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Volume 3, Number 4—December 1997
THEME ISSUE
Foodborne

Identifying and Anticipating New Foodborne Microbial Hazards

Communicating Foodborne Disease Risk

Baruch FischhoffComments to Author  and Julie S. Downs
Author affiliations: Carnegie Mellon University, Pittsburgh, Pennsylvania, USA

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Thought processes involved in decision-making

People simplify. Many decisions require people to deal with more details than they can readily handle at any one time. To cope with the overload, people simplify. People want to know if foods are "safe," rather than treating safety as a continuous variable; they demand proof from scientists who can provide only tentative findings; and they divide the participants in risk disputes into good guys and bad guys. Such simplifications help people cope, yet also lead to predictable biases (7).
Once people's minds are made up, it's hard to change them. People are adept at maintaining faith in their beliefs unless confronted with overwhelming evidence to the contrary. One psychologic process that helps people to maintain their current beliefs is underestimating the need to seek contrary evidence. Another process is exploiting the uncertainty surrounding negative information to interpret it as consistent with existing beliefs (8).
People remember what they see. People are good at keeping track of events that come to their attention (9,10). As a result, if the appropriate facts reach people in a credible way before their minds are made up, their first impression is likely to be the correct one. Unfortunately, it is hard for people to gain firsthand knowledge of many risks, leaving them to decipher the incomplete reports they get.
People cannot readily detect omissions in the evidence they receive. It is unusual both to realize that one's observations may be biased and to undo the effects of such biases. Thus people's risk perceptions can be manipulated in the short run by selective presentations. People will not know and may not sense how much has been left out (11). What happens in the long run depends on whether the missing information is revealed by other experiences or sources.
People may disagree more about what "risk" is than about how large it is. One obstacle to determining what people know about specific risks is disagreement about the definition of "risk" (12-15). For some risk experts, the natural unit of risk is an increase in probability of death; for others, it is reduced life expectancy; for still others, it is the probability of death per unit of exposure. If lay people and risk managers use the term "risk" differently, they may agree on the facts of a hazard, but disagree about its riskiness.
How much does the public know and understand? The answer to this question depends on the risks consumers face and the opportunities they have to learn about them. The next section discusses strategies for improving those opportunities.

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