Framework · Behavioral science
COM-B and the Behaviour Change Wheel
A behavior needs capability, opportunity and motivation, and each gap points to different fixes. Use it as a completeness check when diagnosing why a step leaks, especially to catch opportunity problems mistaken for knowledge problems. Moderate evidence as a diagnostic (B), less as an outcome predictor.
Plain label: capability, opportunity and motivation diagnosisAlso known as: COM-B, BCW, behaviour change wheel, BCT taxonomy
Core idea. Capability (physical and psychological), opportunity (physical and social) and motivation (reflective and automatic) must all be present. The wheel links each gap to intervention types such as education, persuasion, incentives, training, environmental restructuring, modeling and enablement. F06
Evidence. Evidence grade B. Moderate evidence: solid studies with some limits. Synthesized from 19 earlier frameworks and heavily used in health. Its authors note it has not been shown that wheel-designed interventions outperform others, so its value is diagnostic completeness.
How it plugs in. Pair it with B = MAP triage: Fogg's ability roughly equals capability plus physical opportunity, and the prompt is part of opportunity. The typical miss is shipping tutorials (education) for what is really an opportunity gap: the wrong moment, device or social context.
Sources
The behaviour change wheel: a new method for characterising and designing behaviour change interventions · Michie, van Stralen and West, Implementation Science 6:42, 2011
Evidence grade B. Moderate evidence: solid studies with some limits.A behavior model for persuasive design · Fogg, Persuasive 2009 (ACM), 2009
Evidence grade C. Limited evidence: few or small studies.
Source IDs: F06F01
Book content is paraphrased, never quoted at length. Last verified October 24, 2026.
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