This glossary collects the key concepts, people, and ideas you will meet in this lesson. Use it as a reference while you work through the material, or as a review before assessments. Type in the search box to filter entries.

No person is an island

Lesson 2 asked what a theory is and where behavioural theory came from. This lesson is the first to take up specific theories, and it begins with the theories that treat the individual as the primary source of behaviour: the Health Belief Model, the Theory of Reasoned Action and its revision, the Theory of Planned Behavior, the Transtheoretical Model, and the Precaution Adoption Process Model. Before introducing any of them, this lesson pauses on a question that sounds too obvious to ask. What is an individual? This section takes that pause seriously, because the answer shapes how every theory in the lesson should be read.

Back to the roommate

Begin by conceding the obvious. Of course individuals generate their own behaviour; we are not robots. Then return to the roommate from Lesson 1, Sam, brushing his teeth with unusual care. Sam was certainly making decisions and acting as an individual. But the information he used to make those decisions, the situation that was motivating him, and the parts of his family upbringing that shaped his toothbrushing habit all involved connections with a social world. The same holds for the theories in this lesson. They focus on the thought processes individuals go through before taking a health-related action, and that focus is legitimate. The task is simply to remember the context while you study them. The decisions people make to take or not take an action are based on cues, references, and information from their social, physical, and cultural environments. No person, as John Donne wrote in 1624, is an island.

The diagram shows the shape of every theory in this lesson. The box in the middle is where the theory does its work: it names the beliefs, attitudes, intentions, or stages that come before an action. The arrows from the left are what the theories mostly take for granted. They supply the raw material of a decision without being part of the model, and the critiques you will read in later sections nearly all turn on that arrangement.

What is an individual?

The best way to answer the question is to take the everyday answer apart. An individual, you might say, is an autonomous self with a distinct body, a personality, a way of talking and walking, goals, motivations, and the ability to plan and carry out action. You. Now examine each piece. Your body is genetic; it came from parents and ancestors, so it is you and also, in part, them. Your personality may have genetic influences, but your way of talking, walking, and dressing was assembled from pieces you did not invent. Compare this to a musician praised as a unique saxophone player, who is unique in the way he combines riffs he learned from others. Work through the pieces below and trace each one to its source.

The exercise does not make individuals disappear. You take these influences, shape them, and inhabit them as your own life. What it shows is that the process connects you to your world in ways that complicate any simple description of individual behaviour and motivation. When a theory in this lesson says that a person weighs benefits against barriers, ask where that person's sense of what counts as a benefit came from.

Two ways of drawing the line

There is great variety across cultures in how the idea of the individual is conceptualized, a point developed by the anthropologist Louis Dumont. Dumont distinguished societies that are said to be constructed of individuals, where the individual is the key, autonomous unit, from societies that are understood as the source from which individuals come, where society is viewed as more important than the individual. The distinction matters for this lesson because the theories you are about to study were written in the first kind of society and carry its assumptions. Use the tabs to compare the two views and to see why the difference is practical rather than philosophical for a health promoter in Canada.

What the individual theories assume

Reading across the five, the individual theories share three assumptions. First, behaviour follows a thought process: something happens inside the person before the action, and that something can be described and measured. Second, the process is largely rational and cognitive. People assess risk, weigh benefits against costs, form intentions, and move through stages; later sections will note that emotion, habit, and gut instinct fit awkwardly. Third, the person is both the unit of analysis and the unit of intervention. A program built on these theories changes what a person believes, intends, or is ready for, and expects behaviour to follow.

The five theories sort into two families, and the table previews them. The first family describes a decision that occurs as a single process at a point in time. The second describes change that takes place in stages over time, and treats the point-in-time theories as descriptions of what happens within particular stages.

A first case, before any theory

Keep Priya in mind. Each of the next three sections will pick her decision up again with a different theory, and the differences in what each theory notices are the content of this lesson. For every theory you will see the same four things: where it came from and who built it, the constructs it uses and how each is defined, how a program puts those constructs to work, and the critiques raised against it. You will also meet, in the next section, a name for what goes wrong when a program is built from a theory's constructs without first studying the people it is meant to serve. The warning applies to all five theories, and this lesson repeats it for each.

A screening program nobody used

The Health Belief Model comes first for two reasons: it is the oldest of the individual behavioural theories used in public health, and one of the most widely used. It also began with a practical puzzle, which makes its origin a good first lesson in how a theory gets built.

