Source: Health Psychology, 11th Edition by Taylor, Chapter 1
Difficulty: Introductory | Prerequisites: None. This is the opening chapter of the course.
This chapter lays the groundwork for the entire health psychology course. It explains what health psychology is, traces how our understanding of illness evolved from ancient humoral theory through the biomedical model to the modern biopsychosocial model, and introduces the research methods used in the field. If you are joining mid-semester, start here: every later chapter builds on these models and terms.
Health psychology studies how psychological, behavioural, and social factors influence health, illness, and healthcare. The field moved beyond the purely biological "biomedical model" to embrace the "biopsychosocial model," which treats mind, body, and social environment as inseparable. Research in the field ranges from controlled experiments and clinical trials to correlational, prospective, and retrospective designs.
Health psychology
The study of psychological influences on how people stay healthy, why they become ill, and how they respond when they get ill.
In simple terms, it is the branch of psychology that looks at the mental and behavioural side of physical health.
Health
Defined by the World Health Organization (1948) as "a complete state of physical, mental, and social well-being and not merely the absence of disease or infirmity."
Think of it as: health is not just "not being sick" but thriving across body, mind, and social life.
Etiology
The origins or causes of a disease or illness.
In simple terms, the "why" behind getting sick.
Epidemiology
The study of the frequency, distribution, and causes of infectious and non-infectious diseases in a population.
Think of it as: tracking who gets sick, where, and why, on a population level.
Morbidity
The number of cases of a disease that exist at a given point in time.
Incidence
The number of new cases of a disease at a given point in time.
Prevalence
The total number of existing cases of a disease (new and old combined).
Mortality
The number of deaths due to a particular cause.
Biomedical model
A model of illness that assumes all illness can be explained by aberrant somatic (bodily) processes, such as disordered cells or chemical imbalances. It treats mind and body as separate (mind-body dualism) and emphasises illness over health.
Biopsychosocial model
A model holding that biological, psychological, and social factors are all important determinants of health and illness. It replaced the biomedical model as the dominant framework in health psychology.
Think of it as: health sits at the intersection of biology, thoughts/feelings, and social environment.
Psychosomatic medicine
A field built on the belief that profiles of particular disorders are caused by emotional conflicts. Pioneered by Flanders Dunbar and Franz Alexander.
In simple terms, the idea that unresolved psychological tension can produce real physical symptoms.
Conversion hysteria
A term used by Sigmund Freud for a specific unconscious conflict that produces physical disturbances and symbolises repressed psychological conflicts.
Humoral theory of illness
An ancient model proposing that disease occurs when four bodily fluids (humours) are out of balance: blood, black bile, yellow bile, and phlegm.
Acute disorders
Short-term illnesses that are usually amenable to cure (e.g. influenza, pneumonia).
Chronic illnesses
Slowly developing diseases with which people live for many years and that are not curable, only manageable (e.g. cancer, heart disease, diabetes). Social factors are implicated as causes.
Randomised clinical trial (RCT)
An experiment conducted by a healthcare practitioner to evaluate treatments or interventions, in which a target treatment is compared against an inert (control) treatment and participants are randomly assigned.
Evidence-based medicine
A medical intervention that goes through rigorous testing and evaluation of its benefits, usually through randomised clinical trials.
Correlational research
Research that measures whether a change in one variable corresponds with changes in another. Its major disadvantage is that the direction of causation is unclear.
Prospective research
Research that looks forward in time to see how a group of people change, or how a relationship between two variables changes over time.
Longitudinal research
A type of prospective study where the same people are observed at multiple points in time.
Retrospective design
Looking backward in time to reconstruct the conditions that led to a current situation.
Meta-analysis
A method that combines results from different studies to identify how strong the evidence is for a particular research finding. Powerful because it uses a broad array of diverse evidence.
Ecological momentary interventions
Interventions that use mobile technologies (phones, tablets, pagers) to deliver interventions and assess health-related events in the natural environment.
Health promotion
Efforts to help people develop healthy behaviours and lifestyles, such as community exercise programmes for older adults.
