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Theories of public health


As a part of any planning model, it is necessary to attempt to classify and explain the multitude of factors which can, and do, influence human behavior. Current models/theories that help to explain human behavior, particularly as it relates to health education, can be classified on the basis of being directed at the level of: a) Individual (Intrapersonal); b) Interpersonal; or c) Community. Within these three categories, those models/theories that have tended to dominate in the health education field in the past 20-30 years will be briefly outlined.

Individual (Intrapersonal) Health Behavior Models/Theories

  1. Health Belief Model (Rosenstock, Becker, Kirscht, et al.) Wambua and evelyne , Runoh

The Health Belief Model (HBM) was one of the first models which adapted theories from the behavioral sciences to examine health problems. It is still one of the most widely recognized and used models in health behavior applications. This model was originally introduced by a group of psychologists in the 1950’s to help explain why people would or would not use available preventive services, such as chest x-rays for tuberculosis screening and immunizations for influenza. These researchers assumed that people feared diseases and that the health actions of people were motivated by the degree of fear (perceived threat) and the expected fear reduction of actions, as long as that possible reduction outweighed practical and psychological barriers to taking action (net benefits).

The HBM can be outlined using four constructs which represent the perceived threat and net benefits: 1) perceived susceptibility, a person’s opinion of the chances of getting a certain condition; 2) perceived severity, a person’s opinion of how serious this condition is; 3) perceived benefits, a person’s opinion of the effectiveness of some advised action to reduce the risk or seriousness of the impact; and 4) perceived barriers, a person’s opinion of the concrete and psychological costs of this advised action. (See Figure 1) Another concept is known as cues to action. These are events (internal or external) which can activate a person’s “readiness to act” and stimulate an observable behavior. Some examples of external strategies to activate “readiness” can be delivered in print with educational materials, through any electronic mass media or in one-to-one counseling. Another concept that has been added to HBM since 1988 in order to better meet the challenges of changing unhealthy habitual behaviors (such as being sedentary, smoking or overeating) is self-efficacy. Self-efficacy, a concept originally developed by Albert Bandura in social cognitive theory (social learning theory), is simply a person’s confidence in her/his ability to successfully perform an action.

Even though the HBM was originally developed to help explain certain health related behaviors, it has also helped to guide the search for “why” these behaviors occur and to identify points for possible change. Using this framework, change strategies can be designed as referred to earlier. The HBM has been used to help in developing messages that are likely to persuade an individual to make a healthy decision. Using the HBM, messages that are suitable to health education for such topics as hypertension, eating disorders, contraceptive use, or breast self-examination have been developed.

However, there are two main weaknesses which have been noted about the HBM. First, health beliefs compete with an individual’s other beliefs and attitudes (outside of those described in modifying factors in Figure 1) which can also influence behavior. Secondly, in decades of research in the social psychology of behavioral change, it has not been shown that belief formation always precedes behavioral change. In fact, the formation of a belief may actually follow a behavior change.

  1. Stages of Change Model or Transtheoretical Model (Prochaska and DiClemente) Joyce

The Stages of Change or Transtheoretical Model was initially published in 1979 by Prochaska. In the 1980’s Prochaska and DiClemente worked further on this model in outlining the stages of an individual’s readiness to change, or attempt to change, toward healthy behaviors. The Stages of Change Model evolved from research in smoking cessation and also the treatment of drug and alcohol addiction. More recently it has been applied to other health behaviors, such as dietary changes. Behavior change is viewed as a process, not an event, with individuals at various levels of motivation or “readiness” to change. Since people are at different points in this process, planned interventions should match their stage.

There are six stages that have been identified in the model: 1) Precontemplation – the person is unaware of the problem or has not thought seriously about change; 2) Contemplation – the person is seriously thinking about a change (in the near future); 3) Preparation – the person is planning to take action and is making final adjustments before changing behavior; 4) Action – the person implements some specific action plan to overtly modify behavior and surroundings; 5) Maintenance – the person continues with desirable actions (repeating the periodic recommended steps while struggling to prevent lapses and relapse; and 6) Termination – the person has zero temptation and the ability to resist relapse.