Origins: free x-rays and empty clinics

In the 1950s the United States Public Health Service sponsored free tuberculosis screening by x-ray in mobile clinics placed right in neighbourhoods. Free, convenient, and for a feared disease: attendance should have been high. Very few people came. Godfrey Hochbaum, a social psychologist with the Service, set out to learn why turnout was so low given the easy access, and the larger issue he investigated was motivation. His initial conclusions were that people were most likely to get an x-ray if they thought they were susceptible to tuberculosis and if they believed there was a benefit in early detection. That pairing was the nucleus of the theory. Hochbaum, Irwin Rosenstock, and Stephen Kegels developed it into the Health Belief Model (Rosenstock, 1974).

In its early formulation the model held that health behaviour was motivated by four factors: perceived susceptibility, perceived severity, perceived benefits of an action, and perceived barriers to taking it. As the model was applied to treatment adherence, prevention, and screening, two components were added. The first was the idea that cues to action were needed as direct motivation to act. In 1988, the influence of what was then called Social Learning Theory led to the sixth: a person's belief in their own ability to take the action, commonly referred to as self-efficacy. You will meet the source of that idea, Albert Bandura, in the next lesson.

Six constructs, one statement

Read the six components as parts of a single theoretical statement about a person we will call Jane. Jane will engage in a preventive behaviour given that she thinks she is susceptible to the health problem; she thinks the problem is severe; she thinks taking the action will do some good; she thinks there is not a lot standing in the way; something gives her a push to act; and she believes she is capable of acting. The cards give each construct with its definition and an example.

Finally, the Health Belief Model is described as a value expectancy model: people will engage in healthy behaviour if they value the outcome related to the behaviour, being healthy, and if they think the behaviour is likely to result in that outcome. Both halves matter. A person who values health but doubts that a screening test will change anything, or who trusts the test but does not much value what it protects, is predicted to stay home.

Return to Priya at the pharmacy door. The model would ask whether she feels susceptible to influenza (young and healthy, so perhaps not), whether she thinks it severe (for her grandmother, yes), whether she believes the vaccine helps, what she counts as barriers (a week in bed, her midterm), what cue is acting on her (the sign, her mother's remark), and whether she feels able to walk in. It has to be told which of these is loudest for Priya.

Using the model: the EZ program structure illusion

To use the model in a program, think of the six constructs as levers. They provide guidance, but they cannot be used as is, and a worked example that this lesson returns to in every section shows why. Suppose you want a group of serious urban blues musicians who are heavy smokers to quit, and you build a cessation campaign straight from the six constructs. Brochures carry clear information on the risks and severity of lung and throat cancer, with graphic pictures: susceptibility and severity covered. Flyers, text messages, and radio spots advertise inexpensive or insured quit programs promising a smoke-free client in a month, with testimonials from happy ex-smokers: barriers and benefits covered. A famous musician has died of cancer, and his widow's words go up in the clubs: a cue to action. A booklet titled One, Two, Three, Quit and free demonstrations by trained quit coaches: self-efficacy.

Three months later, not one musician has quit or even tried, the materials have been tossed, and barely a handful came to the demonstrations. The diagnosis is that you succumbed to what we can call the EZ program structure illusion. A theory is presented in the abstract. Its constructs need to be shaped by real-world information before you can use them or know whether they are effective. The cure is to do some research and target the program, and the theory, to the people you are trying to help, and to treat the theory as a tool, a guideline, and a framework rather than as the complete story.

So you do the research. Interviews reveal that hardly any of the musicians have insurance, and that a regular gig is so precious that losing a month of playing time could set someone back for many months with the club owners who pay them and the audiences who come to hear them. Time in the clubs shows that smoking is a social ritual, part of how musicians talk, play, and present themselves. Your pamphlets had advertised the risk of participating in a quit program rather than the risk of smoking. The table compares the two versions.

Practise the first step yourself. The builder mixes components from the musicians' campaign with components from a Canadian screening program. Assign each to the construct it is meant to move and read the feedback, which also says where the assignment is only a beginning.

