Risk perception, fuzzy representations and comparative optimism.

Rather than a unitary value, individuals may represent health risk as a fuzzy entity that permits them to make a number of specific possible estimates. Comparative optimism might be explained by people flexibly, using such a set to derive optimistic risk estimates. Student participants were asked to rate the likelihood of eight harmful alcohol-related outcomes occurring to themselves and to an average student. Participants made either unitary estimates or estimates representing the upper and lower bounds of a set denoting 'realistic probability' estimates. Personal risk estimates were lower when they were made as unitary estimates than those calculated from the mid-points of the bounded estimates. Unitary estimates of personal risk made after the bounded estimates were lower than initial unitary estimates. There were no effects for estimates made with regard to the average student. Risk may be internally represented as a fuzzy set, and comparative optimism may exist partly because this set allows people the opportunity to make optimistic unitary estimates for personal risk within what they see as realistic parameters.