In relapse, the person reverts back to old behavior which can occur during either action or maintenance. This model is a circular, rather than a linear model. In fact, as seen in Figure 2, it is more of a spiral as the person may go through several cycles of contemplation, action, relapse (or recycle) before either reaching termination or exiting the system without becoming free of the addictive behavior. Prochaska has used a “revolving-door schema” to explain the sequence that people pass through in their efforts to become free from addictions. People do not go through the stages and graduate; they can enter and exit at any point and often recycle several times. Other studies indicate that individuals often go through these same changes whether they use self-help or self-management techniques, seek professional counseling or attend organized programs.

  1. Consumer Information Processing Model (Bettman, McGuire, et al.) Joyce

The Consumer Information Processing (CIP) Model developed out of the study of human problem solving and information processing. Information processing has been one of the dominant paradigms in social psychology for quite a while, even though CIP is still relatively new. This model was not developed specifically for health related behavior, but it has many useful applications in the area of health education. Information is a necessary tool in health education. However, just as knowledge is necessary but not sufficient for behavior change, information is necessary but not sufficient for knowledge. There are limits to any person’s information processing capacity. This is defined as the limitations upon individuals in the amount of information they can acquire, use and remember.

By understanding the key concepts and processes of CIP, health educators can examine why people use or fail to use health information, and then design informational strategies that have better chances for success. The search for information is the process of acquiring and evaluating information. This process is affected by the person’s motivation, attention and perception at that point in time. In general, consumers tend not to engage in extended information searches.

There are two central assumptions of CIP. First, individuals are limited to how much information they can process (the information processing capacity referred to earlier). Secondly, in order to increase the usability of information, individuals combine little pieces or bits of information into “chunks” and make decision rules or heuristics to make choices faster and more easily. These are the rules of thumb which are developed and used to help consumers select more easily among alternatives.

James Bettman created one of the best known models of CIP which is shown in Figure 3. It shows a cyclical process of information search, choice, use and learning, and feedback for future decision-making. There are several feedback loops throughout the model. The consumption and learning processes involve internal feedback based on the outcome of choices and their use in future decisions. Bettman’s version of this model has now been extended to consider that the information environment affects how easily people obtain, process and use information. This includes the amount, location, format, readability, and ability to process relevant information.

There are some basic CIP concepts that can be applied to health education. Before people will use health information, it must be: 1) available, 2) seen as useful and new, and 3) processable or in a friendly format. It is necessary to choose the most important and useful points to communicate (either verbally or in print) and place this information first and/or last in the presentation in order to be remembered best. The information should take little effort to obtain, draw the consumer’s attention, and be clear. Key ways to synthesize information (“rules of thumb”) that have meaning and appeal for the target population should be formulated. In the learning process, keep in mind that participants have probably made related choices before and are not necessarily starting from scratch. The information designed specifically for the target population must be placed conveniently for their use.

  1. Theory of Reasoned Action (Fishbein and Ajzen) Margaret

The Theory of Reasoned Action was designed to explain not just health behavior but all volitional behaviors. This theory is based on the assumption that most behaviors of social relevance are under volitional (willful) control. In addition, a person’s intention to perform (or not perform) the behavior is the immediate determinant of that behavior. The goal is to not only predict human behavior but also to understand it.

According to this theory, a person’s intention to perform a specific behavior is a function of two factors: 1) attitude (positive or negative) toward the behavior and 2) the influence of the social environment (general subjective norms) on the behavior. The attitude toward the behavior is determined by the person’s belief that a given outcome will occur if s(he) performs the behavior and by an evaluation of the outcome. The social or subjective norm is determined by a person’s normative belief about what important or “significant” others think s(he) should do and by the individual’s motivation to comply with those other people’s wishes or desires.

Attitudes are a function of beliefs in this theory. If a person believes that performing a given behavior will lead to on the whole positive outcomes, then s(he) will hold a favorable attitude toward performing that behavior. On the other hand, a person who believes that performing the behavior will lead to mostly negative outcomes will hold an unfavorable attitude. These beliefs that form the foundation of a person’s attitude toward the behavior are referred to as behavioral beliefs.

Subjective norms are also a function of beliefs. However, these are beliefs of a different kind. These are the person’s beliefs that certain individuals or groups think (s)he should or should not perform the behavior. If the person believes that most of these significant others think s(he) should perform the behavior, the social pressure to perform it will increase the more s(he) is motivated to comply with these others. If s(he) believes that most of this reference group is opposed to performing the behavior, her/his perception of the social pressure not to perform the behavior will increase along with her/his motivation to comply with these referents. The beliefs which underlie a person’s subjective norms are termed normative beliefs.