Cognitive Biases: What They Are and How They Affect People

Cognitive Biases


A cognitive bias is a systematic pattern of deviation from rationality, which occurs due to the way our cognitive system works. Accordingly, cognitive biases cause us to be irrational in the way we search for, evaluate, interpret, judge, use, and remember information, as well as in the way we make decisions.

For example, one well-known cognitive bias is the illusion of transparency, which causes us to believe that our thoughts and emotions are more apparent to others than is actually the case. We experience this bias because when we try to assess how other people see us, it’s hard for us to adjust from the anchor of our own perspective.

Cognitive biases affect every area of our life, from how we form our memories, to how we shape our beliefs, and to how we form relationships with other people. In doing so, they can lead to both relatively minor issues, such as forgetting a small detail from a past event, as well as to major ones, such as choosing to avoid an important medical treatment that could save our life.

Because cognitive biases can have such a powerful and pervasive influence on ourselves and on others, it’s important to understand them. As such, in the following article you will learn more about cognitive biases, understand why we experience them, see what types of them exist, and find out what you can do in order to mitigate them successfully.


Examples of cognitive biases

One example of a well-known cognitive bias is the halo effect, which is a cognitive bias that causes our impression of someone or something in one domain to influence our impression of them in other domains. The halo effect means, for example, that when we think someone is physically attractive, we tend to believe that they are also more knowledgeable and have a better personality compared to what we would think if they were unattractive.

Another example of a cognitive bias is the illusion of control, which is a cognitive bias that causes us to overestimate our ability to control the outcome of situations where chance plays a greater role than skill. The illusion of control means, for example, that we might overestimate our ability to succeed in a risky business venture, even if that venture is likely to fail regardless of how much effort we put into it.

Another example of a cognitive bias is the outgroup homogeneity bias, which causes people to perceive members of outside groups as being more similar to one another than members of groups that they are a part of. This happens primarily because people tend to allocate more of their attention to members of their own group, since interactions with those people are often perceived as more important.

In addition, other examples of cognitive biases include the following:

  • The rhyme-as-reason effect. The rhyme-as-reason effect is a cognitive bias that makes people more likely to remember, repeat, and believe statements that contain a rhyme, compared to those that do not. For example, people generally perceive the aphorism “woes unite foes” as more accurate than the aphorisms “woes unite enemies” or “misfortunes unite foes”, despite the fact that they all mean roughly the same thing.
  • The zero-sum bias. The zero-sum bias is a cognitive bias that causes people to mistakenly view certain situations as being zero-sum, meaning that they incorrectly believe that one party’s gains are directly balanced by other parties’ losses. For example, the zero-sum bias can cause people to think that there is competition for a resource that they feel is limited, in situations where the resource in question is actually unlimited and freely available.
  • The fundamental attribution error. The fundamental attribution error is a cognitive bias that causes people to underestimate the influence of environment-based situational factors on people’s behavior, and to overestimate the influence of personality-based dispositional factors. For example, the fundamental attribution error can cause someone to assume that if some stranger looks angry, then they must be an angry person in general, even though this person might have been driven to temporary anger by something, such as someone else being rude to them.

Finally, examples of cognitive biases also appear in specific domains. For instance:

  • When it comes to entrepreneurship, cognitive biases can cause entrepreneurs to be overly confident and optimistic regarding their business ventures.
  • When it comes to medicine, cognitive biases can cause doctors to misdiagnose patients who are displaying symptoms that are atypical for their condition.


Who experiences cognitive biases

Because cognitive biases occur due to the way our basic cognitive system works, every person experiences cognitive biases to some degree, including professional psychologists. Furthermore, cognitive biases occur not only in humans but also in animals, such as bees, pigs, and dogs.

However, people tend to be less aware of their own biases than of those of others, and to assume that they’re less susceptible to biases than others, a phenomenon known as the bias blind spot.


Factors affecting cognitive biases

Various background factors, such as age and culture, can affect the degree to which people experience certain cognitive biases, leading to significant individual variation.

However, the relationship between these background factors and the occurrence of cognitive biases is complex. For example, general cognitive ability is associated with the likelihood that people will experience certain biases, but not all of them. Furthermore, even in cases where there is an association between cognitive ability and the likelihood of biases, the strength of this association varies based on the bias in question.


Why people experience cognitive biases

There is no single cause for all cognitive biases. However, research suggests that cognitive biases occur primarily due to faulty intuitions or improper analytical reasoning. These issues, in turn, are attributed to various causes, such as the desire to confirm preexisting beliefs in order to avoid psychological discomfort, or the difficulty associated with quickly processing large amounts of information.

