Source: Textbook Ch. 3 / Lecture Notes
Difficulty: Intermediate | Prerequisites: Part 1 of these notes (Health Behaviour and Change Fundamentals).
Part 1 covered what health behaviours are and what influences them. This part asks a different question: what theoretical models explain how and why people change? These models are the backbone of health psychology research and intervention design. Each offers a different lens, from rational decision-making (Health Belief Model) to staged readiness (Transtheoretical Model) to intrinsic motivation (Self-Determination Theory). You need to know not just what each model says, but where it falls short.
Several theoretical models attempt to explain health behaviour change. Attitude-based models (Health Belief Model, Theory of Planned Behaviour) focus on how beliefs and perceived control shape intentions. The Transtheoretical Model maps change as a series of stages people cycle through, often with relapse. Each model has real limitations, and a recurring critique is that they overemphasise conscious, individual-level decision-making while neglecting culture, context and unconscious processes.
Self-efficacy
One's belief in their ability to control or perform a particular behaviour. In simple terms, it is the confidence that you can do the thing you are trying to do, whether that is quitting smoking or starting an exercise routine.
Health Belief Model (HBM)
A model proposing that health behaviour is influenced by perceived health threat and perceived threat reduction. Think of it as a cost-benefit calculation: "How likely is it that I will get sick?" combined with "Will this action reduce that risk?"
Theory of Planned Behaviour (TPB)
A model stating that behavioural intention (and thus behaviour) is shaped by three factors: attitudes toward the behaviour, subjective norms (what important others think), and perceived behavioural control (whether you believe you can do it).
Self-Determination Theory (SDT)
A theory proposing that people are actively motivated to pursue goals, with behaviour change depending on autonomous motivation (internal drive) and perceived competence (belief in one's own ability).
Transtheoretical Model (TTM) / Stages of Change
A model that maps behaviour change as a progression through stages: precontemplation, contemplation, preparation, action, maintenance, and (rarely) termination. In simple terms, it recognises that people are not all at the same starting point and that change is a process, not a single event.
Implementation intentions
A strategy that integrates conscious processing with automatic behavioural enactment by delegating goal-directed responses to situational cues. Think of it as pre-programming your behaviour: "When X happens, I will do Y."
Abstinence violation effect
The feeling of loss of control that results when a person violates their own self-imposed rules. A classic example: someone who has quit smoking lights up one cigarette and then feels the entire effort has failed, which can trigger a full relapse.
Message framing
The way health information is presented, which affects how persuasive it is. Effectiveness depends on the type of message and the audience's existing motivation.
Three main approaches to changing attitudes about health:
Educational appeals: Provide people with good information about their habits. The premise is straightforward: if people know the facts, they will change. This works in some cases but is rarely sufficient on its own.
Fear appeals: Try to scare people into changing by explaining how a habit may be hurting them. People do change behaviours they fear are damaging their health, but fear alone has limits.
Message framing: How you present health information matters as much as the information itself.
Effectiveness depends on the type of message and the audience's motivation.
Communications should be colourful and vivid, not buried in statistics. Case histories help.
The communicator should be expert, credible, likeable and similar to the audience.
Strong arguments belong at the beginning and end of a message, not hidden in the middle.
Messages should be short, clear and direct, with explicit conclusions.
Extreme messages can produce more attitude change, but only up to a point, as very extreme messages get dismissed.
If the audience is receptive, present only favourable points. If the audience is resistant, present both sides.
Interventions should be sensitive to the cultural norms of the community they target.
The HBM focuses on two core perceptions that influence health behaviour:
Perceived health threat: How susceptible does the person believe they are, and how severe do they think the consequences would be?
Perceived threat reduction: How effective does the person believe a given action would be in reducing that threat, weighed against the costs of taking that action?
The model is used to increase perceived risk and perceived effectiveness of protective steps. It works well for one-time decisions (getting a vaccination) but less well for ongoing behaviour change.
A notable limitation: the HBM leaves out self-efficacy. It addresses whether you think an action would help but not whether you believe you are capable of carrying it out. This omission is significant, because confidence in one's own ability is often the deciding factor in whether someone follows through.
The TPB holds that health behaviour flows from behavioural intention, which is shaped by three inputs:
Attitudes toward the behaviour: What do you believe the outcomes will be, and do you value those outcomes? ("If I change my diet, I will lose weight, improve my health and look better. Being healthy and looking good are desirable.")
Subjective norms: What do the people who matter to you think you should do, and how motivated are you to comply? ("My family and friends think I should change my diet. I want to do what they want.")
Perceived behavioural control: Do you believe you have the ability to carry out the behaviour? ("I will be able to change my diet.")
All three feed into behavioural intention ("I intend to change my diet"), which then leads to the actual behaviour (adopting a healthier diet).
SDT takes a different approach from the belief-based models. It starts from the premise that people are actively motivated to pursue their goals. Two components are fundamental to behaviour change:
Autonomous motivation: Can you internalise the behaviour so it feels self-directed rather than imposed? Change that comes from within is more durable than change driven by external pressure.
Perceived competence: Do you believe you are capable of performing the new behaviour? This overlaps with self-efficacy but is framed within SDT's broader motivational framework.
The TTM maps behaviour change as a progression through distinct stages:
Precontemplation: The person is not yet seriously considering that they have a problem. They might be smoking heavily and only beginning to notice it could be an issue.