Programs that used the model

A well-documented example is a mammography screening intervention in Baltimore, Maryland, where outreach had failed to engage low-income African American women. A culturally targeted intervention based on the Health Belief Model promoted a no-cost mammography program and collected data from women aged 40 and older on their screening history and their knowledge and beliefs about breast cancer. A 50 percent screening rate was achieved among 119 eligible participants, which the authors describe as unprecedented for that population, and the significant predictors of screening were perceived barriers, lack of insurance, and limited knowledge. Notice which constructs did the work: barriers, and a structural fact, insurance, that the model files under barriers.

Things to think about: critiques

No theory is without its critique, and the longest-running health behaviour theory has its share. Open each item.

The advice is to use theory as appropriate and keep a critical eye on the match between the theory and what you see: find out which constructs matter for these people before building materials, remember that a barrier may be a fact about the world that no message can change, and measure the constructs you claim to be moving, so that a program that fails teaches you why.

From attitude to intention to action

The second individual theory comes in two versions. The initial version, the Theory of Reasoned Action (TRA), was supplanted by a revised version, the Theory of Planned Behavior (TPB). The revision addressed a key critique of the original, but both are versions of one overall theory, often written as TRA/TPB. Like the Health Belief Model, it assumes a rational, cognitive decision-making process. Unlike it, the theory is organized around a question social psychologists had struggled with for decades.

Do attitudes predict behaviour?

Think about the gap between an attitude you have expressed and what you actually do. If you agree on a survey that honesty is the best policy, will you be honest in every circumstance? Probably not. If a robber asks how much money you have, honesty may not seem the best policy; nor will it if the truth would hurt someone. The issue is predictability. Do attitudes predict behaviour, and in what ways? This is the problem Martin Fishbein took up in the late 1960s, and then, with Icek Ajzen, addressed through the TRA and later the TPB (Ajzen, 1991).

After reviewing previous research, Ajzen and Fishbein concluded that the general construct of attitudes had to be separated from what they called behavioural intentions. There may not always be a link between attitudes and behaviour. But looked at more carefully, people move from general attitudes to attitudes about specific behaviours, and to assessments of how others view the behaviour, before they act. These stages culminate in an intention, and intention, according to the theory, is much more predictive of behaviour than attitude alone.

The Theory of Reasoned Action

In the original formulation, a behavioural intention follows from two things: a person's attitude toward a specific behaviour, and their perception of the subjective norms associated with it. Subjective norms are perceptions about whether the behaviour would be approved or disapproved by the social groups that influence the person. In this respect the theory does a little better than the Health Belief Model at accounting for social context.

An illustration adapted from Montano and Kasprzyk brings back Jane. Jane may have a fearful attitude about breast cancer as a disease. That attitude does not predict what she will do to prevent it, such as getting a mammogram. For that you have to look at her attitude about the mammogram itself and the social consequences she expects. Jane fears breast cancer but is skeptical about the overuse of expensive medical testing, and she believes her equally skeptical friends might ostracize her if she got one. The result is a low behavioural intention, despite her concern about the disease.

Each construct is built from two parts. Attitude toward a behaviour results from a belief about what will happen if the person does it, combined with an assessment of whether that outcome is good or bad. Subjective norm results from beliefs about what people in the social group will think, combined with the person's motivation to conform. The second part matters: a person confident of the group's acceptance may not feel much need to take its norms into account.

The reformulation as the Theory of Planned Behavior

Not long after the TRA was tested in programs, a significant flaw was revealed. Someone could form an intention and still not be able to do the behaviour, because factors outside their cognitive process, and outside their control, prevented them. Suppose Jane has a favourable attitude toward the mammogram and will not be swayed by her friends. She also works on a small farm; the nearest clinic is hours away by bus because her car is not running; and if she leaves for a few hours, tasks will go undone that could cost her the milk shipment. She intends to go and does not feel that she can. Intention alone is not a sufficient predictor.

The element added to address such situations is perceived behavioural control: the degree to which someone believes they have control over whether they can take the action, and the strength of that belief. It is separated into two parts. Control beliefs are beliefs about factors that will make the behaviour easy or difficult; if Jane thinks it would be easy to get a ride, that is a facilitating control belief, and if not, a constraining one. Perceived power is the power of those control beliefs; if a ride is the only possible way to the facility, her belief about the ride carries a great deal of weight. The labels are confusing, so here is a commonsense summary. If Jane has a positive attitude toward the mammogram, if her friends approve or she does not much care what they think, and if she thinks she can get a ride or, failing that, take the bus or a bike, then the likelihood is high that she will go.

The tabs show each construct in two parts.