Specifically, many explanations of cognitive biases are based on dual-system theory, which suggests that we use two main cognitive systems:

  • System 1. This system is responsible for our intuitive processing, which is relatively fast, automatic, and effortless. Accordingly, processes on this system run in parallel, meaning that it’s possible to engage this system on multiple fronts simultaneously. This system tends to be relatively strongly influenced by emotions. An example of a situation where System 1 is engaged is when we feel pleased because someone laughed at a joke that we told.
  • System 2. This system is responsible for our conscious reasoning, which is relatively slow, controlled, and effortful. Accordingly, processes in this system run in a serial manner, meaning that this system can only focus on one thing at a time. This system tends to be relatively detached from emotional considerations. An example of a situation where System 2 is engaged is when we try to solve a complex mathematical equation.

Under this framework, a common cause of cognitive biases is people’s reliance on intuition (System 1) in situations where analytical reasoning (System 2) is needed. This can happen because intuition is relatively fast and easy to use, and can lead to outcomes that are as good as or better than analytical reasoning in many cases, so people rely on it even when it’s not appropriate to do so.

For example, in one experiment, university students were asked a simple brain teaser:

“A bat and a ball cost $1.10 in total. The bat costs $1 more than the ball. How much does the ball cost?”

Upon hearing this question, many of them felt an initial tendency to answer “10 cents”, because the total sum of $1.10 separates naturally into $1 and 10 cents, so that that the answer “10 cents” sounds about right. The problem is that over half the people in the experiment ended up sticking with this initial estimate, leading them to answer this question incorrectly, since the right answer is that the bat costs $1.05, while the ball costs $0.05 (5 cents).

Essentially, what happened here is that most people made an intuitive assessment of the situation using System 1, and got an answer that was close to the correct one, which would have been good enough for certain situations, such as those where an approximation was needed. Some people then used System 2 to assess this initial answer, which generally allowed them to realize that it’s incorrect, and which consequently led them to calculate the correct answer. However, other people failed to engage System 2 properly or at all, which meant that they ended up relying on the incorrect initial assessment that they got from System 1.

Overall, based on the dual-system theory, cognitive biases occur primarily for two main reasons:

  • System 1 generates a faulty intuition and System 2 fails to correct it, either because System 2 fails to go into action, or because System 2 goes into action but fails to properly inhibit or supervise System 1.
  • System 2 fails to engage in proper analytical reasoning.

These issues, in turn, can be attributed to various causes, such as a desire to avoid finding out that you were wrong, due to the psychological discomfort that’s often involved.

For example, the confirmation bias is a cognitive bias that causes people to search for, favor, interpret, and recall information in a way that confirms their preexisting beliefs. This bias can occur, for instance, when people intuitively dismiss important information without consideration (based on System 1), because they suspect that it could disprove their beliefs. Similarly, it can also occur when people analyze information in-depth (using System 2), but ignore any aspects of it that contradict their beliefs.

Note that there is some disagreement regarding the exact mechanisms responsible for cognitive biases. For example, some researchers argue in favor of dual processes, rather than systems, or in favor of further levels of processing. Furthermore, some researchers suggest that different mechanisms, such as noisy information processing, may underlie certain cognitive biases.

Nevertheless, many of these theories share much in common, and as such, the information in this section provides a helpful outline for people interested in the topic, and especially for those interested in understanding the concept of cognitive biases from a practical perspective.


Bounded rationality, satisficing, and heuristics

When understanding why people experience cognitive biases, there are several additional concepts that are helpful to understand:

  • Bounded rationality. Bounded rationality is the idea that our judgment and decision-making abilities are constrained by the limitations of our cognitive systems, and depend on the type of information that we need to process, as well as on the amount of time that we have in order to do so. This means that when we try to solve a problem, we often end up reaching a solution that is different from the one we would reach if our cognitive systems were perfect, or from the one that we would reach if we had more time to consider the problem. Cognitive biases are a notable feature of our bounded rationality.
  • Satisficing. Satisficing, which is a blend of the words sufficing and satisfying, represents the willingness to pass judgments and make decisions that are good enough given the circumstances, rather than perfect. It is therefore contrasted with maximizing, which is the preference for finding the absolute best course of action. Satisficing can lead us to experience a variety of cognitive biases.
  • Heuristics. Heuristics are mental shortcuts that help us assess information and make decisions relatively quickly and easily. For example, if we are asked how many apples there are in a basket, then instead of counting all the apples individually, we can apply a heuristic, and see how much room 4 apples take, and then estimate how many groups of 4 apples there are in the basket. Heuristics, which are associated primarily with System 1, are generally seen as a form of satisficing, and stand at the core of many cognitive biases. This includes, for example, biases such as the availability heuristic and the representativeness heuristic.


