Risk perception has been defined variously as perceived or subjective probability estimates of death, other judgments of probable harm or loss, psychological states such as fear or traumatic stress, beliefs about causal processes resulting in harm or loss—that is, mental models of hazardous processes, or attitudes toward the activity, event, product, or substance in question. Risk perception, in which risk is assessed subjectively, often without formal decomposition into probability and harm, is frequently treated as folk or lay risk assessment.

When elicited as subjective probability or frequency of mortality, risk perceptions can agree or disagree with actuarial information, where such exists, and can in some instances be validated or invalidated by science. Comparisons of lay and expert risk perceptions, together with research on the effects of risk communication, illustrate that expertise and information can have large effects on risk perceptions. Such comparisons have been used...