Health psychology is the study of psychological influences on how people stay healthy, why they become ill, and how they respond when they get ill. It is distinct from general psychology (which covers mental health, education, ergonomics, law) and from biology or medicine.
Health promotion and maintenance – designing interventions (e.g. media campaigns about diet) that encourage healthy behaviours
Prevention and treatment of illness – helping people already ill to follow treatment regimens; developing lifestyle interventions targeting health behaviours
Etiology and correlates of health, illness, and dysfunction – studying the behavioural and social factors (e.g. smoking, alcohol) that contribute to disease
The healthcare system and health policy – studying the impact of hospitals and physicians on behaviour to develop recommendations for improving care; understanding what makes people satisfied or dissatisfied with their healthcare
The World Health Organization defined health as "a complete state of physical, mental, and social well-being and not merely the absence of disease or infirmity." This was significant because it encompasses social, mental, and physical health, moving well beyond the older view that health simply meant "not being sick."
The earliest systematic model of illness. Disease occurs when the four bodily fluids (humours) are out of balance:
Blood – associated with a passionate temperament
Yellow bile – associated with an angry disposition
Black bile – associated with sadness
Phlegm – associated with a laid-back approach to life (not sadness, a common mix-up)
The humoral theory was replaced by the science of cellular pathology during the Renaissance, which located disease at the level of individual cells.
The rise of mind-body dualism in the Middle Ages was an advantage because it allowed the physical body to be examined scientifically, separating it from the realm of the soul and the Church.
This dualism underpins the biomedical model, which maintains that:
All illness can be explained on the basis of aberrant somatic bodily processes (disordered cells, chemical imbalances)
Mind and body are separate entities
The model emphasises illness over health
It reduces illness to low-level biological processes
It does not account for psychological or social factors
It does not recognise healthcare providers as a powerful influence on patient health
The biomedical model dominated Western medicine for centuries but has significant blind spots. It cannot explain why two people exposed to the same pathogen might have different outcomes, because it ignores the psychological and social context.
Sigmund Freud introduced the concept of conversion hysteria: the idea that a specific unconscious conflict can produce physical disturbances that symbolise repressed psychological conflicts.
Flanders Dunbar and Franz Alexander built on this, arguing that emotional conflicts produce anxiety, which becomes unconscious and takes a physiological toll on the body via the autonomic nervous system. They developed profiles linking personality types to specific disorders. Franz Alexander, for instance, described the ulcer-prone personality as someone with excessive needs for dependency and love.
A psychosomatic clinician in the early 1900s would most likely diagnose conditions such as colitis (rather than infections like tuberculosis or diphtheria), because colitis was believed to have a psychological origin.
Psychosomatic medicine's lasting contribution: it established that psychological factors play a role in physical illness. Its limitation: researchers now know that a single personality profile or emotional conflict is not sufficient to produce a disorder. Disease onset typically involves multiple factors working together, including biological pathogens, stress, low social support, and socioeconomic status.
The biopsychosocial model emerged from the recognition that mind and body together determine health and illness. It holds that:
Biological, psychological, and social factors are all important determinants of health and illness
Both macro-level (e.g. social support, socioeconomic status) and micro-level (e.g. cellular, chemical) processes interact continually
Health is achieved by being attentive to biological, psychological, and social needs
It emphasises both health and illness (unlike the biomedical model, which focuses on illness alone)
It stresses the importance of an effective patient-practitioner relationship
A health psychologist studying the link between positive interactions in close relationships and the physiological stress response (as in the textbook's Dr. Karumbe example) is working squarely within this model.
The shift from biomedical to biopsychosocial thinking is why modern healthcare teams include not only doctors but also psychologists, social workers, dieticians, and physical therapists. A social worker assesses where patients go after discharge. A physical therapist helps patients regain bodily functions compromised by illness. Health psychologists work on treatment adherence, pain management, and quality of life.
Students often confuse etiology (causes of illness) with epidemiology (study of disease distribution in populations). Etiology asks "why does this disease happen?" Epidemiology asks "who gets it, where, and how often?"
Students mix up morbidity (number of cases) with mortality (number of deaths). Morbidity = sickness rate. Mortality = death rate.
