This blog post, provided by the IPR Behavioral Insights Research Center and written by Dr. Terry Flynn and Tim Li, is based on a research paper by Eric R. Stone, Ph.D., Emily C. Reeder, Ph.D., Jonathan Parillo, Cynthia Long, and LeeAnn Walb.
Key findings
- Risk perception of low-probability risks is more accurate when the number of people harmed and the number of people at risk are presented as a proportion and in the same modality, either as all text or all graphics.
Implications for Public Relations
Risk communicators can facilitate more accurate perceptions of low-probability risks by presenting them in a way that makes it easier to form proportions. This can be accomplished by presenting the number of people harmed in relation to the number of people at risk. It is also beneficial to present this proportion in the same medium, such as all text or all graphics. For example, textually this information can be shown as a fraction with the number of people harmed as the numerator, and number of people at risk as the denominator. In some cases, like in healthcare where risk aversion is desired even for low-probability risk, it may be better to use strategies to increase perceptions of risk instead. However, when it is potentially costly to overestimate a low-probability risk, proportional reasoning can be used to influence accurate evaluation of risk.
Summary
Low-probability risks are generally more difficult for people to understand. It is often important for risk communicators to convey that a risk is minimal, as people may overvalue reductions in already low-probability risks, resulting in poor and potentially costly decisions. Risk is typically presented as the number of people harmed out of the number of people at risk, e.g. 4 injuries in 1,000,000 incidents.
Stone and colleagues investigated how visual emphasis and graphical depictions influenced the perception of low-probability risks. They presented participants with various configurations of displays to present pairs of low-probability risks and had participants rate their perceptions of difference in risk and the value of a risk reduction. The conditions varied the presentation of the two components of risk (number of people harmed, and number of people at risk) by using bolder font and color or by using icons to create emphasis.
The results found that risk perception was reduced when both components of the information were presented in the same modality, either all as text or all as graphics. Placing both components of information in the same modality allowed participants to more easily form proportions. Presenting risk information in a way that makes proportionality easy to understand can lead to more accurate perceptions.
Blog post compiled by Dr. Terry Flynn and Tim Li.
Citation
Stone, Eric R., Reeder, Emily C., Parillo, Jonathan, Long, Cynthia, & Walb, LeeAnn. (2018). Salience versus proportional reasoning: Rethinking the mechanism behind graphical display effects. Journal of Behavioral Decision Making, 31(4), 473-486. https://doi.org/10.1002/bdm.2051