Additional information about our cognitive systems

When understanding our cognitive systems, in the context of cognitive biases, there are two additional concepts that can be useful to understand.

First, which System is engaged at any given time depends on factors such as a person’s skill level and the circumstances. For example, skilled drivers are often able to talk while driving, which indicates that for them, driving is intuitive, since it’s difficult to perform two System 2 processes simultaneously, as we saw above. However, even the most experienced drivers will generally struggle to talk if they’re driving in rough conditions, which require their full attention.

Second, our perception system, which is responsible for our ability to perceive input, is considered to be distinct from our two other cognitive systems (System 1 and System 2). Though there are some similarities between our perception system and System 1, since they both consist primarily of automatic processes that run in parallel to each other, there are some key differences between them:

  • Our perception is relatively neutral, while System 1 is influenced by various emotional considerations.
  • Our perception is evoked by direct stimulus only, while System 1 can be evoked by things such as thoughts.
  • Our perception is limited to perceptual representations, while System 1 can generate abstract representations.
  • Our perception is limited to stimuli that we encounter in the present, while System 1 can also deal with information that relates to the past or the future.

Our perceptual system provides us with information that is fed into System 1, in order to form intuitive impressions. Then, these impressions undergo deliberate operations of reasoning by System 2, in order to form conscious judgments.


Types of cognitive biases

Various criteria have been used to categorize the different types of cognitive biases, and there is no single, agreed-upon scheme for this. However, biases are often categorized based on the general aspect of people’s judgment and decision-making that they affect. Based on this, the main types of biases are the following:

  • Calculation biases. These are biases that affect the way in which we calculate things such as probabilities or values. For example, the gambler’s fallacy is a cognitive bias that causes people to mistakenly believe that if something happens more frequently than normal during a given time period, then it will happen less frequently in the future. This occurs because people believe that a short sequence of random independent events should be representative of a longer sequence of such events.
  • Information biases. These are biases that affect the way in which we acquire and process information. For example, the contrast effect is a cognitive bias that distorts our perception of something when we compare it to something else, by enhancing the differences between them. The main reason why people experience this bias is that we often make comparisons when evaluating information, even if those comparisons are irrelevant and detrimental.
  • Belief biases. These are biases that affect the way in which we form our beliefs and modify them. For example, the false-consensus effect is a cognitive bias that causes people to overestimate the degree to which their beliefs, values, characteristics, and behaviors are shared by others. Essentially, this means that the false consensus effect leads people to assume that others think and act in the same way that they do, even when that isn’t the case.
  • Memory biases. These are biases that affect the way we create, retain, and recall memories. For example, rosy retrospection is a cognitive bias that causes people to remember past events as being more positive than they were in reality. This occurs primarily because people tend to forget negative and neutral parts of certain past experiences, which causes those experiences to appear more positive.
  • Social biases. These are biases that affect our social perception and behavior. For example, the spotlight effect is a cognitive bias that causes people to think that they are being observed and noticed by others more than they actually are. This occurs because people naturally see everything from their own point of view, so they struggle to accurately judge how they look through other people’s eyes.

Note that some biases can affect multiple types of processes. For example, the bandwagon effect is a cognitive bias that causes people to do something because they believe that other people are doing the same thing. It is a social bias, but it can affect people in various domains, such as when it comes to their beliefs or their memory.


Hot and cold biases

Biases are sometimes categorized based on whether they’re considered hot or cold:

  • Hot biases are biases that are motivated by emotional considerations, such as our desire to have a positive self-image. For example, the self-serving bias is a cognitive bias that causes people to take credit for their successes and positive behaviors by attributing them to dispositional factors, and to deny responsibility for failures and negative behaviors by attributing them to situational factors. This bias occurs primarily due to people’s need to enhance their self-esteem, and is strongly influenced by various emotional considerations.
  • Cold biases are biases that occur due to emotionally-neutral processes, such as limitations of our cognitive capacity. For example, the telescoping effect is a cognitive bias that causes people to perceive past events as being more recent than they are, and recent events as being more remote. This bias occurs due to the way our memory works, and isn’t generally affected by any emotional considerations.

Accordingly, the difference between hot and cold biases is that hot biases are emotionally motivated, whereas cold biases are not. However, this distinction is imperfect, since it is sometimes difficult to establish whether a certain bias is hot or cold, either in general or under particular circumstances.

