Common Cognitive Biases: A Comprehensive List With Examples

Cognitive biases are patterns of thinking that distort or skew information processing, often leading to errors. These biases often occur when we make a quick decision using intuition or heuristics, which are simple rules or shortcuts that we use to make decisions and solve problems quickly without necessarily considering all available information.

While human intuition is extremely useful for many things, and should not simply be ignored, there are also plenty of known situations in which using our intuition or "going with our gut" systematically leads us to inaccurate conclusions and unhelpful behaviors.

In the early 1970s, cognitive psychologists Amos Tversky and Daniel Kahneman introduced the term 'cognitive bias' after studying perceptual bias in problem-solving that used heuristics. Since then, cognitive psychology has demonstrated that cognitive biases occur systematically and universally and are involuntary: no one is totally immune to them.

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How Rational Are You, Really?

List of the most common cognitive biases

Here, we list many of the most common cognitive biases. We strongly recommend reading the second part of this article, where we answer popular questions and clarify common misunderstandings about the topic.

Ambiguity Effect?

The Ambiguity Effect is a cognitive bias whereby people who are faced with a decision tend to pick an option for which they know the probability of a good outcome, rather than an option for which the probability of a good outcome is unknown or ambiguous. This may occur even if the known probability is low and picking it isn't the best strategy.

Example

• "There are ten doors in front of me. I know that if I pick Door 1, I have a 5% chance of winning a decent prize. But if I pick Door 2, I don't know what the odds of winning are or how good the prize would be. I guess I'll pick Door 1!"

• When trying to decide which job to take, a person might choose the known option (e.g., where they have interacted with the people involved before and have done a similar role before) over the ambiguous option (where they don't know the people involved or what the role will really entail) even in cases where the latter is actually a better choice according to the information available.

Anchoring Bias

Anchoring Bias occurs when a person's expectation about one thing is affected by something mostly or entirely irrelevant they saw, heard, or thought before, such as an irrelevant number. In other words, it occurs when a person's beliefs or behaviors are influenced by a specific piece of information far more than they should be given how much evidence that information actually provides.

Examples

• When buying an expensive car from a used car salesman, the initial quote you get might anchor you to a particular price, even if that number was made up by the saleperson and is not at all reflective of the typical price of that car.

• When considering buying an online course, the course might mention that "similar courses can cost upwards of $500 - but this course is availabe for just $250!" That $500 may make the $250 course price seem relatively cheap, even though there may be other companies that offer a similar course for just $50 that were simply not mentioned.

Attention Bias

Attention Bias occurs when some information or evidence holds a disproportionate amount of a person's attention because of that person's environment or history, or because of people's natural instincts.

Example

• You might only focus on what could go wrong in a situation, less often considering what could go right or how things are likely to go. You might worry a lot (rather than on focussing on what could go well), reducing your overall quality of life and preoccupying your mind with unnecessary worries.

• When presented with a grid of faces, some neutral, some happy, and some angry, you may automatically focus on the angry faces without noticing the neutral and happy faces, due to a natural tendency to be aware of threats.

Availability Bias

The Availability Bias occurs when someone's prediction about an event's frequency or probability is unduly influenced by how easily they can recall examples of that event. We have a whole mini-course about combating availability bias.

Examples

• Ask yourself "Are there more English words that start with 'k' or that have 'k' as the third letter?" If you (like most people) guessed that there are more words that start with 'k', you were probably influenced by the fact that it's much easier to think of examples of those words. However, there are in fact more words with 'k' as the third letter!

• Suppose you're thinking about how flaky one of your friends is, and you recall that the last time you were going to hang out they canceled the last minute. It's easy to recall this example of the friend being flaky since it happened recently, but it's hard to remember that they didn't flake out any of the last ten hangouts you had with them before that, which may lead you to conclude they are flakier than they really are.

Bias Blind Spot

A Bias Blind Spot is a tendency to see oneself as being less biased or less susceptible to biases (such as those listed in this article) than others in the population.

