Imagination and the Availability Heuristic

The current findings lend support to past research showing that imagining hypothetical future events may render those events subjectively more likely (Carroll, 1978; Gregory et al., 1982). In our study, subjects who actively constructed images of experiencing a disease with easy-to-imagine symptoms judged themselves as more likely to contract that disease than did any other group of subjects. The opposite occurred when the symptoms were difficult to imagine: subjects asked to construct those images judged their likelihood of contracting the disease lower than did the other groups. The authors interpret this contrast through the availability heuristic. People appear to use the ease or difficulty of constructing a scenario as a cue to its probability.

The use of the availability or unavailability of a scenario as an indication of probability is of course consistent with the general use of availability for estimates of frequency or likelihood. Because likely events are typically easy to retrieve, imagine, or explain, whereas unlikely events are difficult to retrieve, imagine, or explain, subjects take the ease of imaginability as an indicator of likelihood. The problem with such a simple decision rule is, of course, that ease of imaginability may not always be caused by or even related to likelihood. Things other than frequency or likelihood may affect the ease with which a scenario may be constructed. For example, particularly vivid and striking events may easily spring to mind, and it is their vividness that causes the ease of imaginability rather than the likelihood of occurrence. Nevertheless, this implies that vivid events will be overestimated in terms of likelihood, and recent evidence is certainly consistent with this idea (Kahneman & Tversky, 1972; Lichtenstein et al., 1978; Rothbart et al., 1978).

Imagining a future event can affect both a judgment about it and the behavior that follows. Whether the thinking involves predictions of future events (Sherman, 1980), explanations of hypothetical events (Ross et al., 1977; Sherman et al., 1983), or, as in the present study, imagination of future occurrences (Carroll, 1978; Gregory et al., 1982), such thoughts clearly alter later judgments and behavior. Cognitive rehearsal and planning have been used in clinical settings to change the behavior of impulsive children (Meichenbaum & Goodman, 1971), reduce the relapse rate among alcoholics (Marlatt, 1978), and decrease the rate of early termination of therapy (Sherman, 1982). In the realm of sport psychology, imagination and mental rehearsal of upcoming performance have been shown to enhance performance (Suinn, 1976).

Because the present study dealt with estimates of disease likelihood, it might have practical implications for the health behavior area in particular. One of the major problems in the health field has been in the area of medical compliance (DiMatteo & DiNicola, 1982; Haynes, Taylor, & Sackett, 1979). People are especially unwilling to comply with appropriate preventive regimens such as immunization shots (Masur, 1981). Health professionals have been giving increasing attention to social psychological theory and practice in the hope of increasing medical compliance (Sensenig & Cialdini, 1984). Perhaps one of the problems in this area is that the diseases involved or the medical consequences of noncompliance are difficult to imagine, and thus the likelihood of such consequences is judged as extremely low. Note, for example, the traditionally low compliance rates associated with such disorders as hypertension (Sackett & Snow, 1979), in which symptoms are difficult for sufferers to detect and, consequently, to imagine. This suggests that the health profession might increase patient compliance and preventative compliance by making vivid presentations of the medical problems and by describing symptoms and consequences, as well as effective countersteps (Leventhal, 1970; Rogers & Mewbom, 1976), in easy-to-imagine terms.