent and hard-working nature.  

Good or bad, cognitive biases are here to stay for as long as humans are humans, or until AI chips are implanted in our cortex.


Dardenne, B., & Leyens, J. (1995). Confirmation bias as a social skill. Personality and Social Psychology Bulletin, 21(11), 1229–1239

Nisbett, R.E., & Wilson, T.D. (1977). The halo effect: Evidence for unconscious alteration of judgments. Journal of Personality and Social Psychology, 35, 250-256.

Tversky, A., & Kahneman, D. (1973). Availability: A type of heuristic for judging frequency and probability. Cognitive Psychology, 5(2), 207-232. Weiner, B. (1985). An attributional theory of achievement motivation and emotion. Psychological Review, 92(4): 548–573.

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Dr. Cornell has worked in education for more than 20 years. His work has involved designing teacher certification for Trinity College in London and in-service training for state governments in the United States. He has trained kindergarten teachers in 8 countries and helped businessmen and women open baby centers and kindergartens in 3 countries.

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This article was peer-reviewed and edited by Chris Drew (PhD). The review process on Helpful Professor involves having a PhD level expert fact check, edit, and contribute to articles. Reviewers ensure all content reflects expert academic consensus and is backed up with reference to academic studies. Dr. Drew has published over 20 academic articles in scholarly journals. He is the former editor of the Journal of Learning Development in Higher Education and holds a PhD in Education from ACU.

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