My enemy’s enemy is not my friend: The psychology of polarisation in the Labour party

In just a matter of days, Labour is set to win the UK election by huge margins. Yet despite their massive lead in the polls, the party has never felt more divided. The culling of several key figures on the left of the party, such as Diane Abbot and Faiza Shaheen was intended to draw in more moderate and centrist voters. Yet it has also caused considerable backlash from progressives, many of whom are now turning to the Greens or refusing to vote at all.

These in-party factions are not driven by only one side. Corbyn’s supporters heckled Starmer in his inaugural conference speech, and he is regularly described as a ‘red Tory’ by more left-leaning voters.

Still, after 14 years of Tory government one might assume, that Labour supporters would be more willing to rally together against their opponents. However, new research from the University of Cambridge suggests that this may not be the case: Corbyn and Starmer supporters actually tend to prefer moderate Conservatives over each other.

The study of over 1,000 participants across the UK using an online survey, is the first to investigate the psychology of in-party polarisation. It found that people often hold more negative views of rival factions within their own party, than of members of the opposing party.

The most consistently observed in-group conflict was between the left and right of the Labour party, using support for Corbyn and Starmer as a proxy. However, divisions as strong as cross-party polarisation were also observed among Conservative voters.

Dr Lee de-Wit, a psychology lecturer at the University of Cambridge who oversaw the research, said, “to our astonishment, the effect size was huge…we expected to see some internal polarisation, but the fact that it would sometimes be larger than the polarisation between the parties is something we've not heard anyone theorise would happen.”

The project was conceived by Associate Psychology Researcher David Young, after he witnessed hostility online from Labour supporters towards Starmer, despite being 12 points ahead in the polls.

Using a typical measure of affective-polarisation, participants with established partisan affiliations ranked how much they liked their own and various other political groups. The results suggest party identity may be a less important factor in stoking political divisions than originally thought.

“It looks from our data like Corbyn and Starmer supporters now dislike each other as much as leave and remain voters do,” said Young.

While Starmer is almost certain to have a landslide victory, the research may stil have important implications for his election campaign as he struggles to unite Labour supporters. The research also suggests that people are less likely to vote for their affiliated party if the leader is from a different faction.

Dr de-Wit believes the data shows that the popular understanding of polarisation as “groupist tribal psychology triggering in-group preference and out-group dislike” is an “oversimplification”.

“If you follow that logic you're going to always like your side and hate the other.”

Young suggests the findings may be caused by competition for limited resources, as rival factions within parties are “in conflict over the positions of power within the party, the ability to influence the party which is a proxy for influencing government, they’re in conflict for finances, to get funding from donors, media influence, and for the affections of the electorate.”

He added, “the fact that there's another party you’re also in competition with doesn't mean that these disputes within your own side won’t produce hostility.”

Divisions around prevalent issues like Gaza are likely to have particularly fuelled polarisation in the Labour Party. A 2022 study from the University of Tennessee found that cultural issues are much more emotionally polarising than economic ones, due to being closely linked to our identity, values and morality.

Professor Kesi Mahendran, a professor of social psychology at the Open University, believes that the findings may reflect natural variance within each party rather than evidence of a process of polarisation. “Parties are a broad church and there’s continuity across the left-right spectrum…the centrists within both parties overlap each other,” she said.

She also believes the study may have missed a critical segment of the British electorate by only including participants who identified with one party, saying “the study immediately starts with a bipartisan framing, but the number of floating voters in the UK is very high.”

Still, she praised the work for looking beyond typical research. “The very fact that they've started to work within the ‘in-group’ is a positive step,” she said.

Since completing the first study, the team have now gathered around three times as much data in ongoing research with MHP Group's UK Polarization Tracker. Young explained that the new data revealed that even as Labour has become hugely more successful in recent months, hostility between the left and right of the party “has persisted.” As such, even if Starmer wins the next election, ongoing internal division may undermine Labour’s ability to run an effective government.