Optimistic Bias

Optimistic bias (also called unrealistic optimism) refers to the tendency for people to think that they are less likely to experience negative life events and more likely to experience positive life events than similar others. For example, many people report that their chances of contracting AIDS, getting divorced, and attempting suicide in the future are smaller than those of their peers. Conversely, they also report that their chances of maintaining good health, winning professional accolades, and prospering financially in the future are better than those of their peers. Optimistic bias is a prevalent phenomenon in personal risk perceptions. As such, it has important influence on how people respond to science and technology communication, which often contains information about health, physical, and environmental risks.

Optimistic bias can be measured either directly or indirectly. We can ask individuals to directly report whether they think their likelihood of experiencing a future event (for example, being struck by lightning) is below, equal to, or above that of the average person with similar characteristics (for example, other people your age and sex). Alternatively, we can ask two separate questions. The first question asks individuals to report their own likelihood of experiencing the event. The second question asks them to estimate the likelihood that other people like them would experience the same event. The difference between the two answers can then be taken as an indirect measure of optimistic bias.

Although optimistic bias is typically measured on the individual level, it is often difficult to tell whether any given individual is truly biased in her comparative risk judgment. Depending on her actual risk status, a college student may be either accurate or inaccurate in stating that her risk of being struck by lightning is lower than that of her peers. Actual risk, however, is often difficult to ascertain. For this reason, many researchers have suggested that optimistic bias is best determined on the group level. The rationale is simple: Not everybody can be better off than average. If members of a group are accurate in their comparative risk judgments, their below-average risk estimates and above-average risk estimates should cancel each other out, resulting in a group mean that shows no self–other difference. If the group mean is below average (that is, when most members of the group believe that their risk is lower than the group average), we know that the group as a whole is optimistically biased.

Optimistic bias exists in people's risk judgments in many different domains. It tends to be particularly strong with risks that are rare, unfamiliar, and controllable by personal action (for example, suicide). The tendency for optimistic bias also appears to be consistent across different ages and socioeconomic backgrounds. Why do people develop such unrealistic optimism in their risk judgments? A popular explanation is that people hold optimistic biases because they need to maintain a positive sense of self. People often engage in downward social comparisons with less fortunate others so that they can feel good about themselves. Perceiving oneself as being less susceptible to potential harms and more likely to experience good fortune than others—even at the expense of distorting reality—is just another form of the comparisons that people may perform to bolster their sense of self-worth.

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