COM-B and the behaviour change wheel

The COM-B model sits in a larger framework known as the behaviour change wheel. An image of this is at the bottom of the page.

You can apply COM-B direct to an individual. But the key purpose is to apply it to intervention design as part of a broad approach.

The health and social care system is increasing its use of COM-B and the behaviour change wheel when developing interventions. It increases the chances for the intervention to succeed. 

The sections of the behaviour change wheel

Capability, opportunity and motivation are at the centre of the behaviour change process, as suggested by Susan Michie and colleagues.

The further you move from the centre of the wheel, the further you move away from the individual's influence on behaviour change. You then move into the intervention functions area and further still into policy influences on the ability for your behaviour to change.

So at the heart of the wheel are the sources of behaviour, which can be broken down further as shown:

• Capability (psychological and physical)
• Opportunity (social and physical)
• Motivation (automatic and reflective)

The second ring of the wheel features the intervention functions, which are:

• Restrictions
• Education
• Persuasion
• Incentivisation
• Coersion
• Training
• Enablement
• Modelling
• Environmental restructuring

The third and final ring of the wheel is policy categories, which are: 

• Environmental or social planning
• Communication or marketing
• Legislation
• Service provision
• Regulation
• Fiscal measures
• Guidelines

How COM-B elements interact

The purpose of COM-B is to establish the best approach to help you change a particular behaviour. You can do this as an individual or at an organisational level to support a patient or client.

The three key elements in COM-B (capability, opportunity and motivation) interact and influence each other. Interventions must target one or more of these to deliver and maintain effective behaviour change.

Capability and opportunity influence motivation. Not only do all three influence behaviour change but the change which occurs influences them.

For example, you may target the opportunity component to encourage someone who is inactive to be active. This could be by providing free group exercise sessions.

This person may have thought they did not have the appropriate skills to take part in an activity (capability). But as they got the opportunity to attend a class, by going they reinforced the idea they do have the capabilities required.