Probability versus Consequences in Public Perceptions of Tornado Risk

Weather forecasters often consider the probability and intensity of extreme weather events when communicating information and risk. For example, a 1% chance of a severe (EF-3) tornado may be less risky than a 10% chance of a moderate (EF-2) tornado. Or, a 2% chance of a devastating (EF-4) tornado may be more risky than a 90% chance of a light (EF-0) tornado. Probability neglect is the tendency to disregard information about the likelihood of an event occurring when making decisions under uncertainty. Disregarding probability information often leads to overweighting information about the consequences. As the example above illustrates, low probability events that have high consequences (e.g., EF4 tornados) are often viewed as more risky than high probability events with low consequences (e.g., EF1 tornados) – even though this may not be consistent with normative standards of expected utility. Using data from the Severe Weather and Society Survey, an annual national survey that is conducted by the Center for Risk and Crisis Management at the University of Oklahoma, we consider the role of probability and intensity on individuals’ riskiness ratings (i.e., No Risk – Extreme Risk) for tornado events. Specifically, participants are randomly assigned a probability and an intensity rating and are asked to evaluate the riskiness of that event. Discussion focuses on individual differences that amplify or attenuate probability neglect (e.g., numeracy), implications for risk communication policy, and future research.