What Is Cognitive Bias? 7 Examples & Resources (Incl. Codex)

defining cognitive biasesWe are often presented with situations in life when we need to make a decision with imperfect information, and we unknowingly rely on prejudices or biases.

For example, we might:

  • Trust someone more if they’re an authority figure than if they’re not
  • Assume someone’s gender based on their profession
  • Make poor decisions based on the information that we’re given

The reasons for our poor decision making can be a consequence of heuristics and biases. In general, heuristics and biases describe a set of decision-making strategies and the way that we weigh certain types of information. The existing literature on cognitive biases and heuristics is extensive, but this post is a user-friendly summary.

Central to this post’s topic is how cognitive heuristics and biases influence our decision making. We will also learn more about how to overcome them.

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What Are Cognitive Biases?

When considering the term ‘cognitive biases,’ it’s important to note that there is overlap between cognitive biases and heuristics. Sometimes these two terms are used interchangeably, as though they are synonyms; however, their relationship is nuanced.

In his book, Thinking, Fast and Slow, Professor Daniel Kahneman (2011, p. 98) defines heuristics as

a simple procedure that helps find adequate, though often imperfect, answers to difficult questions.

Tversky and Kahneman (1974, p. 1130) define the relationship between biases and heuristics as follows:

… cognitive biases that stem from the reliance on judgmental heuristics.

Gonzalez (2017, p. 251) also described the difference between the two terms:

Heuristics are the ‘shortcuts’ that humans use to reduce task complexity in judgment and choice, and biases are the resulting gaps between normative behavior and the heuristically determined behavior.

Lists and Types of Biases: The Codex

cognitive bias codexAccording to the Cognitive Bias Codex, there are an estimated 180 cognitive biases (this list is frequently updated.)

Created by John Manoogian III and Buster Benson, this codex is a useful tool for visually representing all of the known biases that exist to date.

The biases are arranged in a circle and can be divided into four quadrants. Each quadrant is dedicated to a specific group of cognitive biases:

  1. What should we remember?
    Biases that affect our memory for people, events, and information
  2. Too much information
    Biases that affect how we perceive certain events and people
  3. Not enough meaning
    Biases that we use when we have too little information and need to fill in the gaps
  4. Need to act fast
    Biases that affect how we make decisions

The Cognitive Bias Codex is a handy visual tool that organizes biases in a meaningful way; however, it is worth pointing out that the codex lists heuristics and biases both as ‘biases.’

If you decide to rely on the Cognitive Bias Codex, then keep in mind the distinction between heuristics and biases mentioned above.

4 Examples of Cognitive Biases

gambler's falacyThere are numerous examples of cognitive biases, and the list keeps growing. Here are a few examples of some of the more common ones.

1. Confirmation bias

This bias is based on looking for or overvaluing information that confirms our beliefs or expectations (Edgar & Edgar, 2016; Nickerson, 1998). For example, a police officer who is looking for physical signs of lying might mistakenly classify other behaviors as evidence of lying.

2. Gambler’s fallacy

This false belief describes our tendency to believe that something will happen because it hasn’t happened yet (Ayton & Fischer, 2004; Clotfelter & Cook, 1993).

For example, when betting on a roulette table, if previous outcomes have landed on red, then we might mistakenly assume that the next outcome will be black; however, these events are independent of each other (i.e., the probability of their results do not affect each other).

3. Gender bias

Gender bias describes our tendency to assign specific behavior and characteristics to a particular gender without supporting evidence (Garb, 1997).

For example, complaints of pain are taken more seriously when made by male, rather than female, patients (Gawande, 2014); women are perceived as better caregivers than men (Anthony, 2004); specific clinical syndromes are more readily diagnosed in women than in men (Garb, 1997); and students often rate female lecturers lower than male lecturers (MacNell, Driscoll, & Hunt; 2014; Mitchell & Martin, 2018).

4. Group attribution error

This error describes our tendency to overgeneralize how a group of people will behave based on an interaction with only one person from that group (Pettigrew, 1979).

For example, a negative experience with someone from a different group (e.g., a different culture, gender, religion, political party, etc.) might make us say that all members of that group share the same negative characteristics. Group attribution error forms part of the explanation for prejudice in social psychology.

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Examples in Business and Everyday Life

Gender bias in the workplace is a well-documented and researched area of cognitive bias. Women often do not occupy top senior positions. For example, in 2010, only 15.2% of top positions in US Fortune-500 companies were held by women (Soares, 2010). Women tend to earn less than their male counterparts, and women’s salaries differ according to their marital status.

