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.

Why start with a toothbrush?

Any serious discussion of health behaviour involves wrestling with abstractions: motives, causal and contributing factors, contexts, cues. This lesson avoids starting there. It starts with a friend brushing his teeth, and it uses that scene to show that even the most ordinary health behaviour can have several explanations at once. This section works through the scenario, the questions it raises, and the first hints that where a person lives, what they can afford, and what the law allows often matter more than what they want.

Sam and the toothbrush

Suppose a friend, Sam, is brushing his teeth very vigorously. You ask why. He is puzzled by the question: he does not want cavities, and he does not want his teeth to fall out. End of story. Sam brushes to maintain healthy teeth, and that makes perfect sense.

Toothbrushing is a good example precisely because it is habit, far below the radar of our thinking selves. Habits are where we are most likely to accept the first explanation offered. Use the interactive below to reveal the rest of the scene one clue at a time, and watch what happens to the list of possible motives.

Which motive was dominant?

A harder question follows the first three motives: which one was dominant in the scene just described? Probably the cultural image or the attraction, this time anyway. Ask Sam tomorrow, when he is barely awake, and health, or habit, or fresh breath may be the truthful answer. The point is that motives are layered and situational. A person does not carry one reason for a behaviour; they carry a repertoire, and the setting selects from it.

The questions

The moral of the story is that an entire field of study and practice exists around the complex nature of health behaviour, with the goal of implementing programs and interventions that promote change in behaviour in order to improve the health of the public or a segment of it. You already know these programs: campaigns to stop smoking, warnings on cigarette packaging and lawsuits against tobacco companies, school programs and television advertisements about drugs, alcohol, and drinking and driving, billboard and transit advertising about HIV risk and the benefits of testing, and public campaigns about cardiovascular health and diet. Canada has run versions of every one.

Most of these programs rest on a body of knowledge about what motivates and influences human behaviour. The public health question, therefore, is: why do people behave in healthy (or unhealthy) ways? And that question is a focused version of a much older one: why do people do what they do? To understand the subset of behaviour we label health behaviour, we have to think about it in the context of what generally motivates or influences behaviour of any kind.

When health is not the motive

The Sam scenario shows that behaviour categorized as health behaviour is not necessarily motivated or influenced by concerns about health. There are four possibilities. Click each card.

The fourth possibility deserves emphasis because it will return when this lesson turns to obesity. The case in point is body size: for many peoples who have experienced food shortage through their history, a large man, one we might call overweight, is viewed as healthy and doing well. Thinness is a symbol of starvation. This is a different definition of health. A weight-loss program that ignores it will be ineffective, and worse, it will be asking people to pursue what they understand as illness.

When motivation is beside the point

The final move in this section is to shift the ground entirely. Often, what people do or do not do about their health has more to do with socioeconomic circumstances, environmental conditions, or public policies and regulations than with motivation at all. Consider three cases, each of which has a Canadian counterpart.

Each of these cases anticipates the next section. The examples illustrate the complexity of factors that influence behaviour, and that complexity is what the ecological model was built to organize.

Behaviour does not exist in a vacuum

The cases that closed the last section, the rural woman and the mammogram, the fishing community downstream from a factory, the village that became a city, illustrate the complexity of factors that influence behaviour. This section gives that complexity a name and a structure. The name is the ecological model. The structure is a set of levels at which influences operate, drawn as nested rings.

From individual motives to the web

Until the late 1970s and early 1980s, health promotion professionals and programs focused primarily on the knowledge, attitudes, and motivations of individuals, without much attention to the social, cultural, and economic circumstances that are also major determinants of behaviour. If people knew the risks and wanted to avoid them, the reasoning went, they would change. The planning work of Green and Kreuter is usually credited with the turn that followed. The more recent focus on the multiplicity of influences on behaviour is what is called the ecological model.

