The researchers analysed the text of speeches delivered between 1950 and 2019 in Washington DC, London, Vienna, Amsterdam, Wellington in New Zealand, Copenhagen, Madrid, Bonn in Germany and Berlin, and linked temperature data on the day of the speech to the language used by lawmakers.
The analysis found that politicians’ language skills declined on hotter days but not on colder days, with heat-induced declines in language complexity scores equivalent to “roughly half a month’s decline in educational achievement.” Speeches delivered on hotter days had 3.3% shorter word lengths, although sentence lengths remained the same.
The researchers analyzed some of the German data and found that for lawmakers over the age of 57, the heat effect began at 69.8 to 75.2 degrees Fahrenheit. Men and women differed in language complexity during hot weather, but the differences were not statistically significant. The effect extended to indoor speeches as well, the researchers said, theorizing that this may be due to lawmakers’ brief exposure to outdoor heat on the way to a speech, noting that “extreme temperatures may also disrupt sleep.”
“Simplification of political discourse has complex implications: Simpler language may increase public understanding and engagement, but it may also signal reduced cognitive performance due to the heat,” Tobias Widman, an assistant professor of political science at Aarhus University in Denmark and co-author of the study, said in a news release. “This could have a negative impact on MPs’ productivity, affecting legislative decision-making, public representation and budget planning.”
The study did not examine the specific mechanisms behind the decline in linguistic complexity, and the researchers note that many political speeches are written long before they are actually delivered. They recommend that future studies include more sophisticated linguistic measures, as well as demographic data on speakers. But extreme temperatures “can have far-reaching adverse effects across society,” they write.