For example, consider these statistics reported by Güngör and Biernat (2009, p. 232):

[In 2005]  … 68.1% of married and 79.8% of single mothers in the U.S. participate in the workforce, but while non-mothers earn 90 cents to a man’s dollar, mothers earn 73 cents, and single mothers earn about 60 cents.”

The social desirability bias is a concern for anyone who uses self-report data. Companies that run internal surveys investigating topics that may cast an employee in a poor light must be aware of how the social desirability bias will affect the validity of their data.

Knowing that people adjust their answers to appear more socially desirable, investigators (such as researchers and clinicians) can try to reframe their questions to be less direct, use formal tests, or anonymize responses.

Another sphere of our lives where biases can have devastating effects is in personal finance. According to Hershey, Jacobs-Lawson, and Austin (2012), there are at least 40 cognitive biases that negatively affect our ability to make sound financial decisions, thus hindering our ability to plan for retirement properly. Some of these biases include:

  • Halo effect (just because that real estate agent was nice doesn’t mean it’s a good deal)
  • Optimistic overconfidence (“I’ll be fine in the future, so I don’t need to save that much now.”)
  • Confirmation bias (looking for information to confirm or validate unwise financial decisions)

Role of Biases in Decision Making

Below you might find revealing insight into how biases affect our decision making.

The Monty Hall problem

the monty hall problemThis puzzle based on the American game show ‘Let’s Make a Deal’ is a good illustration of how biases affect our decision making.

Assume that there are three doors.

  • Behind one door is a fantastic prize: a car.
  • Behind the other two doors are mediocre prizes: $1,000.

You initially choose Door 1. Before revealing what’s behind your chosen door, the presenter opens a different door, Door 2, to reveal the mediocre prize. The presenter then gives you the option to either keep what’s behind your initial chosen door or change your choice, knowing what’s behind Door 2. What should you do now? Should you stay with your initial choice, Door 1, or should you switch to Door 3?

The correct answer is that you have the best chances of winning the car if you change your choice. This is called the Monty Hall problem. Here’s why you should switch:

  1. When you made your initial decision, you didn’t know what the outcome would be (mediocre prize versus awesome prize).
  2. After the host reveals more information, you have a better idea about which prizes are behind which doors.
  3. Based on this information, you’re more likely to find the car if you change your chosen door, an improvement from odds of 1 in 3 for your initial choice, to 2 in 3 if you switch.

Despite the statistics being in favor of switching, most people are hesitant to abandon their first choice and don’t accept the offer to change it.

Other cognitive biases

The Monty Hall problem is an excellent example of how our intuitions and heuristics lead us to make poor decisions. However, there are lots of other cognitive biases and heuristics that also affect our decision making.

Kahneman, Slovic, Slovic, & Tversky (1982) list 13 biases that arise from the following three heuristics:

  • Representativeness
    We think that the likelihood of two things happening is higher when the two things resemble or are similar to each other.

    • A cognitive bias that may result from this heuristic is that we ignore the base rate of events occurring when making decisions. For example, I am afraid of flying; however, it’s more likely that I might be in a car crash than in a plane crash. Despite this, I still hate flying but am indifferent to hopping into my car.
  • Availability
    We tend to overestimate how likely something is to happen based on how easily we can remember the same thing happening previously.

    • For example, when a violent crime occurs in a neighborhood, neighbors in that neighborhood will give a bigger estimate of the frequency of these crimes, compared to the reported statistics. The reason for their overestimate is that the memory of the violent crime is easy to retrieve, which makes it seems like violent crime happens more frequently than it actually does.
  • Adjustment and anchoring
    Our decisions, and the changes to our decisions, are influenced by the first bit of information that we’re given.

    • For example, assume that I offer to sell you a car and I ask for $250. You counter with $200. You might think that this is a good deal because you bought the car for less than the asking price; however, your counteroffer was heavily influenced by my asking price, and you’re not likely to deviate too much from it.

2 Popular Experiments

To further illustrate the effect of cognitive bias, below are two popular experiments.

1. Anchoring and adjustment

Tversky and Kahneman (1974) found that our estimates are heavily influenced by the first number given to us. For example, participants were asked to estimate the percentage of African countries in the United Nations.

