After the results of the 2016 US Presidential Election, the way Americans treat each other changed as a function of their party affiliation, according to a new study.

In a two-stage experimental study, by Celia Moore (Bocconi University) and colleagues, published in PLOS ONE, how Democrats and Republicans allocated resources to their political friends and foes before and after the election was explored. A first group of 280 adult Americans made allocation decisions to groups with varied political affiliations before the final primaries and national conventions of both parties (May 3-8, 2016), when Hillary Clinton seemed poised to become President, and a second group of the same size and characteristics made the same set of decisions in the week after the election and its surprising outcome.

As party affiliation is a salient part of our social identity, especially around elections, authors expected that the results were experienced as an ego shock both by Democrats (negatively) and Republicans (positively). In particular, Democrats experienced the results as a threat, which undermines self-esteem and boosts in-group favoritism and out-group hostility.

In the pre-election stage of the experiment, people were asked their political affiliation and, then had to share a small sum of money with a group of three components, whose political affiliation was known. The groups could be composed of three political friends, two friends and an opponent, or two opponents and a friend. While Democrats would allocate around half the money to the rest of the group, irrespectively of their political affiliation, Republicans would yield significantly less money (around 36 cents on a dollar) to groups with one or two Democrats than to Republicans-only groups (58 cents).

After the election, participants were asked not only their party affiliation, but also a series of questions that measured their emotional reaction to the electoral outcome, their self-esteem and the strength of identification to their political party. Democrats were higher than Republicans in hatred, hostility, anger, fear, paranoia and suspicion and lower in self-esteem, and showed a behavior more similar to Republicans’ before the election, allocating 56 cents on a dollar to homogeneous groups and only 38 cents to groups with two Republicans. Republicans’ in-group favoritism and out-group hostility, on the other side, markedly softened (47 cents to Republicans-only groups and 41 cents to groups with two Democrats).

Statistical analysis confirmed that the effect was mediated by the fall (for Democrats) or rise (for Republicans) in self-esteem and that it was stronger in individuals with a stronger party identification.

“As subsequent surveys confirm that America remains deeply divided months after the election, the effects we have measured might be longer lasting than anyone might have expected”, Prof. Moore said.