Students confuse incidence (new cases) with prevalence (total existing cases). Incidence counts only fresh diagnoses; prevalence includes everyone currently living with the condition.
Phlegm in the humoral theory is associated with a laid-back temperament, not sadness. Black bile is the one linked to sadness.
⚠️ The four humours and their associated temperaments are heavily tested. Commit to memory: blood = passionate, yellow bile = angry, black bile = sad, phlegm = laid-back.
⚠️ Know the difference between the biomedical and biopsychosocial models cold. Exam questions frequently ask you to identify which model a scenario describes.
⚠️ The WHO (1948) definition of health encompasses physical, mental, and social well-being. This is a favourite multiple-choice item.
⚠️ Understand that the biomedical model assumes mind-body dualism, while the biopsychosocial model integrates them.
⚠️ Psychosomatic medicine's key claim: emotional conflicts produce physiological symptoms via the autonomic nervous system. Know the names Dunbar and Alexander.
⚠️ The division of health psychology was formed in 1978 within the American Psychological Association (APA).
True or False: The biomedical model emphasises health over illness. (False – it emphasises illness over health.)
Fill in the blank: The humoral theory was replaced by the science of __________ during the Renaissance. (Cellular pathology.)
True or False: According to the humoral theory, phlegm is associated with sadness. (False – phlegm is associated with a laid-back temperament. Black bile is associated with sadness.)
Fill in the blank: __________ refers to the number of new cases of a disease at a given point in time. (Incidence.)
True or False: The biopsychosocial model emphasises the importance of an effective patient-practitioner relationship. (True.)
Q: Which of the following best defines health psychology?
A: Understanding the psychological influences on how people stay healthy, why they become ill, and how they respond when they get ill.
Q: What does the WHO's 1948 definition of health encompass?
A: Social, mental, and physical health. It defines health as "a complete state of physical, mental, and social well-being and not merely the absence of disease or infirmity."
Q: A health psychologist designs a media campaign to improve people's diets. Which focus area is this?
A: Health promotion and maintenance.
Q: According to the humoral theory, which bodily fluid is associated with an angry disposition?
A: Yellow bile.
Q: What is the key assumption of the biomedical model?
A: That all illness can be explained on the basis of aberrant somatic bodily processes (disordered cells, chemical imbalances). It assumes mind-body dualism.
Q: What distinguishes the biopsychosocial model from the biomedical model?
A: The biopsychosocial model holds that biological, psychological, and social factors all determine health and illness. It emphasises both health and illness and stresses the patient-practitioner relationship. The biomedical model focuses only on biological processes and emphasises illness over health.
Q: Flanders Dunbar and Franz Alexander argued that emotional conflicts take a physiological toll via which system?
A: The autonomic nervous system.
Q: What is the difference between acute and chronic disorders?
A: Acute disorders are short-term illnesses usually amenable to cure (e.g. pneumonia). Chronic illnesses are slowly developing, long-term diseases that are managed rather than cured (e.g. cancer, heart disease), and social factors are implicated in their causation.
This chapter's models (biomedical vs. biopsychosocial) reappear throughout the course. The biopsychosocial framework is the lens through which later chapters examine stress and coping (Ch. 6-7), chronic illness management, pain, and patient-provider communication. The research methods introduced here (RCTs, prospective designs, meta-analysis) are the tools used to evaluate every intervention discussed later.
The shift from acute to chronic illness as the leading cause of death (Ch. 1's historical context) is the reason health psychology exists as a field. Without that epidemiological shift, there would be far less need for behavioural and psychological approaches to healthcare.
health psychology definition, WHO definition of health 1948, biopsychosocial model, biomedical model, mind-body dualism, humoral theory four humours, etiology vs epidemiology, morbidity vs mortality, incidence vs prevalence, psychosomatic medicine, conversion hysteria Freud, Flanders Dunbar, Franz Alexander, acute vs chronic illness, health promotion, randomised clinical trial, evidence-based medicine, correlational research, prospective research, retrospective design, longitudinal research, meta-analysis, ecological momentary intervention, Taylor health psychology 11th edition chapter 1