Health Belief Model

Over the past four decades, the Health Belief Model (HBM) has been one of the most widely used [Page 383]psychosocial models that attempts to explain health behavior and compliance. Formulated initially in the 1950s to help explain why individuals failed to engage in prevention or early disease detection behaviors, the model was later extended to embrace illness and sick-role behaviors, as well as compliance with medical regimens.

The still-evolving HBM integrates elements of operant conditioning and Kurt Lewin's theory of goal setting in the level-of-aspiration situation. As B. F. Skinner wrote, operant-conditioning theory focuses on the hypothesis that the frequency of a behavior is determined by its consequences or reinforcements, whereas Lewin et al. (1944) hypothesized that behavior depends mainly upon two variables: (1) the value placed by an individual on a particular outcome and (2) the individual's estimate of the likelihood that a given action will trigger a desired outcome. The model was subsequently categorized as an “expectancy x value” theory, attempting to describe behavior or decision-making processes under conditions of uncertainty.

The HBM is based on value-expectancy concepts: the desire to avoid illness or get well (value) and the belief that a specific health action available to a person would prevent or ameliorate illness (expectation). The expectancy was further delineated in terms of the individual's estimate of personal susceptibility to and severity of an illness, and of the likelihood of being able to reduce that threat through personal action.

The HBM proposes that one's subjective state of readiness to take action and engage in healthrelated behaviors, relative to a particular health condition, is a function of several factors. An individual's beliefs or perceptions of his or her likelihood of susceptibility to an illness, and the perception of the probable severity level accompanying a particular illness, represent major model features. Consequences can be social and physical. A second factor is the perceived benefit of the action, in contrast to the perceived barriers. That is, individuals are thought to weigh an action's effectiveness in reducing a health threat against possible negative outcomes associated with that action. A third factor involves access to cues for action or triggers. Cues can be either internal (e.g., pain) or external (e. g., interpersonal interactions or mediated messages). Becker and Mainman also emphasized that the preceding three factors can be influenced by demographic factors such as gender, age, and ethnicity; psychosocial factors such as social class and personality; and structural factors such as knowledge levels about diseases and concomitant disease experiences. A detailed review of the evidence supports the inclusion of the various HBM components. A brief summary of supporting evidence follows.