The definition is worth reading slowly. Under this model, it is assumed that no single factor influences people's behaviour; instead, the complex interaction between individuals and an environment is a process that, taken together, influences behaviour. Two words carry the weight. The first is interaction: people and environments act on each other, so studying one and then the other misses the process. The second is environment, which here means that which exists outside the individual, so it includes the social environment as well as the physical one. Family, peers, institutions, laws, and prices are environment in this sense, along with air and water.

Canadian and global milestones

The ecological model is closely related to a perspective advocated by the World Health Organization known as the social determinants approach, set out in the Rio Political Declaration of 2011. Canada arrived at similar conclusions on its own timeline, and two of the documents that shaped health promotion internationally were written here. Use the tabs to compare them.

Indigenous-led frameworks in Canada arrive at the same structure from a different starting point. The First Nations Health Authority in British Columbia, the first province-wide First Nations health authority in the country, describes health and wellness with a schematic that places the person at the centre, surrounded by family, community, nations, and land, and finally by social, environmental, cultural, and economic determinants. The vocabulary differs, but the claim that a person's health is produced by the layers around them is the same.

Five groups of factors

Here is a sampling of potential contributors to the behaviour of individuals, sorted into five groups. Open each group to see examples and a Canadian illustration.

One point deserves emphasis: this list does not operate in the world as a collection of separate items. The factors tend to operate together. That is why the model borrows the term ecology from biology, where it refers to a system of interactions between organisms and an environment, to the complex relationships among organisms within the system (niches, for example), and to the dependent relationships among the parts, such that if one part is disturbed, the others are affected.

Levels of influence

The human version of that ecology is usually drawn as nested levels. The individual sits at the centre. Around the individual is the family and social group, then the community or population group, then the cultural and societal level, and finally the political, economic, and structural level. Arrows run in both directions: influences flow inward through the layers, and behaviour flows back out and reshapes them.

Notice that the rings and the five-group list do not match one for one. The list separates political, structural, and environmental factors; the figure folds them into an outer ring and adds explicit community and cultural layers. Both are sorting tools rather than fixed taxonomies, and an influence can plausibly sit in more than one place. What matters is the habit of asking, for any behaviour, what is acting on it at each level. The sorter below gives you practice.

Respecting complexity

Answering "Why do people do what they do?" or its public health version is, admittedly, no easy matter. Yet to know this is good. Gaining a certain respect for the complexity of the task is healthy, because if you think the problem is simple you are more likely to implement a standardized or cookie-cutter program without much thought about whether it fits the situation. One goal of this course is that you emerge with more wisdom than that.

None of this is a reason to throw up your hands. A long tradition of researchers and practitioners has built up a considerable store of scientific knowledge, interpretive understanding, and practical application with respect to changing behaviour. There are many schools of thought and many disagreements about what should be the focus of attention. The remainder of this course does three things with that tradition: it reviews theoretical approaches and their assumptions so that you can judge which make sense in a given situation; it presents a general planning approach for assessing a problem, deciding what kind of program might change it, and determining whether you succeeded; and it tours the settings and health problems, including smoking, cancer, cardiovascular disease, HIV/AIDS, maternal and child health, youth violence, and obesity, where the theory gets applied. Treat the course as a resource for an ongoing search for answers rather than a compendium of the answers themselves.

Two problems, one model

The second half of this lesson exists to show why an understanding of behaviour matters for public health problems. For each of three health issues it asks which behaviours are involved, what consequences follow, and what shapes those behaviours, with one framing sentence that is easy to skip: behaviour is just one factor that determines a health problem, and behaviour is itself influenced by many factors. This section covers obesity and youth violence.

Obesity: a recent trend, and therefore a preventable one

Start with scale: more than two thirds of American adults overweight or obese in 2008 to 2009, childhood obesity five times its early-1970s level, and about 1.5 billion overweight adults worldwide by World Health Organization estimates, with rapid increases in China, Brazil, Colombia, and urban sub-Saharan Africa. Statistics Canada surveys have for years found more than one Canadian adult in four with a body mass index in the obese range. The consequences named are type 2 diabetes, heart disease, certain cancers, and healthcare costs.

