The effect of catastrophe potential on the interpretation of numerical probabilities of the occurrence of hazards

Two studies with a total or 180 undergraduates demonstrated that identical numerical probabilities of the occurrence of hazards are judged as higher when these involve potential catastrophic compared with noncatastrophic hazards. In the 1st study, 153 Ss were presented with 15 catastrophic and 15 noncatastrophic hazards in a questionnaire. Each hazard was given a numerical probability of 1 in 10, 1 in 1,000, or 1 in 100,000. Ss were asked to judge how large or small the probability was that a hazard would occur on a response scale of very large to very small. Numerical probabilities were rated as larger when they concerned hazards with catastrophic potential. Controlling for perceived benefits did not change the effect of catastrophe potential on Ss' responses. A 2nd study with 27 Ss presented a catastrophic vs a noncatastrophic scenario with the same set of probabilities as study 1. This study, which controlled for possible confounds (e.g., base rate), showed similar results. Results suggest that verbal interpretations of numerical probabilities of the occurrence of hazards include more than the probability itself. (PsycINFO Database Record (c) 2007 APA, all rights reserved).