Before giving their answer, each participant had to spin a ‘Wheel of Fortune,’ which would determine their initial starting percentage. The result of the ‘Wheel of Fortune’ was random and meaningless. Despite this, participants’ estimate of African UN member-countries didn’t differ much from whatever random ‘Wheel of Fortune’ amount they landed on, regardless of what that amount was.

2. The attractiveness halo effect

Male students were asked to rate essays written by female authors (Landy & Sigall, 1974). The quality of the essays varied: some were poorly written, and others were well written.

Additionally, some of the essays were accompanied by a photograph of the author (who was either attractive or unattractive), and others were not. Male college students rated the quality of the essay and the talent of the authors higher when:

  • the essay was written by an attractive author, and
  • this effect was evident only when the essay was of poor quality.

In this study, the male students demonstrated the halo effect, applying the perceived attractiveness of the female author to the quality of the paper.

4 Ways to Overcome Your Biases

ways to overcome cognitive biasHere is a list of four methods that you can use to overcome your own biases.

1. Reflect on past decisions

If you’ve been in a similar situation before, you can reflect on the outcomes of those previous decisions to learn how to overcome your biases.

An example of this is budgeting. We tend to underestimate how much money we need to budget for certain areas of our life. However, you can learn how much money to budget by tracking your expenditure for the last few months. Using this information from the past, you can better predict how much money you’ll need for different financial categories in the future.

2. Include external viewpoints

There is some evidence that we make better decisions and negotiations when we consult with other people who are objective, such as mediators and facilitators (Caputo, 2016).

Therefore, before making a decision, talk to other people to consider different viewpoints and have your own views challenged. Importantly, other people might spot your own cognitive biases.

3. Challenge your viewpoints

When making a decision, try to see the weaknesses in your thinking regardless of how small, unlikely, or inconsequential these weaknesses might seem. You can be more confident in your decision if it withstands serious, critical scrutiny.

4. Do not make decisions under pressure

A final way to protect yourself from relying on your cognitive biases is to avoid making any decisions under time pressure. Although it might not feel like it, there are very few instances when you need to make a decision immediately. Here are some tips for making a decision that can have substantial consequences:

  1. Take the necessary time to ruminate.
  2. List the pros and cons.
  3. Talk to friends or family members for advice (but remember that they may have their own biases).
  4. Try to poke holes in your reasoning.

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Bias Modification Exercises and Activities

In the last decade, research has looked at cognitive bias modification (CBM) since cognitive biases are associated with the severity of anxiety and depression. The relationship between cognitive biases and anxiety and depression is assumed to be causal; that is, cognitive biases cause an increase in the severity of symptoms.

CBM exercises are designed with this causal relationship in mind. If the cognitive bias is removed or reduced, then the severity of the symptoms should also lessen.

There are two categories of CBM exercises:

  1. Changing attentional bias: In this type of exercise, participants are trained to pay more attention to positive stimuli instead of negative stimuli.
  2. Changing interpretation bias: Participants are primed with positive information before completing an emotionally ambiguous task.

At least six meta-analyses report conflicting findings (Beard, Sawyer, & Hofmann, 2012; Cristea, Kok, & Cuijpers, 2015; Hakamata et al., 2010; Hallion & Ruscio, 2011; Heeren, Mogoașe, Philippot, & McNally, 2015; Mogoaşe, David, & Koster, 2014).

There are many reasons for these differences; for example, the types of studies included, the moderators included, the definition of the interventions, the outcome variable used, the clinical condition studied, and so forth. Therefore, the jury is still out on whether CBM affects symptom severity reliably.

A Look at Cognitive Bias Modification Apps

There are many cognitive bias modification apps available for download. Before purchasing an app, research whether the creator of the app has followed sound research principles or done any research when developing the app (Zhang, Ying, Song, Fung, & Smith, 2018).

Most of the bias modification apps aim to change the attentional bias. For example, the following apps aim to train users to respond quicker to happy faces than to sad or angry faces. All hypothesize that repeated use will result in more positive moods.

The Cognitive Bias Cheatsheet is a useful way to remind oneself of the different cognitive biases that exist.

5 Relevant Books

Here is a list of books relevant for anyone interested in cognitive biases.