Where does behaviour come in? Because these trends are recent, most researchers agree that interactions between behaviour and environment, rather than biology, are the primary cause, which is what makes the problem preventable. The usual list of causes deliberately mixes behaviours with the environments that produce them: marketing of unhealthy food, overeating, lack of exercise, reliance on vehicles, a sedentary life built around screens, changes in food quality, larger portions, eating out, the convenience food industry, and more advertising. Then ask yourself directly: how often do you eat out, and how often do you exercise?

Why knowledge alone fell short

For a while, public health efforts concentrated on awareness: guidelines for diet and exercise, warnings about excess weight, personal knowledge and skills. These produced moderate short-term successes and did not prove effective in the long term. Critics pointed to an overreliance on what individuals can and cannot do, at the expense of the sociocultural and physical environments that shape their decisions. Many of those efforts used the individual behaviour change theories you will meet later in the course.

Here a point is easy to miss. The shortfall cannot necessarily be fixed by adding an individual-level intervention to an environmental one, because behaviour and the environment interact: they act upon one another. This is where ecological models come in. They integrate interpersonal, organizational, community, and policy influences, and an ecological intervention includes components at several levels designed so that an environmental change supports a behaviour change. The classic example is small and concrete: removing vending machines, or changing what they sell, cuts down on high-fat snacking.

Youth violence

The second issue is a behaviour rather than a condition; the public health concern is the injury and trauma that violence causes. The World Health Organization views violence as one of the leading public health issues of our time, and interpersonal violence among people aged 15 to 29 accounted for 36.2 percent of the violent deaths it reported. In the United States, homicide was the second leading cause of death for ages 10 to 24 in 2007, 83 percent of those victims were killed with a firearm, and the burden fell far more heavily on African American and Latino youth. Canada's homicide rate is a fraction of the American rate, but here too, youth and young adults have the highest rates of both committing and experiencing violent crime.

Serious violence generally begins between ages 12 and 20, so the peak period coincides with adolescence. Why? Beyond biological and developmental accounts of aggression, there is a set of social and psychological explanations that concern the interaction between youth and their family, community, and school environments, and that often treat violence as one of a set of adolescent risk behaviours. Open each of the six.

Read the six as a set. Each locates the cause at a different level of the web and implies a different program; a serious program draws on several.

A pandemic tied to behaviour

The third health issue is the one where the link between behaviour and disease is most direct. Human immunodeficiency virus (HIV) passes from person to person through a small number of acts, every one of which is a behaviour or its direct result. That makes HIV/AIDS the clearest demonstration of this lesson's argument, and the clearest warning against reading behaviour apart from the moral, cultural, and economic systems around it. This section works through the global picture, the regional patterns, and the Roma study, then turns to Canada and closes with the three-step path from behaviours to interventions.

The toll, and why prevention carries the burden

Data from the end of 2011 put approximately 34 million people living with HIV/AIDS, nearly 30 million deaths since the 1980s, and roughly 2.5 million new infections a year, a sign the pandemic was still expanding. The toll reaches past illness: lower life expectancy, lost household income, depleted schools, lower economic production, rising poverty, and a generation of orphaned children. More recent UNAIDS estimates put the number living with HIV near 40 million, with new infections and deaths well below the 2011 levels, largely because of treatment.

HIV has been a crisis filled with ambiguity and controversy for two reasons that belong together: its epidemiology, the way it spreads, is clearly tied to behaviour, and although anti-retroviral drugs, given in combinations known as highly active anti-retroviral therapy (HAART), can treat the condition, there is still no cure. That places a huge burden on prevention, and prevention is largely about behaviour.

