Visual organization of icon arrays affects Bayesian reasoning and risk judgments

Icon arrays can help patients to understand statistical information such as their risk of having a disease given a diagnostic test result. Bayesian problems such as these are computationally challenging but can be solved via the simple ratio of Ʃ(disease|positive)/Ʃ(positive cases). We tested whether organizing an icon array to place the two sides of this ratio nearer each other (proximal condition) enhanced risk judgments compared with an organization separating them (distal condition). Organizing icons proximally improved Bayesian reasoning by 31%-43% across two experiments. Participants were more likely to use the simple ratio in the proximal condition, but they used a different, less accurate ratio to judge risk in the distal condition. Current guidelines for risk communication endorse icon arrays but do not provide detailed design instructions. The present research demonstrates the importance of array organization and, in particular, icon proximity for communicating risk and facilitating Bayesian reasoning.

© American Psychological Association, 2022. This paper is not the copy of record and may not exactly replicate the authoritative document published in the APA journal. The final article is available, upon publication, at: https://doi.org/10.1037/mac0000044