Why People Do (or Don't) Act on Health Advice
The Health Belief Model (HBM), developed by Irwin Rosenstock, predicts that a person's decision to adopt a health behavior depends on their perception across several dimensions: perceived susceptibility (how at-risk they feel), perceived severity (how serious the consequences would be), perceived benefits (how much the action would actually help), and perceived barriers (the costs or obstacles involved). Two further components round out the model: self-efficacy (confidence in one's own ability to carry out the behavior) and cues to action (external triggers, like a symptom, a doctor's reminder, or a media campaign, that prompt the decision).
A related but distinct framework, Icek Ajzen's Theory of Planned Behavior (TPB), centers on intention as the direct predictor of behavior. Intention itself is shaped by three factors: attitude toward the behavior (is this a good idea?), subjective norms (what do people I care about think I should do?), and perceived behavioral control (how much control do I actually have over doing this?).
| Model | Key components |
|---|---|
| Health Belief Model | Susceptibility, severity, benefits, barriers, self-efficacy, cues to action |
| Theory of Planned Behavior | Attitude, subjective norms, perceived behavioral control → intention → behavior |
Both models converge on a similar practical lesson: simply telling someone a health behavior is beneficial rarely changes behavior on its own. Effective interventions typically also need to raise perceived susceptibility or severity, lower perceived barriers, build self-efficacy, or shift subjective norms — addressing the specific belief that is actually holding someone back.
Common pitfall: assuming perceived severity alone drives health behavior. A person can believe a disease is extremely severe and still not act, if they perceive themselves as not personally susceptible, or if perceived barriers (cost, time, discomfort) feel too high — the models require weighing several beliefs together, not just one.