The calculator lets you set the three constructs and watch the intention they produce, then add two complications from the critiques: actual control, and the time between intention and action.

Using the theory

To use the theory in a program, again think of the constructs as levers that must be in place, and again remember that they are not sufficient in themselves; every term must be specified for the group in focus. Set out to help the blues musicians quit using the three constructs straight from the theory, and you are shooting in the dark. You do not know what norms influence a musician's intention to quit, which social group matters most, or what factors shape a musician's sense of control over quitting.

With the research from the previous section, a program takes shape. Brochures feed positive beliefs about the outcomes of quitting: better health, a stronger singing voice, and the stamina to withstand the road. Group sessions near the blues clubs work on the norms of fellow musicians, the key social group, so that a musician considering quitting can factor positive norms into their intention. And the program removes constraining factors: the union expands insurance coverage and musicians hear about it, and club owners promise never to drop a performer who takes time off to quit, in exchange for free advertising. Each component targets a construct, and each is built from what the interviews revealed.

One example of a program that used the theory is a school study of physical activity: 366 high school students, divided into intervention and control groups, with a 12-week intervention of posters and lectures. It improved attitudes toward physical activity, perceived behavioural control, intention, and self-reported behaviour, but was less effective in other respects. For Priya, the theory would look past her general worry about influenza to her attitude toward this shot (a week unwell against her grandmother's protection), the norm she perceives (friends against, mother mildly for), and her control (she is at the door, so high). Her decision turns on which reference group carries more weight.

Things to think about: critiques

Three critiques are commonly raised against the TRA and TPB. Open each.

Change that happens in stages, over time

This section discusses the Transtheoretical Model (TTM) and the Precaution Adoption Process Model (PAPM) together because they represent one basic approach, change occurring in stages over time. The other individual theories are point-in-time theories: they treat the attitudes, beliefs, and decision about a behaviour as a single process. Will Jane get a mammogram? If she feels susceptible, if the risk seems severe, if the barriers are low, she does it or she does not, and the theory is done. A number of researchers began to question that structure.

Many little decisions

James Prochaska and Carlo DiClemente studied change processes among people who were quitting smoking and found a dimension missing from other theories: change takes place in stages, over time (Prochaska and DiClemente, 1983). People do not go through one process of decision but many, each belonging to one part of a continuum of change. Consider Jane, whose car was not running in the last section, buying a new one over the course of a week. Open each day and notice the stage it represents.

Her decision was many processes. A note on vocabulary: neither the TTM nor the PAPM is a theory per se. They are descriptions of a process that incorporate various theories to explain movement through it. In this sense they are models.

The Transtheoretical Model

Prochaska and DiClemente reasoned that changing behaviour is often like the car scenario, and that at each stage something different is going on, so that different theories apply by stage. Where a person is aware of a problem and deciding about action, the Health Belief Model or the Theory of Planned Behavior may apply. Where the person does not know there is a problem, it first has to get on their agenda, and other theories describe becoming aware. Because describing change requires many theories, the model was called transtheoretical, or stages of change for short. The six stages are on the cards; a person may enter at any stage.

Through all six stages, processes of change move people from one stage to the next and serve as guides for interventions. Two from a long list will serve as examples. Environmental reevaluation is a cognitive process in which a person considers how their behaviour affects others: a mother who smokes hears about secondhand smoke and thinks of her children. Counter-conditioning is a learned stimulus-response process in which a substitute behaviour counters the impulse toward the old one, such as exercising instead of smoking. Try matching callers to stages below; the feedback also shows how the second model would sort them.

The Precaution Adoption Process Model

The PAPM applies the same idea to a general category of behaviour: taking a precaution against something, such as installing smoke detectors. Neil Weinstein and Peter Sandman developed it to understand people's willingness or unwillingness to test their homes for radon, a naturally occurring radioactive gas (Weinstein and Sandman, 1992). Like Prochaska and DiClemente, they found that existing theories did not adequately represent how people react to hazards. Drawing on the TTM, they defined stages somewhat differently, as the table shows.

As in the TTM, many processes move people between stages, and some involve beliefs about benefits and costs, social norms, and confidence or skills, the material of the nonstage theories. Weinstein and Sandman stress that the variables important at one stage are not necessarily those that matter at another. The PAPM also states explicitly that the stages occur in order, a stronger claim than the TTM makes, although order is inherent in the TTM as well.