Contemplation: The person is actively thinking about change. "What would my life be like if I quit smoking?"
Preparation: The person is actively preparing to quit the problematic behaviour but has not yet committed fully.
Action: The person implements the change. This requires genuine desire to change, not just external pressure.
Maintenance (6+ months): The person works to sustain the new behaviour long-term. The most vulnerable period for relapse is around six months.
Termination: Rarely reached. Many people remain in the maintenance phase for life.
The model is often visualised as a spiral rather than a straight line. People cycle through the stages, relapsing and re-entering at earlier points before eventually progressing. Relapse may be the rule rather than the exception.
How well does the TTM hold up?
Still popular and applies across many types of psychological change.
Staged interventions (matching the intervention to where someone is in the process) tend to be more effective than one-size-fits-all approaches.
Critiques include: arbitrary timing of stages, mixed results in testing, and no mention of culture or contextual factors.
Criticisms of attitude theories specifically:
Interventions based on these models may not always provide sufficient impetus to take action. Knowing is not the same as doing.
They assume behaviour change is guided by conscious motivation, even though much of it is driven by unconscious processes.
They ignore that behaviour changes can occur automatically, outside of awareness.
Implementation intentions address one of these gaps by integrating conscious planning with automatic enactment. By delegating goal-directed responses to situational cues ("If it is 7 a.m., I will go for a run"), you bridge the gap between intention and action.
Health behaviour change and the brain also complicate the picture: behaviour change in response to persuasive messages can occur outside of awareness, reflected in activation patterns of the medial prefrontal cortex (mPFC) and posterior cingulate cortex (pCC).
Broader critiques of health psychology theories:
Too focused on the individual level, neglecting social and structural factors.
Lack ecological validity (laboratory findings may not translate to real-world settings).
Rely mostly on self-report measures.
Neglect culture, religion and gender.
Often unfalsifiable, meaning there is no clear way to prove they do not work.
Students often conflate the Health Belief Model with the Theory of Planned Behaviour. The HBM is about perceived threat and perceived benefit of action; the TPB adds subjective norms and perceived behavioural control. A key differentiator: the HBM leaves out self-efficacy; the TPB includes it as perceived behavioural control.
Students sometimes treat the TTM stages as a straight line. The model is better understood as a spiral: people cycle through stages, often relapsing before progressing.
It is common to assume that providing information (educational appeals) is enough to change behaviour. Research consistently shows that knowledge alone rarely drives change without motivation, self-efficacy and social support.
Students often forget the criticisms of these models. Exams frequently ask about limitations, not just descriptions.
⚠️ Be able to compare the HBM and TPB side by side, including what the HBM leaves out (self-efficacy).
⚠️ Know the six stages of the Transtheoretical Model in order, and understand the spiral nature of the process.
⚠️ Understand what the abstinence violation effect is and why relapse prevention should be built into treatment from the start.
⚠️ Be ready to list at least three criticisms of health psychology theories in general (individual-level focus, self-report reliance, cultural neglect, unfalsifiability).
⚠️ Know the difference between autonomous motivation and perceived competence in Self-Determination Theory.
⚠️ Message framing principles are frequently tested: remember that receptive audiences get one-sided messages while resistant audiences get both sides.
True or False: The Health Belief Model includes self-efficacy as a core component. (False, it leaves out self-efficacy.)
Fill in the blank: In the Transtheoretical Model, the stage where a person is actively thinking about change but has not yet acted is called ______. (Contemplation)
True or False: The Theory of Planned Behaviour considers subjective norms (what others think). (True)
Fill in the blank: The feeling of loss of control after violating a self-imposed rule is called the ______ ______ effect. (Abstinence violation)
True or False: When presenting health messages to a resistant audience, you should present only the favourable side. (False, present both sides.)
Q: What are the two core perceptions in the Health Belief Model?
A: Perceived health threat (susceptibility + severity) and perceived threat reduction (effectiveness of action minus its costs).
Q: How does the Theory of Planned Behaviour differ from the Health Belief Model?
A: The TPB includes subjective norms (what important others think) and perceived behavioural control (self-efficacy), which the HBM does not. The TPB also focuses on behavioural intention as the pathway to action.
Q: List the six stages of the Transtheoretical Model in order.
A: Precontemplation, contemplation, preparation, action, maintenance, termination.
Q: Why is the TTM described as a spiral rather than a straight line?
A: Because people often cycle through the stages multiple times, relapsing and re-entering earlier stages before eventually progressing. Relapse is a common part of the change process, not a failure.
Q: What is the main criticism shared by most attitude-based models of health behaviour change?
A: They assume behaviour change is consciously driven, when much of it is influenced by unconscious processes, habits and contextual factors. They also tend to operate at the individual level, neglecting social, cultural and structural influences.
Q: What is an implementation intention, and what gap does it fill?
A: An implementation intention links a situational cue to a planned behaviour ("When X happens, I will do Y"). It bridges the gap between conscious intention and automatic action, addressing the criticism that attitude models fail to account for automatic behaviour.
These models connect to the CBT and intervention strategies covered in Part 3 of these notes (cognitive-behavioural approaches, motivational interviewing, relapse prevention). The Transtheoretical Model in particular informs how clinicians choose which intervention technique to use at which point. The criticisms section links back to broader debates in psychology about ecological validity, cultural sensitivity and the limitations of self-report data.
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