For example, the hindsight bias causes people to overestimate how predictable a past event was, once they already know its outcome. The hindsight bias can occur due to “hot” reasons, such as when a person wants to believe that they were smart enough to have predicted what was going to happen. However, the hindsight bias can also occur due to “cold” reasons, such as when a person struggles to ignore information that they have available to them in the present, when trying to assess their mindset in the past.

Nevertheless, despite the limitations of the hot/cold distinction when it comes to cognitive biases, it can be useful in some cases, such as when a certain bias is clearly “hot” or clearly “cold”.


Cognitive debiasing

The problem with cognitive biases

As we saw so far, cognitive biases can be problematic, because they can distort our thinking and cause us to form bad judgments and make bad decisions.

For example, the ostrich effect is a cognitive bias that causes people to avoid information that they perceive as potentially unpleasant. This means that this bias can cause you to avoid acquiring important information, such as information on how to deal with a medical condition that you have. Being able to mitigate the ostrich effect is therefore important, since it can prompt you to acquire useful information that you would otherwise avoid.

Accordingly, learning how to debias can be beneficial in many situations, both when it comes to helping yourself thinking more clearly, as well as when it comes to helping others do the same.


Reducing and avoiding cognitive biases

As we saw earlier, cognitive biases occur as a result of two main issues with our cognitive system:

  • Failure of System 1 (our intuitive system) to generate correct intuitions, together with a failure of System 2 (our analytical system) to supervise or inhibit System 1.
  • Failure of System 2 to conduct a proper reasoning process.

Based on this, there are two main things that you can do in order to mitigate cognitive biases:

  • Help System 1 generate better intuitions. You can do this in various ways. For example, in the short-term, you can improve the environment where you form the intuitions, while in the long term, you can practice the formation of intuitive impressions, while providing System 1 with feedback that helps it improve.
  • Help System 2 supervise System 1 and conduct a proper reasoning process. You can do this in various ways, such as by improving your decision-making environment and slowing down your reasoning process.

Most commonly, to avoid and reduce cognitive biases, you will need to implement various debiasing techniques. Most of these techniques revolve around your metacognition, which is the awareness and understanding of your thought process, and because this generally requires conscious efforts, they primarily have to do with improving the functioning of System 2.

Some debiasing techniques are relatively simple and universal; this includes, for example, simply increasing your knowledge of relevant biases, and keeping them in mind where relevant. Other techniques are more specific; this includes, for example, creating psychological self-distance in order to mitigate the egocentric bias, which is a cognitive bias that causes people to rely too heavily on their own point of view when they examine events in their life or when they try to see things from other people’s perspective.

The effectiveness of debiasing techniques varies based on the bias in question. For example, consider the anchoring bias, which causes people to over-rely on an initial piece of information during subsequent judgments. Debiasing is generally much less effective when the anchoring occurs as a result of an explicit comparison between the anchor and a subsequent piece of information, meaning that it’s harder to reduce this bias when the comparison to the anchor is one that the person was explicitly asked to make.

Overall, this section describes the basic principles behind cognitive debiasing. If you would like to learn more about how to debias yourself and others effectively, you should read the dedicated article on the topic.


Additional information

Cognitive biases aren’t always bad

Though cognitive biases are examples of irrationality, they do not always affect us in a negative manner. Rather, cognitive biases can sometimes influence our thought process in a positive way, that helps us make optimal decisions.

For example, the pessimism bias is a cognitive bias that causes people to overestimate the likelihood of negative things and underestimate the likelihood of positive things, especially when it comes to assuming that future events will have a bad outcome.

This bias can negatively impact people in some cases, such as when it causes them to avoid making an effort, by leading them to assume that they will inevitably fail. However, the pessimism bias can also positively impact people in some cases, such as when it causes them to properly prepare for the future, by leading them to believe that they are likely to encounter difficult challenges.

Furthermore, many biases serve as useful mental shortcuts, that help people simplify complex problems and make decisions quickly, which can be beneficial in many cases, even if it means that they don’t make the best possible decision in every situation.

Finally, cognitive biases can also be beneficial in other ways. From an individual perspective, for example, cognitive biases can help people make optimal decisions when uncertainty is involved. Similarly, from a group perspective, cognitive biases can encourage people to help each other.

Overall, though cognitive biases can negatively impact people in various ways, they can also be beneficial in some cases. This is true both on an individual scale, such as when biases encourage people to prepare for the future, and on a group scale, such as when biases encourage cooperation. Accordingly, from an evolutionary perspective, cognitive biases are sometimes viewed as adaptive features rather than maladaptive flaws.

Because of this, it’s important to understand that cognitive biases can sometimes help you to make optimal decisions, even if they distort your view of the situation. At the same time, however, it’s still important to be aware of them, so that you can understand how they affect you, and determine whether you will benefit from reducing their influence.

