Geology 140 - Environmental Geology
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Risk Notes

Experts and the public tend to evaluate risk differently. These are the results of a 1987 study by Paul Slovic that laid the groundwork for the modern study of risk perception.

When asked to evaluate the risk of 30 common activities, people cited these factors in explaining why they believed activities to be more risky than the statistical risk of death would indicate:

Dread Factor
“Knowability” factor
Not Observable
Not Dread
Unknown to Those Exposed
Known to those Exposed
Consequences Not Fatal
Consequences Fatal
Effect Delayed
Effect Immediate
Not Equitable
New Risk
Old Risk
Risk Unknown to Science
Risks Known to Science
Low Risk to Future Generations
High Risk to Future Generations
Example: Genetically engineered food
Example: Bees
Easily Reduced
Not Easily Reduced
Risk Decreasing
Risk Increasing
Example: X-rays
Example: Nuclear power

Source: Slovic, P., 1987, Perception of risk. Science, 236:280-285.

Risk & Social vulnerability

Vulnerability is a function of


Technology v. Social planning

Example of technological fixes:

Examples of social planning

If you have limited money to spend, where would you invest it?

More things that affect our perception of risk: