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Model

COM-B model

A model according to which any behavior needs three things at once: capability, opportunity and motivation.

In Spanish
Modelo COM-B
Origin
Michie, van Stralen and West (2011)

What problem it addresses

Helps diagnose why someone doesn't do something before deciding how to intervene. It was born in health psychology and is now also used in design.

Components

  • Capability

    Physical and psychological: knowing how and being able to do it.

  • Opportunity

    Physical and social: the environment and norms allow it.

  • Motivation

    Reflective and automatic: plans, but also habits and emotions.

An example

Imagine a hospital that wants staff to wash their hands more often.

Motivation onlycapabilitymotivationopportunity
The hallways fill up with posters about how important it is. They already knew.
COM-B diagnosiscapabilitymotivationopportunity
It turns out there are no dispensers next to the beds: what's missing is opportunity, not willingness. Dispensers are installed.

Diagnosing first avoids spending effort on the wrong barrier.

How it works

  1. Choose a specific behavior and ask what prevents it.

  2. Review each component: capability, opportunity and motivation.

  3. The intervention targets what is really missing.

Applications in design

  • Use it like this

    Before designing, note what is missing: do they know how and are they able to do it? Does the environment allow it? Do they want to do it?

  • Avoid

    Responding to everything with motivation campaigns when what is missing is capability or opportunity.

  • Don’t fall for it

    Observe people in their context: what they say does not always explain what they do.

Connections

Used in

Related to

Authors and works

  1. 2011

    Susan Michie, Maartje van Stralen and Robert West

    Proposed COM-B as the hub of the behavior change wheel, drawing on 19 earlier frameworks.

Sources

Original sources

Last reviewed: