Getting Lost In The “Realm Of Possibility”: Common Phrases Used To Communicate Rare Events Have Substantially Different Effects On Decision-Making

Abstract

Communicating probabilities is challenging. Numbers are precise, but poorly understood by the public. Verbal phrases (“it is unlikely”) can be misinterpreted. The current study used a binary decision task (total n = 3207) to compare how varieties of verbal and numerical phrases impact decision-making. We identified “realm of possibility” phrases from real-world risk communications. These produced substantially higher risk perceptions compared to other formats. Verbally-formatted phrases increased risk perceptions compared to numerically-formatted ones. Contrary to previous findings, the “1-in-X” format did not uniformly increase risk perceptions compared to when percentages were used. When using the “1-in-X” format, risk perceptions decreased monotonically with the increased probability of negative decision outcomes. With percentages, risk perceptions instead showed a curvilinear (and contradictory) trend.