The research was carried out by Martijn Schoonvelde (University College Dublin) and UvA researchers Anna Brosius, Gijs Schumacher and Bert Bakker.

The researchers found that politicians who hold culturally liberal views on topics such as immigration, the EU, abortion and euthanasia use more complex language than right-wing politicians. ‘What is striking is that we came across the same results across different countries, different speeches and different types of politicians’, says Schoonvelde. ‘For instance, our scores show that former culturally liberal British Prime Minister Gordon Brown delivered speeches that were markedly more complex than his successor, the culturally conservative David Cameron. We saw the same thing in Spain, where the language used by liberal Prime Minister José Zapatero was much more complex than that of his successor, the conservative Mariano Rajoy. There are also notable differences between countries. For example, the culturally liberal German politician Joschka Fischer and British liberal Nick Clegg score much higher for the complexity of their language use than the conservative Dutch politician Geert Wilders or his Swedish counterpart Jimmie Åkesson.’

Political dimensions

‘European politics are generally characterised by political competition along two dimensions: a sociocultural conservative-liberal dimension and an economic left-right dimension’, explains Brosius. ‘The former typically includes issues like European integration, immigration and the environment, and is the dimension in which we distinguish between cultural-left and cultural-right.’ 

Political parties’ economic views do not explain the differences in complexity – the researchers found no association between economic left-right ideology and the complexity of politicians’ language use.

Persuasive message

According to Schumacher, the big question is why there are such noticeable differences in language use between politicians. A possible explanation is that politicians adjust their language use to appeal to the preferences of their voters. Shorter and clearer sentences may appeal to conservative individuals because they have a higher need for closure and consequently prefer more certain statements. Compound sentences with multiple clauses are more likely to convey ambiguity and may therefore appeal more to liberals who are generally more open-minded and tolerant of ambiguity. Bakker adds, ‘it could also be that politicians strategically use simpler or more complex language to appeal to constituencies with distinct personality profiles and associated preferences for linguistic complexity’. ‘After all, a persuasive message needs to resonate with the personality of the receiver.’

Over 380,000 speeches

The researchers analysed 381,475 political speeches from 10 European countries, including the Netherlands, Germany, the United Kingdom, Spain and Sweden. The speeches, spanning several decades, included parliamentary speeches, party congress speeches and speeches from government leaders. The researchers calculated the complexity of each speech with the use of the so-called Flesch-Kincaid readability score. The ideology of a politician was measured on the basis of the ideological position of his or her party. The team then did statistical analyses.

Hot Politics Lab

The researchers’ study forms part of a larger interdisciplinary research group, the Hot Politics Lab (www.hotpolitics.eu), which combines experiments, physiological measurement and automated text analysis to analyse the role of emotions, personality and language in politics.

Publication details

Martijn Schoonvelde, Anna Brosius, Gijs Schumacher & Bert Bakker: ‘Liberals Lecture, Conservatives Communicate: Analyzing Complexity and Ideology in 381.609 Political Speeches’, in: PLoS One (6 February 2019). E0208450.