What makes something go viral online? A lot of work has highlighted the role of emotion: social media posts that express strong emotions — and particularly negative emotions — tend to spread further.
Now a study in PNAS has identified another factor which seems to have an even greater effect on how often posts are shared. Steve Rathje from the University of Cambridge and colleagues find that tweets and Facebook posts that contain more language referring to political opponents get more shares. These posts may be so popular, the team finds, because they appeal to feelings of anger and outrage towards the political out-group.
The first study looked at hundreds of thousands of tweets and Facebook posts made in the last few years by media outlets with either a liberal (e.g. The New York Times) or conservative (e.g. Fox News) outlook. The team were interested in how the language of the social media posts related to how often those posts were shared. Using existing dictionaries designed for text analysis research, they looked at how many negative and positive emotion words (e.g. “hate” or “happy”) each post contained, as well has how many “moral-emotional” words it had (these are words that are contained in both dictionaries of moral and emotional words, like “destroy”, “peace”, or “victim”).
The researchers also compared the text against “Republican” and “Democrat” dictionaries. These contained the names of politicians and political terms related to either party — so “Donald Trump” and “right-wing” were in the Republican dictionary, for example, while “Pete Buttigieg” and “leftist” were in the Democrat one.
The team found that posts were shared more often when they contained more negative emotion words: every additional negative emotion word was associated with a 5-8% increase in the number of times a post was shared (with the exception of Facebook posts by conservative media). Similarly, each additional positive word decreased the number of shares by 2-11%. Moral-emotional words had an even stronger effect, increasing the number of shares by 10-17%.
These findings are broadly consistent with past work finding that people tend to share negative and morally-laden posts online. However, the really interesting finding came from the analysis of political language. More “in-group” language (e.g. liberal media posts containing words from the Democrat dictionary) was generally related to more shares. But the biggest effect came from “out-group” language (e.g. liberal media posts containing words from the Republican dictionary): each additional out-group word boosted shares by a whopping 35-57%.
A second study took the same approach, but looked at posts by members of Congress instead. And the results were pretty much the same: negative and moral-emotion words were related to more shares, but this was eclipsed by the far bigger effect of out-group language. In this case, each additional out-group word increased shares by 65-180%. Looking at the results across both studies, the team conclude that, overall, each political out-group word increased shares by around 67% — several times larger than the effect of negative or moral-emotional words.
Posts about the political outgroup are presumably usually quite hostile, and this could be what drives engagement. The team found some indirect evidence that this was the case, by examining how the audience used Facebook’s reaction emojis. They found that posts with more political out-group language provoked more “angry” and “haha” reactions, suggesting that these posts tended to be designed to provoke anger or mockery. More in-group language, on the other hand, predicted more “love” reactions.
Overall, then, the results suggest that people tend to share social media posts which allow them to express their social or political identity — particularly those which disparage political opponents. This has implications for understanding why social media — and the political landscape more widely — has become so polarised, the authors write. For instance, we’re often concerned about social media becoming an “echo chamber”, where people only hear from others who they agree with. The study suggests the problem isn’t simply that people only hear from their in-group, but that the posts they are most likely to see may actively promote animosity towards the out-group.
Unfortunately, things may not change any time soon. There are benefits to going viral: politicians or media outlets might gain followers, while social media companies rely on audience engagement for revenue. So this kind of polarising content is actually being incentivised by the very structure of the social media platforms, the team writes. “Content expressing out-group animosity may be good at generating superficial engagement while ultimately harming individuals, political parties, or society in the long-term,” they conclude.