Within decision making, the certainty effect is used to describe the impact of certainty on the decision maker. People are drawn to certainty, giving higher preference to options that have high levels [Page 122]of certainty. An option with high certainty (close to 0% or 100%) is more appealing to people than a complex or ambiguous probability. This causes many decision makers to choose options that go against the expected utility of the problem. A reduction in probability has a greater impact on the decision maker if the initial outcome is certain. For example, a reduction in survivability from 100% to 90% would have a greater impact than a reduction in survivability from 70% to 60%.

The underlying reason for the certainty effect falls on a person's ...