9 Common Thinking Biases

Our thought processes are not always the clearest. They are not always the most rational. Psychologists have identified over 100 of these thinking biases. This blog looks at just nine of these, which seem particularly relevant to the world of both education and sport, and offers tips on how best to overcome them.

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Confirmation Bias – this refers to the idea that people pay more attention to people or ideas that they had previously agreed with. A great example of this is illustrated in Daniel T. Willingham’s excellent book, ‘When Can You Trust The Experts’. He details a fascinating study in which half a class of students were told that their supply teacher was ‘rather cold, industrious, critical, practical and determined’. The other half were told the exact same sentence, except the words ‘rather cold’ were replaced with ‘very warm’.

Students who had expected to be taught by a warm teacher rated the supply teacher as nicer and funnier. In other words, what they saw and interpreted backed up their previous belief.

  • How to Overcome This? Have a diverse range of people to talk to. This range of personalities can help avoid group-think and help minimise confirmation bias.

The Halo Effect – this describes how your overall impression of someone is influenced by either one part of their character or your first opinion of them. For example, if a student gets an A on their first essay, or an athlete scores on their debut, it is easy to assume that they are high achieving/potential individuals, and so therefore would expect them to achieve similar success in the future. However, this is a sample size of 1. There is not enough information to make a reliable prediction.

This short video clip of Derren Brown gives an example of the halo effect in action, in social situations:

  • How to Overcome This? Remember that first impressions may not be the most accurate. Try not to have too fixed an opinion too early on and see things not just as black or white, awful or amazing, successful or unsuccessful.

The Hawthorne Effect – This is named after an experiment at The Hawthorne Factory in America. Keen to find out how their staff could be more productive, the owners of the factor observed them. When they were being watched, productivity increased. When they were no longer being observed, productivity returned to normal rates.  This has some interesting implications, as it is difficult to give someone feedback on how they are doing, if your mere presence alters how they go about doing their work.

  • How to overcome it? Take a long term approach. One off observations are probably fairly useless. Where possible, make these as discrete and subtle as possible, to minimise the impact of your presence there.

Negativity Bias – Let’s do a quick experiment: I think you are a kind person but I also think some of your suggestions are stupid. If I was to ask you which part of the sentence you would be likely to remember in a months time, chances are it would be the negative part. This is because we have learnt to play close attention to the negative things. This probably has evolutionary backgrounds where being aware of negative and harmful things helped keep us safe.

  • How to Overcome This? Take time to actively search out and reflect on the good things that have happened. It is unlikely that everything is all bad. Check out our blog on challenging unhelpful thoughts.

The Bandwagon Effect: This describes how you are more likely to believe in an idea if lots of other people already believe it. For example, people are far more likely to re-use their hotel towel if they think 75% of other guests do so as well. This is a reason why some road signs indicate what percentage of the population drive at the recommended speed limit, and not how many drive over it.

  • How to Overcome This? If in doubt, try listening to your gut. If you are not sure if you are being swayed by the crowd, ask yourself ‘what would your opinion be if you didn’t know anyone else’s?’

    9 common thinking biases and how to overcome them infographic

The Dunning Kruger Effect: This thinking bias is potentially the most frustrating of them all. It describes how unskilled people tend to overestimate their ability, whereas experts doubt themselves. Researchers David Dunning and Justin Kruger were inspired by the story of an inept bank robber who believed the covering his face in lemon juice would make him invisible to the banks CCTV cameras.

Their subsequent study found that those who score in the lower bracket for their ability to tell funny jokes, use of grammar and ability to think logically consistently rated themselves in a much higher category.

  • How to Overcome This? Take anyone who makes definitive 100% statements with a pinch of salt. Experts are often comfortable talking about what they don’t know or the limitations of their work.

Find out more about the Dunning-Kruger Effect in this installment of our studies that every teacher needs to know.


The Ikea Effect – so named after the Swedish department store, which requires you to spend hours (often far more then you were hoping for) on assembling your flat-pack furniture. People tend to place a disproportionately high value on the things they personally create. In reality, this means that if someone has an idea, and has worked on it, they are more likely to cling to the notion that it therefore must be a good idea.

  • How to Overcome This? Just because it’s your idea doesn’t make it a good one. Know when to cut your losses and move on.

Outcome Bias – People often judge the quality of decisions based on the eventual outcome. This is common in sport; if people win then their decisions were good, but if they lose then the decision must have been bad.  Instead of judging your decisions based on the outcome, it is better to judge them based on the information you had at the time.  This is because the outcome can be random and based on a million different variables (many of which you have little to no control over).

  • How to Overcome This? Take time to reflect on what information you had at the time and if you would do anything differently next time.

The Planning Fallacy – simply put, people tend to under-estimate how long it will take them to complete a task. One classic study found that on average, students guessed that it would take them about 34 days to finish their final research project. The reality? The average time it took students to complete it was just over 55 days. The Planning Fallacy is one of the possible reasons why so many of us tend to procrastinate.

  • How to Overcome This? Give yourself more time than you think. Start earlier.

Final Thought

Think none of these biases apply to you? Chances are you are suffering from the Bias Blind Spot, which refers to the belief that other people are more likely to have these biases. The good news is you now know what some of the most common biases are and how to overcome them.

To find out more about thinking patterns and metacognition, visit our guide page here.

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