Expressions of uncertainty in online science communication hinder information diffusion.

Despite the importance of transparent communication of uncertainty surrounding scientific findings, there are concerns that communicating uncertainty might damage the public perception and dissemination of science. Yet, a lack of empirical research on the potential impact of uncertainty communication on the diffusion of scientific findings poses challenges in assessing such claims. We studied the effect of uncertainty in a field study and a controlled experiment. In Study 1, a natural language processing analysis of over 2 million social media (Twitter/X) messages about scientific findings revealed that more uncertain messages were shared less often. Study 2 replicated this pattern using an experimental design where participants were presented with large-language-model (LLM)-generated high- and low-uncertainty messages. These results underscore the role of uncertainty in the dissemination of scientific findings and inform the ongoing debates regarding the benefits and the risks of uncertainty in science communication.