Firstly, any list about biases would be remiss without Thinking, Fast and Slow by Daniel Kahneman (2011). In this book, Kahneman unpacks some of the most common biases that we experience when making decisions. (Available on Amazon)

In the same vein is The Drunkard’s Walk: How Randomness Rules Our Lives by Leonard Mlodinow (2009). This book addresses how humans misjudge the effect that randomness has on our decision making. (Available on Amazon)

Predictably Irrational by Dan Ariely (2008) is an excellent and very accessible book about how our behavior is often governed by seemingly random and illogical thought processes. The opening chapter is jaw dropping. (Available on Amazon)

Nassim Nicholas Taleb published a series of books – five, in fact – and I include two of them on this list: Fooled by Randomness (2005) and The Black Swan (2007). The entire series discusses various aspects of uncertainty. (Available on Amazon)

Our Favorite TED Talks on the Topic

We’ve put together a list of our favorite impressive TED talks on cognitive biases.

If you want to learn more about cognitive biases, then these talks are a great jumping-off point:

Are We in Control of Our Own Decisions? – Dan Ariely

Confirmation Bias – Nassor Al Hilal

Confirmation Bias in 5 Minutes – Julia Galef

If you want to learn how to overcome your biases, then we can recommend the following:

How to Outsmart Your Own Unconscious Bias – Valerie Alexander

How to design gender bias out of your workplace – Sara Sanford

Unpacking the biases that shape our beliefs – Mike Hartmann

Resources From PositivePsychology.com

We have useful resources that you can use when tackling cognitive biases.

First, increasing awareness of Unhelpful Thinking Styles can change the way you think about yourself and your environment. Ultimately, users will increase their awareness of their cognitive biases, and through this awareness, be able to change their behavior.

Our Neutralizing Judgmental Thoughts worksheet is also useful for combating negative thoughts and biases. This exercise helps users apply the CLEAR acronym to adopt a less critical outlook when dealing with others.

The Core Beliefs Worksheet is a useful tool for reflecting on the origin and validity of our core beliefs. This technique might help us ‘step away’ from our biases.

An approach that is always beneficial, is to understand and find ways to apply positive psychology to your every day, and this selection of positive psychology TED Talks is a good starting point.

If you’re looking for more science-based ways to help others through CBT, this collection contains 17 validated positive CBT tools for practitioners. Use them to help others overcome unhelpful thoughts and feelings and develop more positive behaviors.

17 Science-Based Ways To Apply Positive CBT

These 17 Positive CBT & Cognitive Therapy Exercises [PDF] include our top-rated, ready-made templates for helping others develop more helpful thoughts and behaviors in response to challenges, while broadening the scope of traditional CBT.

Created by Experts. 100% Science-based.

A Take-Home Message

We often rely on cognitive heuristics and biases when making decisions.

Heuristics can be useful in certain circumstances; however, heuristics and biases can result in poor decision making and reinforce unhealthy behavior.

There are many different types of cognitive biases, and all of us are victim to one or more.

However, being aware of our biases and how they affect our behavior is the first step toward resisting them.

We hope you enjoyed reading this article. For more information, don’t forget to download our three Positive CBT Exercises for free.


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What our readers think

  1. Joseph

    It’s truly appreciated your efforts I am sure this is going to be of immense help in my lectures to diploma students

  2. Thom Moore

    Dumb. I wish the author would have used the “4 Ways to Overcome Bias” prior to writing this irrelevant article. Then maybe the contradictions could have been avoided such as the codex containing both heuristics and biases or the gender bias and marital status. Leading off with gender bias, by the way, is a dead giveaway that this is just propaganda disguised as pseudo-intellectual tripe. The author painted the issue as “women make less, so = bias.” Allow me to use the group attribution bias and call this as another article from majority female psychology “profession.”

  3. Alex

    I agree that awareness of our biases is the first step to overcoming them. But I think it’s important to also understand that we all have biases, and that they’re not necessarily a bad thing. We need biases to make decisions, and without them we would be paralyzed. The key is to be aware of our biases and to try to overcome them when they lead us astray.

    • Bruce

      You may be conflating heuristics with bias. Heuristics are shortcuts to see pattern and simplify things based on our experience and intuition. Heuristics are needed to make decisions and solve problems. But heuristics are also prone to thinking errors. Biases are thinking errors.

  4. Elizabeth Cortez

    Thank you for this feast of information that I will be savoring over and over for weeks.

  5. Cynthia Braccini

    Thank you very much for the detailed information and resources. I plan to utilize this as a link with certain highlighted components for my social psychology unit with my students.





  7. Chris Sanders

    Thanks for the detailed blog. I’m going to provide this as a link on my critical thinking course that I teach at a university.


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