Tuesday, October 21, 2014: 4:45 PM

Brian J. Zikmund-Fisher, PhD, University of Michigan, Ann Arbor, MI, Heather Lacey, PhD, Bryant University, Smithfield, RI and Laura D. Scherer, PhD, University of Missouri, Columbia, MO
Purpose: There is widespread evidence that even very rare risks can nonetheless weigh heavily on decision making for at least some people in certain circumstances. We sought to create an individual difference measure to identify people who show greater emotional reactivity to the possibility of bad or good outcomes occurring when the probabilities of these outcomes are well defined.

Method: We developed 14 short scenarios in which people imagined facing a well-defined risk presented in 1-in-X format (e.g., a 1 in 10,000 risk of experiencing a stroke from a medication or a 1 in 10,000,000 chance of winning a lottery). Both probability and valence (positive / negative) varied across scenarios. Participants rated how worried or excited they would be about the possibility of being “the 1 person” who had the event happen. We recruited 2464 Mturk participants to complete both this and other scales to examine scale reliability, factor structure, and discriminant validity versus other measures. In addition, we assessed these questions’ ability to predict (as part of another study) attitudes regarding the potential risks associated with various degrees of maternal alcohol use in pregnancy.

Result: The overall scale (i.e., average ratings of worry and excitement) was highly reliable (Cronbach’s alpha=0.84) and its factor structure included a main scale factor, a valence factor, and a probability level (rare vs. common) factor. It was only modestly correlated with subjective numeracy (r=-0.19) and tolerance for medical ambiguity (r=0.17) and uncorrelated with optimism (r=0.03) and rational-experiential thinking (r=0.02). Furthermore, the scale showed predictive validity: participants scoring higher rated a pregnant mother taking a single sip of alcohol as more likely to have caused fetal harm (p<0.001). A 3 question reduced scale focused on rare negative events had good reliability (alpha=0.75) and equivalent predictive validity.

Conclusion: Certain people appear more emotionally reactive to the possibility that they might be the 1 person out of many who would experience rare risk events. This sensitivity has unique relevance for predicting medical decisions about risk, especially rare complications risks. The “Be the 1” items tested here appear to be a reliable way of identifying such people. Additional research is needed to further establish its validity and assess its usefulness in research about risky decision making (both medical and non-medical).