The limits of COM-B and the Behaviour Change Wheel

The COM-B model and Behaviour Change Wheel (BCW) are widely used tools, but they’re not without their critics. Some argue that COM-B lacks predictive power, while others feel that the BCW is too broad to offer concrete guidance. In this post, we’ll address these objections and explore when these tools are most effective—and when you might need something more specific.

COM-B and the BCW are valuable for their flexibility and broad application, but like any tool, they’re not one-size-fits-all. Developed within implementation science, they’re designed to guide practical action in real-world settings. For precise predictions or complex behaviours, they’re best used in combination with other, more specific theories and models. Let's take a closer look at the objections!

Objection 1: Lack of predictive power in COM-B

One major critique of COM-B is that it lacks the predictive power of more established behavioural theories. Critics argue that while COM-B can help diagnose the factors that influence behaviour, it doesn’t provide specific predictions about how or why these factors interact to lead to behaviour change in a given context.

However, COM-B isn’t intended as a predictive theory but rather as a diagnostic model. Its primary strength lies in its simplicity and flexibility, which allows it to be applied across various behaviours and settings. Rather than offering complex predictions, COM-B provides a practical starting point to identify high-level barriers or enablers of behaviour (Capability, Opportunity, and Motivation). To make more precise predictions, COM-B works best alongside specific theories that offer a deeper understanding of psychological or social mechanisms.

COM-B doesn’t replace theory—it clarifies where to focus theoretical exploration. If your goal is to predict specific behaviours in controlled contexts (e.g., health interventions with fixed variables), using a specific theory from the outset may be more effective. While COM-B’s strength is its broad applicability, its weakness lies in predicting specific outcomes.

Objection 2: The BCW's lack of specificity and empirical backing

Critics of the Behaviour Change Wheel (BCW) argue that it is too broad and lacks empirical validation across diverse fields. Unlike theory-driven frameworks developed through extensive research in particular domains, the BCW serves as an organisational framework—pulling from multiple theories but offering less specificity and predictive accuracy.

While the BCW may not have the same empirical specificity as more traditional models, its strength lies in its comprehensiveness and practical application. It allows practitioners to integrate multiple theories and choose interventions based on diagnosed behaviour patterns (e.g., using COM-B and TDF). This makes it a valuable tool in real-world settings where practitioners need a systematic approach to selecting strategies without relying on a single theory.

The empirical base for the BCW is growing, with research studies showing its effectiveness in areas like public health and policy interventions. However, more comparative studies are needed to fully establish its strengths and limitations compared to other well-established frameworks.

For contexts requiring highly controlled, theory-specific predictions, the BCW might not be the best option. In such cases, using a single predictive theory with a stronger research base may provide more precision, but for interventions that need flexibility across contexts, the BCW’s structured approach offers practical guidance.

Objection 3: COM-B and BCW lack granularity for complex behaviour

Another critique is that COM-B and BCW are too simplistic to address complex behaviours or interventions involving multiple layers of interaction (e.g., social, environmental, organisational influences). Critics argue that by focusing on broad categories like Capability, Opportunity, and Motivation, COM-B oversimplifies human behaviour and doesn’t account for nuanced factors like emotions, habits, power dynamics, or social networks.

It’s true that COM-B and the BCW operate at a high level, but they are intended to be starting points for behaviour diagnosis and intervention design. These tools are broad by design to allow flexibility across different contexts. However, they can be augmented by more specific models or theories to address deeper layers of behaviour. The Theoretical Domains Framework (TDF) offers granularity when needed, breaking down broad categories into 14 specific domains, which allows practitioners to move beyond the simplicity of COM-B for more complex interventions.

In complex, multi-layered interventions, using multiple models and theories together helps capture the full range of behavioural influences. COM-B and BCW provide useful entry points but work best when integrated with more complex theories and frameworks.

When to use COM-B and BCW, and when to consider alternatives

COM-B and the Behaviour Change Wheel are valuable tools when used appropriately, but like any approach, they have their limitations. They are most effective when:

• The goal is to identify broad drivers of behaviour quickly.

• Practitioners need a flexible and adaptable approach across various settings.

• The intervention context is dynamic and requires a framework that pulls from multiple theories.

  
  

However, if you need highly specific predictions or are working in a tightly controlled environment, more predictive theories might offer the specificity required.

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This post is an additional part of my "Making Sense of Behaviour Change" series, which explores how tools like theories, models, and frameworks guide the process from diagnosis to intervention design. Check out Part 1 for an introduction: Understanding how theories, models, and frameworks complement each other