Examining Insensitivity to Probability in Evidence-Based Communication of Relative Risks: The Role of Affect and Communication Format

Abstract

Affect can influence judgments of event riskiness and use of risk-related information. Two studies (Ns: 85 and 100) examined the insensitivity-to-probability effect—where people discount probability information when scenarios are affect-rich—applying it to evidence-informed risk communication. We additionally investigated whether this effect is moderated by format, based on predictions from the evaluability and pattern-recognition literatures, suggesting that graphical formats may attenuate insensitivity to probability. Participants completed a prior beliefs questionnaire (Study 1), and risk perception booklet (both studies) that presented identical statistical information about the relative risks associated with two scenarios—one with an affect-rich outcome, the other an affect-poorer outcome. In Study 1, this was presented graphically. In Study 2, information was presented in one of three formats: written, tabular, or graphical. Participants provided their perceptions of the risk for each scenario at a range of risk-levels. The affect-rich scenario was perceived as higher in risk, and, importantly, despite presenting identical relative risk information in both scenarios, was associated with a reduced sensitivity to probability information (both studies). These differences were predicted by participants’ prior beliefs concerning the scenario events (Study 1) and were larger for the single-item written format than graphical format (Study 2). The findings illustrate that insensitivity to probability information can occur in evidence-informed risk communications and highlight how communication format can moderate this effect. This interplay between affect and format therefore reflects an important consideration for information designers and researchers.