THE EFFECT OF CATASTROPHE POTENTIAL ON THE INTERPRETATION OF NUMERICAL PROBABILITIES OF THE OCCURRENCE OF HAZARDS

Two studies demonstrated that identical numerical probabilities of the occurrence of hazards are judged as higher when these involve potenti al catastrophes compared to noncatastrophic hazards. Fifteen hazards w ere presented that involve a potential catastrophe and 15 noncatastrop hic hazards. Each hazard was given a numerical probability, which was either 1:10, 1:1,000, or 1:100,000. Numerical probabilities were rated as larger when these concerned hazards that have catastrophe potentia l compared to the noncatastrophic hazards, also when this effect was c ontrolled for perceived benefits. Similar results were obtained in a s econd study, which controlled for possible confounds (e.g., base rate) . The results suggest that verbal interpretations of numerical probabi lities of the occurrence of hazards include more than only probability , for instance one's attitude toward the hazardous activity. Implicati ons for risk communication are discussed.