Ex-Brexit secretary David Davis may not have much mental flexibility Leon Neal - WPA Pool/Getty Images

The first big psychological study of Brexit voters has found that people who voted Leave in the 2016 UK referendum share many personality traits with Trump supporters in the US, and supporters of far-right political parties in Europe. In particular, they were far more likely to have an “authoritarian” personality.

Around a third of people in western societies have authoritarian personalities. This personality type is partly determined by genes, and features a strong desire for order, obedience, conformity, and cohesion within the “in-group” with which the person identifies. Authoritarian personality was the best predictor of support for Donald Trump in the 2016 US election.

The Online Privacy Foundation, a UK charitable research organisation, worked with US researchers to administer standardised psychological tests online to 11,225 British volunteers just before the referendum. They asked each person how they would vote, and measured personality traits, thinking styles and susceptibility to bias.


“On the direct test for authoritarianism, Leave voters’ scores were nearly twice those of Remainers,” says team member Chris Sumner. “Leavers also scored significantly higher on conscientiousness and lower on openness, the personality traits most frequently associated with authoritarianism.”

Authoritarians’ concern for their in-group can lead to hostility towards immigrants, minorities or foreigners. Erik Tillman of DePaul University in Chicago has found such people tend to dislike the EU, and are more likely to join far-right parties in Europe.

Younger voters

The results parallel findings in the US. “There may be a broader pattern throughout the West in which high authoritarians are drawn towards sides that appeal to their needs for security and social conformity,” says Tillman. “The Leave campaign slogan of ‘take back control’ was probably very resonant with authoritarians.”

Over a person’s lifetime, their degree of authoritarianism can shift. “Threatening circumstances can make less authoritarian people significantly more authoritarian,” says John Jost of New York University. Education, however, can increase openness, having the opposite effect, he says.

The study also found that Leave voters were, on average, less good at handling numerical information. Male Leavers were more likely to over-estimate their own competence at a task.

Remainers were more subject to negative emotions, and more likely to think things through rather than using fast, emotional judgement.

Younger voters regardless of voting intention were more numerate and less subject to bias than older ones. “There is talk of lowering the voting age,” says Sumner, “but there may also be an argument for a cut-off point for older voters.”

Rigid thinking

Leavers also showed less mental flexibility on a test where they had to shift between different rules for sorting cards. This supports the finding of a study published in April, in which Leor Zmigrod at Cambridge University also found more rigid thinking among Leavers.

People who are mentally flexible and can tolerate uncertainty better are more likely to support flexible immigration and national borders, says Zmigrod. These traits are also linked to the belief that the UK government ought to be flexible in its implementation of Brexit in light of the potential costs. That’s a marked contrast to the UK’s Brexit secretary David Davis, who resigned today, telling prime minister Theresa May that he believed the government’s current approach may “just lead to further demands for concessions” from the EU.

Although cognitive flexibility is partly genetic, it can also be learned, and this skill may change more readily than personality traits. Zmigrod says studies like these provide insights into the psychological roots of nationalism, which she hopes may help bridge political divides.

Political polarisation

However, such findings could also worsen divisions. The latest study found that both voting groups were equally likely to misinterpret information so that it would fit with their existing beliefs. Such ideologically motivated reasoning can drive political polarisation.

Targeting political messages online according to people’s biases could reinforce this process. “Marketers are already targeting messages, in politics and other areas of consumption, to specific personality types,” says Jost.

“This and other research shows different personality types have different political behaviour. If marketers can determine personality types online, they can potentially target messages more effectively and at large scale,” Sumner says. “We don’t yet as a society know how that works in practice, how much it can be abused or how it should be controlled.”

But it may not be the propaganda bonanza it seems. “I suspect these targeted messages would have limited effectiveness,” says Tillman. “The relationships between personality type and political behaviour are not fixed, but probabilistic. Even two authoritarians vary in how they would respond to a targeted ad.”

The real message of the research, he says, is that politicians of all stripes need to find messages to attract voters across a range of personality types. “The Leave campaign and the Republicans have done a better job of appealing to authoritarian voters. The challenge for rival parties is to understand why and respond to it.”