Examples

• You might believe that reading this list made you immune to biases. It doesn't! Or you might think that because you can't immediately recall examples of yourself falling for different biases means you don't fall for them.

• As Julia Galef says in her book the Scout Mindset: "In fact, viewing yourself as rational can backfire. The more objective you think you are, the more you trust your own intuitions and opinions as accurate representations of reality, and the less inclined you are to question them. 'I'm an objective person, so my views on gun control must be correct, unlike the views of all those irrational people who disagree with me,' we think." -

Choice-Supportive Bias

Choice-Supportive Bias is a cognitive bias whereby someone who has chosen between different options later remembers the option that they chose as having more positive attributes than it did at the time (while they remember options they did not choose as having more negative attributes than they'd had at the time).

Examples

• Someone who chose to undertake an expensive and time-consuming course to gain a particular skill might retrospectively remember many positive aspects of the course they chose (even if these did not enter into their decision at the time), and remember the alternative options as being worse than they were (e.g., they might overestimate how unpleasant or difficult it would have been to learn the skill another way, to gain more work experience while still learning the skill, and so on).

• If you joined a fraternity that had both positive aspects (comradary with friends) and negative aspects (brutal hazing) you might, when thinking about how good the experience was as a whole, think more about the positive pleasant aspects (since the negative aspects are unpleasant to remember)

Confirmation Bias

Confirmation Bias refers to a tendency for people to seek out, favor, or give more weight to information that confirms their preconceptions or hypotheses (even if the information isn't true) than information that contradicts their prior beliefs.

Examples

• The spread of false news stories on social media is a great example of this type of bias. People are less likely to fact check stories that confirm their existing beliefs, and so share dubious stories without thinking carefully about them.

• If you believe that eggs are unhealthy, and you are in a disagreement with a friend who thinks they are healthy, you may google "why are eggs unhealthy?" that will be likely to lead you to websites that confirm your point of view, whereas if you searched "why are eggs healthy?" you'd likely end up with sites that contradict your point of view.

Denomination Effect

The Denomination Effect is a cognitive bias whereby people tend to be more likely to spend a given amount of money if it is composed of smaller individual sums than if it is composed of larger individual sums.

Example

• Imagine you pass a bakery. You might be more likely to buy five items that cost $1 each than 1 item that costs $5.

• If you have a $100 bill, you may be less likely to use it in a store than five $20 bills.

Hindsight Bias

Hindsight Bias refers to a tendency to perceive past events as being more predictable than they were before they took place.

Example

• You might think to yourself that you “had a bad feeling all along” when a decision you made didn't work out, when in fact you only experienced ordinary nervousness about making the decision.

• Suppose you thought about buying a stock but then decided not to buy it. If the stock suddenly goes up a lot in value you might think "I knew it was going to go up!" and think about all the reasons that it was likely to go up. On the other hand, if it had gone down a lot, you may have had similar thoughts like "I knew it was going to go down, that's why I didn't buy it!" and subsequently think about the various factors that suggested it might be a bad investment. Either way, you can convince yourself you knew all along what was going to happen!

Optimism Bias

Optimism Bias is the tendency to be unduly optimistic about the probability of future good and bad events, overestimating the probability of positive ones while underestimating the probability of negative ones.

Example

• If you are a smoker you might think "I know some people get lung cancer from smoking, but it's probably not going to happen to me!"

• You might know that the lottery is usually a bad investment, yet you might be overly optimistic about your personal chances of winning

Motivated Reasoning

Motivated reasoning occurs when you are disposed to interpret new evidence in ways that support your existing beliefs, or that lead to the outcome you wish was true, even when that evidence doesn't truly support your beliefs.

Example

• Someone reads an academic study containing data supporting the argument that a specific policy might help to reduce crime. However, since they don't support this policy, they construct an argument using the same data from the study, suggesting that it might increase crime.

• You would really not like it if the job you are having has a negative impact on the world, so you work to formulate an argument as to why your job as a loan shark is benefiting society.

Frequently Asked Questions (FAQ) about cognitive biases

What are the types of bias?

There are three main types of bias.