Using stage models

Using stage models can be a little complex, because the aim is to move a target group from one stage to another, and that requires three things. First, assess what stage the group is in, with a measure that fits the behaviour, since the stages of smoking cessation look different from those of changing diet. People will differ in stage, so you may need more than one intervention or may focus on the subset at highest risk. Second, draw on the processes of change relevant to that stage; if most people are unaware, consciousness raising about the problem itself is appropriate. Third, have criteria for judging whether the group moved. As for every theory, research connects the abstract model to actual people.

Return one last time to the blues musicians and choose the PAPM, because it separates unaware from unengaged. Suppose surveys find that half the musicians know the cancer risks but are unengaged, and half are deciding about acting, between the TTM's contemplation and preparation. Two interventions are needed. For the first group the task is to make the issue matter: tie cancer risk to singing, career longevity, and getting an audience; reduce barriers through unions and club owners; and put materials where musicians congregate. Then measure engagement before and after. For the second group the task is to make action easy: quit groups at music stores, made up of musicians so that social pressure runs the other way. Then assess whether they moved to action.

Three program examples follow the same logic. A community-wide Imagine Action campaign enrolled volunteers in a six-week physical activity program, with one registration question to assess stage; afterwards, 62 percent of those who began in contemplation and 61 percent who began in preparation had become more active. A 14-week nutrition intervention for undergraduates, with 11 lessons sequenced to TTM stages and processes, reduced dietary fat intake and held the change at one year, most strongly for students who began in pre-action stages; students without the intervention did not sustain their reductions. And the home radon study confirmed that barriers change by stage: risk information moved undecided homeowners to decide to test, and a low-effort how-to-test intervention moved those who had decided to order a kit.

Priya, one last time. A stage model asks where she is rather than whether she will act. She began the autumn in precontemplation; the sign and her mother's remark moved her to contemplation, and at the door she is weighing a week of feeling unwell against her grandmother's heart. She needs the decisional balance to tip, and then an easy action: no appointment, and the pharmacy is on her way.

Things to think about: critiques

Bringing It All Together

This lesson covered the theories that treat the individual as the primary source of behaviour, and it opened by complicating that idea. Sam decided to brush his teeth, but the information, the situation, and the upbringing behind the decision were social; the everyday self comes apart into genes, examples, stories, and people we chose to emulate; and Dumont's distinction reminds us that the theories were written in a society that takes the autonomous individual for granted. The five approaches that followed share a shape. Each describes what happens inside a person before a health action, treats that process as largely rational, and treats the person as the unit of analysis and intervention. The cues, references, and information that feed the process come from social, physical, and cultural environments, and the theories mostly take them as given.

The Health Belief Model began with Hochbaum's question about a free tuberculosis screening program that few people used. Its six constructs, perceived susceptibility, severity, benefits, and barriers, cues to action, and self-efficacy, read as one statement about a person, and the model is a value expectancy model: people act when they value the outcome and expect the behaviour to produce it. The Theory of Reasoned Action and Planned Behavior began with a different question, whether attitudes predict behaviour, and answered it by separating attitudes from intentions: attitude toward a specific behaviour and subjective norms produce an intention, and the revision added perceived behavioural control for behaviours a person cannot fully control. The Transtheoretical Model and the Precaution Adoption Process Model replaced the single decision with a sequence of stages, from precontemplation or unawareness through action and maintenance, and argued that the theory and the intervention that apply depend on where a person is.

Two threads ran through all of it. The first is the EZ program structure illusion. The blues musicians' campaign hit every construct of the Health Belief Model and moved no one, because nobody had asked what severity and barriers meant to musicians without insurance whose livelihood depended on gigs; the same warning applied to the Theory of Planned Behavior, where the reference group must be discovered before norms can be addressed, and to the stage models, where stage must be assessed before a process of change can be chosen. The second thread is the critiques, which land on the same three assumptions each time: context can block a rational calculation, constructs are unclear and few studies test a whole theory, emotion and habit fit awkwardly, time between intention and action is ignored, and stages are neither linear nor easy to measure. None of this makes the theories useless. It makes them tools, guidelines, and frameworks that require research and judgment, which is the stance this course asks you to take toward every theory.

Final Knowledge Assessment

This assessment covers all material from this lesson. You must score 100% to complete the lesson. Review the feedback for any incorrect answers and try again.