Health Behavior Change Theories – Detailed Study Notes

“Health behaviors” (a.k.a. healthy behaviors) = any routine actions that promote or maintain health.
- Examples: quitting smoking, starting an exercise program, adopting a balanced diet, using seatbelts, getting vaccinated.
Understanding the psychology behind these choices allows public-health professionals to craft messages, design interventions, and pass policies that increase healthy behaviors and decrease risky ones.
The lecture presents three core theories/models used in behavioral health science:
1. Health Belief Model (HBM)
2. Theory of Planned Behavior (TPB)
3. Transtheoretical / Stages-of-Change Model (TTM)
Note the disciplinary overlap between psychology, behavioral sciences, epidemiology, and policy (e.g., CDC or WHO health-promotion campaigns).

Historical origin: surveys in early $20^{\text{th}}$ -century U.S. to explain why citizens resisted the new tuberculosis (TB) vaccine.
Core premise: a person’s decision to act is primarily driven by their perceived threat of the condition.
Key constructs (measured via questionnaires, interviews, or psychometric scales):
- Perceived Susceptibility
- “Could this happen to me?”
- If one does not feel personally at risk, they will rarely change.
- Perceived Severity
- “If it happens, how bad will it be?”
- Mild illnesses (e.g., the common cold) evoke low severity; severe outcomes (e.g., lung cancer) evoke high severity.
- Perceived Threat = Perceived Susceptibility $+$ Perceived Severity.
- Perceived Benefits & Barriers
- A pros–cons ledger. Benefits: better breathing, fewer hospital visits. Barriers: nicotine cravings, social smoking breaks.
- Cues to Action
- External or internal prompts: family urging, Instagram infographics, news footage of emphysema patients, physician advice, etc.
Predictive utility: Researchers quantify each construct to forecast whether someone will act (e.g., vaccinate, buckle seatbelts).
Practical example: anti-smoking ads that display diseased lungs amplify perceived severity, hoping to tip the cost–benefit scale.
- Caution: overly graphic content can backfire—viewers may disengage or deny susceptibility.

Developed to refine attitude–behavior links by adding the idea of perceived behavioral control.
Central axiom: the strongest direct predictor of behavior is Behavioral Intention—i.e., “I plan to do X.”
Three determinants of intention (two overlap with HBM):
1. Attitude toward the behavior (≈ perceived benefits & barriers)
- Personal evaluation: “Overall, quitting will help me breathe easier.”
1. Subjective Norms (≈ cues to action)
- Social pressure & modeling: “Everyone in my friend group vapes—quitting might isolate me.”
1. Perceived Behavioral Control (PBC) —unique to TPB
- Self-efficacy: “Can I actually pull this off?”
- Repeated failed quit attempts (e.g., $20$ past tries) lower PBC.
If attitude $+$ norms $+$ PBC align positively, intention strengthens, making behavior change more probable.
Use cases: diet adherence, exercise uptake, condom use, medication compliance—especially when the main hurdle is skill or resources, not fear.

Focus: process of change, not the “why.” Depicted as an upward spiral.
Stages (cyclical):
1. Pre-contemplation – No recognition of need/wish to change.
2. Contemplation – Acknowledges problem; no commitment yet.
3. Preparation – Formulating a plan: researching patches, picking a quit date.
4. Action – Overt modification: actually stops smoking.
5. Maintenance – Sustains new behavior; employs coping skills.
6. Relapse – Temporary return to old habit; seen as normal, not failure.
After relapse, individuals usually re-enter at contemplation or preparation with shorter latency, hence the “spiral” graphic showing incremental improvement toward long-term maintenance.
Widely adopted in drug/alcohol rehab, weight-loss programs, chronic-disease self-management workshops.

Unique to HBM: Perceived Threat (Susceptibility $+$ Severity).
Unique to TPB: Perceived Behavioral Control.
Shared elements:
- Cost–benefit calculus (HBM: Benefits & Barriers; TPB: Attitude).
- Social influence (HBM: Cues to Action; TPB: Subjective Norms).
Neither theory claims universal superiority; context matters:
- HBM shines for high-consequence health threats (e.g., cancer screenings).
- TPB excels when skill, resources, or self-efficacy are primary obstacles (e.g., regular exercise).

Practitioners quantify constructs via surveys → segment populations → tailor messaging.
Examples:
- Seatbelt PSAs: dramatize crash footage to raise perceived severity (HBM).
- Flu-shot reminders: leverage clinic texts as cues to action (HBM) and subjective norms (TPB).
- Community fitness challenges: boost perceived control by providing free gym access & coaching (TPB).
- Policy layer: improving produce availability in low-SES neighborhoods increases real & perceived control over healthy diet.

Zika-virus awareness campaign: citizens felt safe because they knew $0$ infected acquaintances; risk seemed abstract. Advocates decided to amplify threat perceptions → This aligns with Health Belief Model.
Exam question style: “Which model fits a case emphasizing susceptibility/severity?” → answer: HBM.
“Which model highlights self-efficacy/control?” → answer: TPB.

Memorize the unique constructs: Perceived Threat (HBM) vs. Perceived Control (TPB).
Use mnemonics:
- HBM → “H” for Hazard awareness (threat).
- TPB → “P” for Personal Power (control).
Link real-world examples to each construct; imagine designing your own PSA.
For TTM, visualize the spiral: relapse is expected; progress ≠ perfection.
When answering scenario questions:
1. Highlight clues (threat, control, intention, relapse).
2. Map them to the model’s vocabulary.
3. Eliminate distractors by spotting the unique term.
Ethical lens: fear appeals (HBM) must balance urgency with respect; excessive fear can stigmatize or paralyze. Empowerment (TPB) requires ensuring resources actually exist so perceived control reflects reality.