24 November 2023

Are Brexit voters thick?


An academic study published this week found that people with ‘lower cognitive ability’ were more likely to vote Leave in the 2016 UK referendum on EU membership. This was, of course, seized upon by many Remainers as more evidence that Brexit was a ghastly mistake. But does this stack up, or it is just another example of ‘confirmation bias’?

To be clear, this study is a serious piece of work. It was written by two economists at the University of Bath, Dr Chris Dawson and Dr Paul L. Baker, and builds on a growing body of research in the field of voting behaviour. You can read the original paper here. (It is fairly easy to understand, even for a Leave voter like me.)

In short, the researchers analysed the responses from a long-established survey of UK households, ‘Understanding Society’. They focused on a sample of 3,183 couples which, among other things, allowed them to compare the voting behaviour of two people living in the same household.

The assessment of ‘cognitive ability’ was based on the results of some standard tests, covering memory, verbal fluency, and numerical reasoning. For example, respondents were asked to name as many animals as possible in a minute, or to work out the compound interest on a bank deposit.

The results showed a strong correlation between cognitive ability and how people voted in 2016. Put simply, people who did better on these cognitive tests were more likely to back staying in the EU. Indeed, around 73% of the people in the top 10% for cognitive ability voted Remain, compared to only 40% of those in the bottom 10%.

Another striking result was that, while most couples voted the same way, where there was a split it was usually the person with the lower cognitive score who voted Leave.

However, there are two important caveats. One is that the results were weaker (though still statistically significant) when other factors were taken into account, notably education, favoured news sources, and party-political affiliation. In the words of the paper ‘the introduction of these influential controls all serve to substantially lower the cognitive ability coefficients’.

The other caveat, as the paper also acknowledges, is that correlation does not prove causation. In other words, the study does not prove that being less intelligent makes you more likely to have backed Brexit.

That said, the authors do suggest a possible causal link. Their main hypothesis is that the outcome of the referendum was heavily influenced by fake news and misinformation, and that people with lower cognitive ability were less able to filter this out.

I’m not sure I buy that. It is true that there was plenty of misinformation from the Leave camp, including the infamous ‘£350 million for the NHS’ (debunked here by Full Fact), claims that Turkey was about to join the EU, and that leaving the EU would not affect our access to the Single Market. 

Nonetheless, there was plenty of misinformation from the other side as well, notably the Treasury’s dire warnings of an immediate recession if the UK voted to leave. Indeed, social media is still full of ridiculous claims about the harm done by Brexit. 

My own take is that this research might be picking up something else. People who voted Remain were perhaps influenced more by the narrow economic arguments – and perhaps understanding these does require a higher degree of ‘cognitive ability’. 

On the other hand, perhaps those who voted Leave were influenced more by what former Bank of England Governor Mervyn King called “the issues of identity and culture and politics”. This may be more about ‘gut feel’ than, say, numerical reasoning, but no less valid a reason to vote one way rather than another.

This brings me to the final point, which is ‘so what?’. Let’s accept that, on average, people who voted Leave score marginally less well on particular cognitive tests than those who voted Remain. Are we really going to say that their votes should carry less weight? 

If so, should this apply more generally? For example, if I have read them correctly, the detailed results of the paper also suggest that people with higher cognitive ability are marginally more likely to vote Conservative than Labour. Does that mean anything?

There are also limits to measuring ‘intelligence’, or competence more generally, on the basis of these tests. Some people may just not be as quick at recalling facts, or as good at mental maths.

Other studies have suggested that people from different ethnic groups perform differently on standard Western IQ tests – but let’s not even go there. This is a slippery slope.

The upshot is that this new research should be taken seriously, but also interpreted with great care (as the original authors do). It certainly does not mean that the 17.4 million people who voted for Brexit can be dismissed as idiots.

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Julian Jessop is an independent economist.

Columns are the author's own opinion and do not necessarily reflect the views of CapX.