Hot topics in science communication: Aggressive language decreases trustworthiness and credibility in scientific debates.

Current scientific debates, such as on climate change, often involve emotional, hostile, and aggressive rhetorical styles. Those who read or listen to these kinds of scientific arguments have to decide whom they can trust and which information is credible. This study investigates how the language style (neutral vs aggressive) and the professional affiliation (scientist vs lobbyist) of a person arguing in a scientific debate influence his trustworthiness and the credibility of his information. In a 2 X 2 between-subject online experiment, participants watched a scientific debate. The results show that if the person was introduced as a lobbyist, he was perceived as less trustworthy. However, the person's professional affiliation did not affect the credibility of his information. If the person used an aggressive language style, he was perceived as less trustworthy. Furthermore, his information was perceived as less credible, and participants had the impression that they learned less from the scientific debate.