The effects of communicating uncertainty on public trust in facts and numbers

Anne Marthe van der Bles*, Sander van der Linden, Alexandra L J Freeman, David J Spiegelhalter

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

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Uncertainty is inherent to our knowledge about the state of the world yet often not communicated alongside scientific facts and numbers. In the “posttruth” era where facts are increasingly contested, a common assumption is that communicating uncertainty will reduce public trust. However, a lack of systematic research makes it difficult to evaluate such claims. We conducted five experiments—including one preregistered replication with a national sample and one field experiment on the BBC News website (total n = 5,780)—to examine whether communicating epistemic uncertainty about facts across different topics (e.g., global warming, immigration), formats (verbal vs. numeric), and magnitudes (high vs. low) influences public trust. Results show that whereas people do perceive greater uncertainty when it is communicated, we observed only a small decrease in trust in numbers and trustworthiness of the source, and mostly for verbal uncertainty communication. These results could help reassure all communicators of facts and science that they can be more open and transparent about the limits of human knowledge.
Original languageEnglish
Pages (from-to)7672-7683
Number of pages12
JournalProceedings of the National Academy of Science of the United States of America
Issue number14
Early online date23-Mar-2020
Publication statusPublished - 7-Apr-2020


  • communication
  • uncertainty
  • trust
  • posttruth
  • contested

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