Hostility has a trivial effect on persuasiveness of rebutting science denialism on social media

Polarised social media debates between science deniers and advocates for science frequently devolve into hostilities. We conducted four preregistered experiments (N = 3,226; U.S. Americans) to assess how hostility influences the impact of misinformation from science deniers and rebuttals from advocates in social media discussions about vaccination (Experiments 1–3) and genetically modified food (Experiment 4). Results revealed only trivial to small effects of hostility on the persuasiveness of discussants: most internal meta-analyses showed effects smaller than the smallest effect size of interest (SESOI: d = 0.2). Rebuttal mitigated misinformation’s impact on attitudes and intentions even if advocates used hostile language; not responding had negative effects. Misinformation was impactful even with a hostile tone. Hostility consistently reduced perceived competence of messages.