1. Explicit biases are prejudiced beliefs regarding a group of people or ways of living. Racism, sexism, religious intolerance, and LGBTQ-phobias are examples of explicit biases. If you think that all people of group X are inferior, then you have an explicit bias against people of group X.

2. Implicit biases are unconscious beliefs that lead people to form opinions or judgments, often without being fully aware they hold the unconscious beliefs. If you subtely distrust people of group X without even realizing you're doing it, then you have an implicit bias against people of group X.

3. Cognitive biases differ from explicit and implicit biases: they are a group of systematic patterns in how our beliefs, judgments, and actions differ from what they would if we were completely rational. If most people systemtaically misjudge certain types of information in such a way that you come to false conclusions, then people have a cognitive bias related to that type of information.

How many cognitive biases are there?

There is no consensus among academics regarding how many cognitive biases exist.Some have found ~40,others find >100, andWikipedia lists over 180.

What are the common causes of cognitive bias?

As we’ve seen above, cognitive biases often appear when one is faced with a decision and has limited resources (such as time, understanding, and cognitive capacity).

For instance, when buying a banana, you can't consider every single possible other use of that money to determine whether a banana is truly the single best use. You are limited in both how much time you have to think and how much total cognitive capacity you have.

Using fast heuristics or relying on our intuition is often an effective way of coming to conclusions in these situations because such approaches require fewer resources than careful thinking. While our intuition is often reliable, there are certain cases where our intuitions systematically produce inaccurate beliefs and unhelpful behaviors - these are what we refer to as "cognitive biases".

Even when we have plenty of time to think and aren't hitting a limit on our cognitive resources, people can still be prone to cognitive biases. For instance, there are certain automatic rules of thumb that our minds evolved to use since they worked quite well for the survival of our ancestors. Unfortunately, these rules of thumb can sometimes lead us to false conclusions and unhelpful behaviors in the modern world.

Is cognitive bias a good or bad thing?

Cognitive biases are not good or bad in themselves. They are an unavoidable effect of not having infinite intelligence and infinite time to think, and hence the need to rely on heuristics and intuition. We call a tendency a cognitive bias when it leads to systemic inaccuracies in our beliefs or unhelpful behaviors. In that sense, by definition, cognitive biases cause systematic problems.

However, cognitive biases do not always lead to negative outcomes in every instance. For instance, overconfidence may cause a person to try something very difficult, that they ultimately succeed at. On the other hand, for every one person who succeeds due to overconfidence, there may be multiple other people that try something that's unrealistic due to overconfidence and end up failing.

How do you identify cognitive biases?

Just knowing about specific cognitive biases is a great first step to identifying them in yourself, but knowledge of the biases is often not sufficient to cause you to identify them. Once you’ve done that, it can be helpful to get to know the most common cognitive biases (such as the ones presented above) so that you can look out for them in your own thinking.

Can you avoid cognitive bias?

Yes and no. It is possible to reduce the influence of cognitive biases on your thinking (and this can be very beneficial!). So you may be able to avoid a cognitive bias in many particular instances. But it's not possible to completely remove all of your cognitive biases.

How do you overcome cognitive biases?

Unfortunately, it’s impossible to overcome all of your cognitive biases completely. However, that doesn’t mean you can’t do anything. A good first step on the path to getting your cognitive biases under control is familiarizing yourself with them

Here are a few of our interactive tools that might help:

• The Planning Fallacy

• The Sunk Cost Fallacy

• Improve Your Frequency Predictions

• Political Bias Test

• Rhetorical Fallacies

• Are Your Overconfident?

• Calibrate Your Judgement

• How Rational Are You, Really?

• Metal Traps,

However, just knowing about your cognitive biases isn’t enough. You need to take action! Here are some practical steps we recommend:

• Biases such as overconfidence, confirmation bias, and the illusion of control can be reduced or avoided by having multiple points of view. Surrounding yourself and listening to people with diverse experiences, systems of beliefs, and expertise reduces the chances of falling into one of the said biases. This is also true for the source of information: it is less likely that you fall into a cognitive bias if you look for other data sources and conflict.