Note: when discussing the potential value of cognitive biases, some researchers draw a distinction between cognitive biases as an “inaccurate view of the world” and outcome biases as “a departure from rational behavior”. Under this distinction, a cognitive bias “might produce rational behaviour or might result in an outcome bias”.


The difference between cognitive biases and logical fallacies

While cognitive biases and logical fallacies are similar, they represent two distinctly different things:

  • Cognitive biases involve systematic errors in cognition, and are therefore a psychological concept.
  • Logical fallacies involve flawed patterns of argumentation, and are therefore a philosophical concept.

Cognitive biases generally occur at a more basic level of thinking, particularly when they’re rooted in people’s intuition, and they can lead to the use of various logical fallacies.

For example, consider the appeal to nature, which is a logical fallacy where something is claimed to be good because it’s perceived as natural, or bad because it’s perceived as unnatural. This fallacy can sometimes be rooted in certain cognitive biases, that cause people to instinctively prefer things that they perceive as being natural.

Furthermore, in some cases, certain logical fallacies, and particularly those that are employed for rhetorical purposes, can take advantage of people’s cognitive biases, in order to amplify their rhetorical power.

For example, consider slippery slope arguments, which are argument that suggests that a certain initial action could lead to a chain of events with a relatively extreme result, or that if we treat one case a certain way then we will have to treat more extreme cases the same way too. Someone using such arguments might take advantage of people’s pessimism bias, in order to make them believe that the conclusion of a fallacious slippery slope argument is more likely than is actually the case.

However, this doesn’t mean that the use of logical fallacies is always associated with related cognitive biases.

For example, consider strawman arguments, which are fallacious arguments that distort an opposing stance in order to make it easier to attack. While someone might use a strawman argument because they misunderstand their opponent’s argument due to some cognitive bias, it’s also entirely possible to use such arguments consciously, while being aware that you are doing so, and without being driven to it by any cognitive bias or trying to get someone else to experience a bias either.

Overall, the main distinction between cognitive biases and logical fallacies is that biases are a psychological concept, that has to do with cognition, while fallacies are a philosophical concept, that has to do with argumentation. Cognitive biases are sometimes associated with certain fallacies, such as when a cognitive bias leads to the use of a fallacy, or when a fallacy’s rhetorical effectiveness relies on an underlying bias, but each of these phenomena can appear on its own.

Note: logical fallacies are often described as flawed patterns of reasoning, rather than argumentation. The term ‘argumentation’ is used here to emphasize that fallacies have to do with a different type of reasoning than cognitive biases.


The history of cognitive biases

Though cognitive biases have affected humans and other animals from an early stage of our development, this concept was formalized and popularized in the early 1970s by two researchers, Daniel Kahneman and Amos Tversky, in a series of papers on the topic. These initial papers, which deal with systematic irrationality in general and with the concept of cognitive biases in particular, include the following:

The two earlier papers served primarily to introduce the concept of heuristics under the framework described by Kahneman and Tversky, while the 1974 paper became the most-cited article on the topic, and introduced cognitive biases as we know them today.

Kahneman went on to win the 2002 Nobel Prize in Economics for his joint work with Tversky, who died in 1996.

To learn more about the history of cognitive biases, you should read Kahneman’s famous book on the topic: “Thinking, Fast and Slow“. If interested, you can also read the book written about Kahneman and Tversky: “The Undoing Project: A Friendship That Changed Our Minds“, or the review of the book published in The New Yorker.


Summary and conclusions

  • A cognitive bias is a systematic pattern of deviation from rationality, which occurs due to the way our cognitive system works.
  • Cognitive biases cause us to be irrational in the way we search for, evaluate, interpret, judge, use, and remember information, as well as in the way we make decisions.
  • Various factors, such as age and culture, can affect the way people experience cognitive biases, but everyone experiences biases to some degree, including professional psychologists.
  • Many different theories have been proposed to explain why we experience biases; a notable one is the dual-system theory, which generally suggests that we experience biases because of faulty intuitions that our analytical system fails to correct, or because our analytical system fails to conduct a proper reasoning process.
  • Cognitive biases can lead to problems with our judgment and decision-making, but it is possible to reduce and avoid them in various ways, including, most notably, through the use of relevant debiasing techniques.

If you want to read more about this topic, you want to learn more about the concept of cognitive biases, the best book on the topic is “Thinking, Fast and Slow“, by Daniel Kahneman, the Nobel laureate who first described the concept.

In addition, two other recommended books are “Predictably Irrational” and “The Art of Thinking Clearly“, which will help you learn more about common biases and patterns of irrationality that people display.