15 Cognitive Biases Which Influence The Way You Think

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When it comes to making a good decision, how well-informed are you?

Since the early 1960s, cognitive scientists and psychologists have been researching and sharing cognitive bias and give them each a name. How good are you at knowing some of the most well-known and can you spot these behaviours in yourself and others?

I’ve been blogging about cognitive dissonance over the last year or so as I have started to become familiar with online behaviours through social media. This has since informed my day-to-day thinking when working with others. I hope this post helps school leaders, as well as teachers, access how people think.

1. Groupthink

This is a psychological phenomenon that occurs within a group of people who seek conformity in an irrational or dysfunctional decision-making outcome. A perfect example is Ofsted’s desire to continue grading schools.

Ofsted leaders minimise conflict and reach a consensus decision without critical evaluation of alternative viewpoints, by actively suppressing dissenting views, and by isolating themselves from outside influences.

2. Belief Bias

This is when we base the strength of an argument on the believability or plausibility of the conclusion. An example:

“I didn’t quite follow why you wanted to ban mobile phones, but your conclusion seems about right.”

3. Courtesy Bias

Given an opinion that is viewed as more socially acceptable so as to avoid causing offence/controversy. An example:

“The last time we discussed exclusions, the conversation lasted for hours. Let’s move on.”

4. Anchoring Effect

This is when an individual relies too much on the initial piece of information offered when making decisions. An example:

“When we first surveyed teachers, this is what they wanted.”

5. Availability Heuristic

This is when an individual overestimates the importance of events given the greater availability of information. An example:

“I saw someone mention this on Twitter. We need to take it seriously!”

6. Bandwagon Effect

This is when an individual believes things based on the number of people who share the same belief. An example:

“The entire senior leadership team do not believe there is a problem with behaviour.”

7. Status Quo Bias

This is when the workforce prefers the current state of affairs over change. An example:

“If it isn’t broken, don’t fix it”,  says the most experienced teacher.

8. Gambler’s Fallacy

This is when a school believes that future probabilities are altered by past events, when in fact they are unchanged. An example:

“The photocopier broke three times last month. It’s unlikely it will happen again during the exam season.”

9. Ostrich Effect

This is when an individual avoids negative financial information by pretending it doesn’t exist. An example:

When the Department for Education denies there is a school funding crisis, or your head teacher says: “We don’t have the budget to make XYZ happen.”

10. Illusion Of Validity

This is when a politician overestimates the importance and likelihood of events given the greater availability of information. An example:

When politicians deny that ‘selection increases the disadvantages for vulnerable pupils’ in exchange for ‘this is what parents want’.

11. Reactive Devaluation

This is when someone devalues an idea because it originated from adversary or opponent. An example:

“I wouldn’t read any of [his/her] ideas because they wouldn’t work in our school.”

12. Demotivating Effect

This is when a pupil or teacher receives retrospective awards for attendance or employee performance. What is actually does is lead to a [future] decrease in performance. An example:

“Congratulations to [Ross] for improving his attendance from 65% to 83% this academic year.” What then happens is, [Ross’] attendance drops in the future and the ‘original reward’ and its impact is not evaluated after it is received.

13. Pygmalion Effect

This is when the expectations teachers have of their students inevitably effects the way that teachers interact with them, which ultimately leads to changes in the student’s behaviour and attitude. An example:

“Mr. McGill, I want you to teach the bottom set this academic year.”

What this does is, it reinforces to Mr McGill that he is teaching a difficult class and frames his perceptions and expectations.

14. Bystanders Uncertainty

This is when something negative happens in front of a large group of people. If colleagues are gathered in groups, do we all ignore [a behaviour], or does one [from the group] take responsibility? Psychologists call this ‘bystander uncertainty’. An example:

There is a fight on the corridors and some teachers go in and intervene, putting themselves at risk. Other staff who see the incident, walk away, placing their colleagues at risk in return for an easier choice to avoid paperwork and threatening behaviour.

The recommendation is, that if one person delegates specific tasks to bystanders, this ensures other people participate rather than ignore. This would make a great addition to behaviour policies in schools.

15. Confirmation Bias

There are many other types of bias I could have chosen, but confirmation bias is vital for all teachers to know, particularly those using social media. This is when an individual focuses on information that only confirms their existing preconceptions. An example:

“We listened to what teachers said. Most of them said that there was no problem.”

Or an example, when a teacher presents an idea to a school leader: “I’d like to use virtual reality in my classroom.”

School leader: “Ooh, I’m not sure this will work well with our behaviour policy.”

When we tend to search for, interpret, focus on and remember information in a way that confirms one’s perceptions. This is an irrational decision to be able to estimate correctly what is happening.

There is an extensive list here and a great range of graphics available to help you get a good, initial understanding.



In 2010, Ross Morrison McGill founded @TeacherToolkit from a simple Twitter account through which he rapidly became the 'most followed teacher on social media in the UK'. In 2015, he was nominated as one of the '500 Most Influential People in Britain' by The Sunday Times as a result of being most influential in the field of education. He remains the only classroom teacher to feature to this day ... Sharing resources and ideas online as @TeacherToolkit, he has built this website (c2008) which has been described as one of the 'most influential blogs on education in the UK', winning the UK Blog Awards (2018). Read more...

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