• Actively seeking evidence against your current point of view (on important decisions) can be a helpful way to combat biases like overconfidence, confirmation bias, and motivated reasoning.

Another strategy recommended by researchers who studied cognitive biases in physicians, is to consciously consider the options you dismissed at first, so you can reach a more considered answer.

What is a cognitive vs. an emotional bias?

Emotional biases can be considered a subcategory of cognitive biases. What separates them from other cognitive biases is that they are based on emotions such as anger, disgust, fear, happiness, sadness, and surprise. When we're experiencing emotions, we may act in a biased way that is concordant with that emotion. For instance, anxiety may cause us to overestimate the chance of something being dangerous.

Emotional biases are linked to emotional dispositions (commonly known as ‘temperament’). Different emotional dispositions may even lead to different emotional reactions to the same occurrence of events.

Emotional biases mayhelp us explain optimism and pessimism biases.

How do cognitive biases affect critical thinking?

Cognitive biases interfere with impartiality, and they can negatively impact critical thinking in a myriad of different ways. Here are several:

• Motivated reasoning leads us to underestimate the arguments for conclusions we don’t believe in and overestimate the arguments for conclusions we want to believe;

• Availability bias messes with our critical thinking because it leads us to asses risk by how readily examples come to mind, rather than considering all of the relevant examples;

• We are also prone to blind spot bias, meaning that we are less likely to identify biases in our own judgment than in other people's.

How do cognitive biases affect decision-making?

Cognitive biases affect decision-making in at least two ways: they help decision-making by speeding it up and cutting necessary corners when we have limited time or cognitive power, but they also hinder decision-making by causing us to come to false conclusions or take unhelpful actions in certain cases.

Is gender a factor for cognitive biases?

Research has shown some correlation between gender or sex and specific biases. For instance, researchers found that male investors tend to show greater overconfidence and optimism biases, while female investors tend to exhibit more anchoring and hindsight biases. The research makes no claims about what causes such gendered differences - e.g., socialization or biology or a mix of both.

Are gender stereotypes cognitive bias?

Gender stereotypes are explicit biases, which means they are not cognitive biases. However, there are many cognitive biases that involve gender stereotypes. For example, masculine bias is the tendency to assume a person is a male based on stereotypes after hearing gender-neutral information about them, and the tendency to use gender as a description only when describing women.

Gender stereotypes are also a sign of binary thinking.

Do cognitive biases cause depression?

Research has shown some cognitive biases are correlated with depression. This has been found to be the case for negative interpretation bias (the tendency to interpret ambiguous scenarios as negative) and pessimistic biases, which lead people to predict future situations as unrealistically negative.

Cognitive behavioral therapy is based on the assumption that individuals with depression have distorted negative beliefs about themselves or the world (known in CBT as "cognitive distortions").

Are cognitive biases scientific (is their existence scientifically proven)?

Yes. They have been studied since the early 1970s by cognitive psychologists, sociologists, and behavioral economists.

Do scientists exhibit cognitive biases?

Just like every other human being, scientists can exhibit cognitive biases.They may exhibit overconfidence bias or fall prety to selection biases, for example. This has been researched as it relates to the replication crisis social psychology faces today.

There is even research on the presence of cognitive biases in scientific contexts and occuring within academic publications. Nobody, not even scientists, are immune to cognitive biases!

Are cognitive biases learned? Or are we born with cognitive biases?

Both. We are born with a tendency for some cognitive biases, but we can also learn specific aspects of these biases. Our brains have evolved to be prone to all sorts of cognitive biases because those biases have been helpful in the survival of our ancestors in the environment (and under the constraints) in which they lived.

But the details of some specific cognitive biases are learned as we move through the world. For example, humans have evolved a tendency to engage in motivated reasoning, but which conclusions motivate your reasoning is something you aren’t born with and are impacted by your experiences and learning.

Keep learning by trying our mini-course on Mental Traps

Want to understand cognitive biases on a deeper level? Learn about a few of the mind's mistakes with our interactive introduction to cognitive biases!