Confirmation bias: What it is and how to avoid it

There are still thousands of posts from both sides of the ‘Brexit’ debate all over social media with completely different views on what’s happened so far, interpreting the results of the debate and, unfortunately, generally hurling abuse based on the ‘facts’ as they see them.

When you challenge the people that write them after investigating these claims they very quickly fall apart and you end up having a discussion that end something along the lines of “well it doesn’t matter I was wrong about ‘x’ specifically, my point still stands”.

So I thought I’d write a quick post on Confirmation Bias to explain what it is, why it really matters and how you can try to avoid it.

What is confirmation bias?


A great explanation from the talented Kris Straub at

Wikipedia describes confirmation bias as:
“…the tendency to search for, interpret, favor, and recall information in a way that confirms one’s preexisting beliefs or hypotheses, while giving disproportionately less consideration to alternative possibilities.”


What this means in practice is that you’re far more likely to interpret any facts from your point of view, read news sources that generally agree with your perspective or, at it’s worst, actively look for information from any source that confirms your views.

Confirmation bias has been in full force throughout the ‘Brexit’ debate and it hasn’t stopped after the results are in with posts from both sides supporters quoting their interpretation of the information available or quoting sources that have been proven to be false long afterwards.

Why does it matter?

Confirmation bias matters because is kills democratic debate as both sides instead of listening to each entrench themselves reading news sources, blogs etc. that agree with their view and dismissing any other viewpoints. This leads to poor choices and the polarisation of public opinion.

One of the best examples during the UK’s EU referendum was from the Leave campaign where after realising that they didn’t have the support of any of the major economists and global economic organisations supported them. The Leave campaign then very skillfully began to cast doubt on select experts credentials, accused anyone that opposed them of “being in the pocket” of the European Union and most effectively just accused the Remain campaign of being “negative”.

The accusation of being negative was incredibly effective and many supporters of the Leave campaign repeated the manta over and over making it impossible for the Remain campaign to communicate their points effectively.


The now infamous Vote Leave Campaign Bus with the discredited £50m a day quote that the Remain campaign failed to counteract effectively with Leave supporters.

Another great example of confirmation bias in action from the EU referendum is the Vote Leave campaign bus.

The Vote Leave campaign bus claim was that the UK send the EU £50 million a day, which could be better spent on the NHS, the UK’s treasured National Health Service, and implies that the UK needs to take control of it’s finances from the EU.

Both the amount quoted and the implication the UK doesn’t have control over it’s budgets to better fund the NHS that are emblazoned across the side of the bus are both very easily disproved with some quick research. Once you work out that much of the figure doesn’t exist you realise that there’s no way that by leaving the EU you could magically invest this extra money into the NHS.

So did the Vote Leave team change it….nope, they just criticised the Remain campaign of being negative and it worked, many voters expressed that the benefit to the NHS of the UK leaving the EU was a reason that they voted to Leave.

Of course when it came time to pay the piper when Vote Leave won it took less than twelve hours before Nigel Farrage appeared on Good Morning, a UK breakfast TV show in the UK, to explain that this was a “mistake”. It’s worth watching this clip to see that even after the win Nigel Farrage continues with the narrative that anyone that disagrees is just being negative and how he also changes the figure sent to the EU as £10bn.

So how can I avoid confirmation bias?

Confirmation bias is actually becoming increasingly difficult to avoid in the internet age because search engines like Google and Bing and social media sites like Twitter, YouTube and Facebook ‘tailor’ their results to show you the content that they think is most relevant to you based on your previous history on their sites.

The reason for this is that the longer they keep you engaged on their site the more opportunity there is to generate advertising revenue from you and you’re more likely to consume media if it agrees with you.

This means you actually have to actively look for opposing views, whether it’s from your friends, family or media outlets that don’t agree with your views and actually listen to their perspective allow your views to be challenged. That’s not to say that you’ll always be right or wrong but it’s incredibly important that you engage in debate, otherwise you’ll find that you’re constantly on one of the extremes of an argument and become blind to the actual facts.

Where to learn more

If you’re interested in understanding more about confirmation bias there are a huge number of sources available and I’ve listed a few that I’ve used and some great books on that cover confirmation bias to a greater or lesser extent below.

Confirmation Bias Articles

Some interesting articles about confirmation bias from around the web:

Interesting Reads

Some interesting books worth reading to learn more about confirmation bias, psychology and  why we make decisions the way we do. If you have other recommendations let me know and I’ll read them and add them to the list.

  • Thinking Fast and Slow – Daniel Kahneman
  • Freakonomics – Stephen J. Dubner and Steven D. Levitt
  • The Undercover Economist – Tim Harford
  • You Are Not So Smart – David Mcraney
  • Superforecasting: The Art and Science of Prediction – Philip Tetlock and Dan Gardner
  • The Confidence Game: The Psychology of the Con and Why We Fall for It Every – Maria Konnikova

What do you think?

If you have a different view or think I have it wrong please share your thoughts and let me know, I’m always interested in hearing other points of view and it’s only by working together we’re going to get through the next couple of years.



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