Understandings of sexual behaviour sit at the centre of the moral and religious systems of virtually every society, and sexual behaviour is tied to gender relations and, inescapably, to poverty and wealth. To understand transmission in a particular place you have to look at all of these, and that still leaves out the risks people take without knowing it.

Different places, different epidemics

Patterns of spread vary by country, gender, and subgroup, and change as an epidemic evolves. Read the six sketches for the context behind each pattern.

Canada's epidemic and the shift in prevention

The Public Health Agency of Canada estimated that roughly 65,000 people were living with HIV in Canada at the end of 2022, most but not all diagnosed. Gay, bisexual, and other men who have sex with men account for the largest share of new diagnoses; people who inject drugs are the second group; and Indigenous people and African, Caribbean, and Black communities appear among new diagnoses well out of proportion to their population share. Saskatchewan has reported a diagnosis rate well above the national rate for more than a decade, much of it linked to injection drug use. Behind each pattern lie stigma, poverty, colonial history, and uneven access to testing and care.

What has changed most since the 1980s is the toolkit. The interactive below traces the Canadian shift to combination prevention. Click each event and note the last line, which names the behaviour the tool still depends on.

The questions before the program

Each route involves many behaviours that vary across cultures and circumstances, so before designing anything a practitioner needs answers to questions like these.

Notice how few of these questions are about knowledge, and how many are about setting, power, necessity, and options. That is the ecological model as a set of assessment questions.

Behaviours, theories, and interventions

This lesson closes with its central practical claim. All three health issues show the complex link among behaviour, social and environmental factors, and a health problem. The theories in the rest of the course are tools for working through that web, and figuring out what to do is made a little easier by a three-step process.

The order matters. Assessment comes first, and it is ecological. Theory is chosen to fit what the assessment found, which is why the course spends several lessons on theories before turning to planning. The program follows from both. Lesson 2 takes up the word that has been doing quiet work throughout this lesson and asks what a theory actually is.

Bringing It All Together

This lesson began with a friend brushing his teeth and ended with a provincial HIV program, and the same idea ran through both. Sam's toothbrushing had at least six candidate motives, from cavities to a magazine cover to a mother who had lost her own teeth, and the dominant motive shifted with the day and the setting. Two lessons follow from that scene. First, the public health question, why do people behave in healthy or unhealthy ways, is a focused version of the general question of why people do what they do, so understanding health behaviour means drawing on everything we know about behaviour. Second, behaviour labelled as health behaviour may be motivated by health, by health mixed with other concerns, by something unrelated to health, or by an idea of health that differs from Western medicine's. And often motivation is beside the point, because circumstance, environment, and policy set the terms before any motive has a say.

The ecological model gives that observation a structure. Since the late 1970s and early 1980s, health promotion has moved from a focus on individual knowledge, attitudes, and motivation toward the assumption that no single factor influences behaviour and that people and their environments, social as well as physical, act on each other. Influences can be sorted into five groups of factors, individual, social and cultural, socioeconomic and structural, political, and environmental, and drawn as nested levels of influence. The World Health Organization's social determinants approach and the Rio Declaration state the same claim at the level of populations; the Lalonde Report and the Ottawa Charter mark the same turn in Canada. Respecting this complexity is what keeps a practitioner from importing a cookie-cutter program into a place it does not fit.

The second half of the lesson put the model to work. Obesity showed that education alone produced short-term change and that lasting change requires environments that support behaviour, from vending machines to trails to food policy. Youth violence showed that one behaviour can be explained at six different levels, from a young person's reading of a facial cue to the economics of an isolated neighbourhood, and that the explanations intersect. HIV/AIDS showed transmission routes that are all behaviours, patterns that differ by place and change over time, and, in Canada, a prevention toolkit that has broadened from behaviour change alone to combination prevention while still depending on what people do. The lesson closed with a three-step path that the rest of the course follows: identify what is going on, choose the theories that fit, and design the program.

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.