Political ideology is the number one determinant of rude, offensive or hateful comments on social media, according to findings of a four-month project conducted by journalists from DW and other news organizations in four European countries.

Comments posted on right-wing and populist politicians’ Facebook and Twitter feeds generated the most offensive comments directed at elected officials from the center or the left. Moreover, prominent female politicians in France and Italy bore the brunt of most hurtful speech.

But the study also found hate speech was less prevalent than generally assumed, and that there is a good way to curb it: having leading politicians take the lead in toning it down.

These are the findings of a four-month project conducted by journalists in France, Germany, Italy and Switzerland. The project rated more than 40,000 comments posted on the Facebook and Twitter accounts of a random sample of 320 politicians from February 21 to March 21. It used a rating system based on one devised by Article 19, an NGO dedicated to free speech.

The study comes at a time when politics have become more polarizing and governments are searching for ways to dampen incendiary speech, often by passing laws forcing IT platforms to take down posts.

Read more: Germany implements new internet hate speech crackdown

Andrew Smith, a legal counsel for Article 19, said it’s hard for social media companies to encourage rational political discourse without suppressing views. His NGO worries that technical solutions like filters and algorithm tweaks could lead to unnecessary censorship.

“Focusing on the actions of political leaders themselves rather than the platforms is certainly the right direction,” he said.

Posts on right-wing and populist politicians’ feeds generated more offensive comments than those on the feeds of elected officials on the center or the left. Six percent of the posts on French and Italian politicians studied were harsh. A smaller percentage of objectionable remarks were directed at Swiss and German politicians — 4.8 and 4.5 percent respectively.

Center and left-leaning politicians are troll magnets

At the same time, offensive speech tended to personally attack mainstream elected officials. A small number of politicians in each of the countries studied received a proportionately high amount of hate. All were from center or left-leaning parties.

They included Beatrice Lorenzin (Popular Alternative) and Davide Mattiello (Partito Democratico) in Italy, Ulla Jelpke (Left party) in Germany and Aurore Berge (En Marche) and Eric Alauzet (Green Party) in France.

Germany’s Michael Brand (CDU) drew the ire of trolls after writing that he was “disgusted” that AfD parliamentarians visited officials in Syria after the Assad government used chemical weapons. A Facebook page called Friends of AfD shared the conservative politician’s post, adding “Leave a nice comment with Mr. Brand.”

In Italy, a mandatory vaccination law drew vitriol against two pro-vaccine legislators. Lorenzin was called “Bastarda bastarda bastarda” and told, “I will curse you as long as I have an ounce of breath.” The most offensive comment was, “Lorenzin and [Paolo] Alli: For having betrayed Italy and Italians [there is] only one solution: shooting [them].”

Disagreeing with politicians is necessary for democracy. Rational people discussing important topics of the day need a variety of viewpoints to reach compromises and pass strong legislation. Anger can be an appropriate emotion for an issue.

EU hate speech rules may be working

The data showed overwhelmingly that most political discourse with politicians is polite. Few examples of possible illegal hate speech were found, and researchers spotted examples of possible hate speech posts disappearing from Facebook.

This could mean that the European Union’s 2016 code of conduct countering illegal online speech is working. That is hard to assess though because the social media platforms are not transparent about what they take down.

However, the rules are ineffective in getting people to speak nicely with one another. And far-right politicians see efforts to temper their language as suppression.

Read more: Mark Zuckerberg faces EU Parliament over data scandal

Populists attract support by stirring up emotion and fear

Whether the politicians want to be steered to talking pretty is another question. Data shows that populists appear to tolerate poisonous posts and memes.

Not all populists pick fights, however. Natalie Ricki, of Switzerland’s SVP, kept her Twitter feed civil by posting both fun comments — such as a photo of her riding a train to parliament with a member of another party — along with more serious policy statements.

Politicians who posted fearful and emotional comments tended to receive more offensive comments directed at groups. Their messages sizzled with contempt toward immigrants, Muslims, feminists and mainstream media — all of it protected speech.

This was the case in more than 9 percent of the comments shared on the profiles of the right-leaning leaders hoping to govern Italy. Comments included “mercenary invaders of Soros” or the “immigrants who destroy Florence.”

In Germany, resentment of immigrants dominated social media. In France, sexist comments got top billing. Both anti-immigration rhetoric and sexism were prevalent in Italy. Comments to Maria Elena Boschi, for example, ranged from “You’re beautiful!” to “You’re a sick ‘ho.” In Switzerland, comments were especially nasty about African immigrants and “lefty plunderers.”

Intimidating users can hurt democracy because it can have a chilling effect as people stop discussing issues for fear of being attacked.

Article 19’s Smith noted that politicians could make an effort to promote — and be role models of — polite discourse.

“Over time perhaps there will be some correction, but I think that requires politicians to take a proactive role in how they treat the speech of others and how they initiate conversations,” he said.

Research by Dr. Rania Wazir, a data scientist in Vienna; Alison Langley for DW; Francesca Sironi for L’Espresso; Alexander Fanta, Marie Bröckling, Julian Pütz and Leo Thüer for netzpolitik.org; and Vincent Coquaz in Paris; Infographics by Per Sander