The perception of dramatic risks: Biased media, but unbiased minds

In their famous study on risk judgments, Lichtenstein, Slovic, Fischhoff, Layman, and Combs (1978) concluded that people tend to overestimate the frequencies of dramatic causes of death (e.g., homicide, tornado) and underestimate the frequencies of nondramatic ones (e.g., diabetes, heart disease). Further, their analyses of newspapers indicated that dramatic risks are overrepresented in the media-suggesting that people's distorted risk perceptions might be driven by distortions in media coverage. Although these patterns were not evaluated statistically in the original analyses, the conclusions have become a staple in the social sciences. How reliable are they? And are they replicable? In a systematic literature search, I identified existing replications of Lichtenstein et al.'s investigation and submitted both the original data and the data from the replications to a Bayesian statistical analysis. All datasets indicated very strong evidence for an overrepresentation of dramatic risks and an underrepresentation of nondramatic risks in media coverage. However, a reliable overestimation (underestimation) of dramatic (nondramatic) risks in people's frequency judgments emerged only in Lichtenstein et al.'s dataset; it did not replicate in the other datasets. In fact, aggregated across all datasets, there was evidence for the absence of a differential distortion of dramatic and nondramatic causes of death in people's risk frequency judgments. Additional analyses suggest that when judging risk frequency, people rely on samples from their personal social networks rather than from the media. The results reveal a limited empirical basis for the common notion that distortions in people's risk judgments echo distortions in media coverage. They also suggest that processes of risk frequency judgments include a metacognitive mechanism that is sensitive to the source of mentally available samples.