Weather warning uncertainty: High severity influences judgment bias

Information about hurricanes changes as the storm approaches land. Additionally, people tend to think that severe events are more likely to occur even if the probability of that event occurring is the same as a less severe event. Thus, holding probability constant, this research tested the influence of severity on storm judgments in the context of updates about the approaching storm's severity. In two studies, participants watched one of four (experiment 1) or one of five (experiment 2) sequences of updating hurricane warnings. The position of category 1 and category 5 hurricane warnings in the sequences varied (e.g., category 1 first and category 5 last, or category 5 first and category 1 last). After the videos, participants made judgments about the approaching storm. In experiment 1, participants generally overestimated the threat of the storm if they saw a category 5 hurricane warning in any position. Experiment 2, designed to test whether experiment 1 results were due to a contrast effect, revealed a similar pattern to experiment 1. Overall, when participants saw a category 5 hurricane warning, they anchored to severity regardless of updates that the storm had decreased in severity. Importantly, however, the extent of anchoring to severity depended on the type of judgment participants made. In terms of policy, the study proposes that weather warning agencies focus on message content at least as much as they focus on message accuracy.