An outbreak of "collective narcissism" was a key factor that led the British population to vote for Brexit, psychologists claim.
Researchers investigated the role of xenophobia - fear of foreigners - in the referendum that led 52% of voters to support Britain leaving the European Union.
They found that "predictors of prejudice" were strongly linked to a tendency to back Brexit and be happy with the referendum's outcome, regardless of age, gender or education.
In addition, an assessment of personality types showed that people who felt threatened by immigrants fell into three distinct groups.
Some were "authoritarian" or "socially dominant" while others were described as "collective narcissists".
Collective narcissists were individuals who believed Britain was so great it deserved privileged treatment, but its "true importance and value" was not recognised by other countries, said the scientists.
Lead researcher Dr Agnieszka Golec de Zavala, from Goldsmiths, University of London, said: "Collective narcissism is not a good attitude to have. We should study how this becomes a group norm and find ways of preventing it from happening and spreading ..
"From Brexit, Trump and support for Vladimir Putin in Russia to the nationalist, ultra- conservative government in Poland, studies from ours and other labs show that collective narcissism systematically predicts prejudice, aggression and a tendency to interpret innocent behaviours as provocation to the national group."
The team - including investigators from the UK, Poland and Portugal - conducted two online surveys involving a total of 506 participants.
Writing in the journal Frontiers in Psychology, they described "right wing authoritarianism", "social dominance orientation" and "collective narcissism" as "robust predictors of prejudice".
All were related to the Brexit vote and support for the referendum's outcome "via the perceived threat of immigrants".
The authors added: "This suggests that the Brexit vote was motivated by different concerns instigating prejudice ..
"Collective narcissism was an independent and at least equally strong (if not stronger) predictor of the perceived threat of immigrants and support for the referendum's outcome as the other robust psychological predictors of xenophobia: right wing authoritarianism and social dominance orientation."