The health belief model uses psychological indicators to predict health behaviors and conditions. The model assumes that a person's beliefs and attitudes about health behaviors influences their actions just as much as (and sometimes more than) thier knowledge of the consequences of these behaviors. The health belief models can help explain why people sometimes engage in high-risk health behaviors even though cognitively they understand the potential negative impact of those behaviors. An example is smoking. The health belief model takes from psychology the idea of exceptionalism. Exceptionalism is a psychological trap that many fall into: the idea that what happens to most people will not happen to you. A person suffering from cognitive illusion will continue to smoke, despite knowledge of statistics relating smoking to lung cancer, shorter lifespan and other quality of life issues. Subconsciously, the person may believe himself to be an exception to this rule. Thus, he may say things like: "I've been smoking for this long and it hasn't killed me yet," or: "My grandfather smoked and lived to be over 100."
The benefit of this model is that it helps us remember that people's health choices are based not only on rational thought but also on emotions, habits, social conditioning and personal preference. Thus, it opens our eyes to what might be more effective social teaching methods around healthy habits.
This model is limited to health-risk behaviors and as such can't help us understand the environmental, social and personal factors that influence health conditions. For example, belief may influence a person's decision to smoke, but it does not influence whether that person does develop lung cancer. The health belief model helps health care practitioners develop educational and social awareness programs that can change behavior, but does nothing to advance knowledge of how to treat various diseases or conditions once a person develops them.