Comparing Fogg Behavior Model and COM-B

When it comes to changing behaviour, there are models designed for quick results and others built for sustainability. Fogg’s Behaviour Model (FBM) offers a straightforward approach: focus on simplicity and immediate triggers to prompt action. Meanwhile, COM-B takes a broader view, considering the deeper factors—Capability, Opportunity, and Motivation—that underpin lasting change.

In this follow-up article to an earlier post on the details of the Fogg Behaviour Model (B-MAP), I’ll unpack how each model approaches Ability, Motivation, and Prompts, and examine why the gap between a quick nudge and lasting change goes deeper than just timing. If you're in a hurry, I've included a quick snapshot in the image - click to enlarge for where this article is going before diving into the full analysis.

N.B. This is just my perspective—everyone is welcome to do their own analysis based on publicly available materials. Critique of ideas is a crucial part of scientific discourse, and my aim here is to share my own evaluation. Scientific models can evolve, and discussion helps refine them.

TL;DR - If you're designing apps or other persuasive technology, FBM may well work for you - that's not the kind of work I do, so there's nothing FBM can do that COM-B/BCW can't do much more robustly and comprehensively.

Ability vs Capability

In COM-B, Capability refers to whether a person has the underlying knowledge, skills, and physical capacity to perform a behaviour, not just in the immediate moment but over time. This includes aspects like physical skills, cognitive abilities, and self-regulation, and these factors can often be developed through training or education. It’s not about making the behaviour simpler in the moment but ensuring that the person is fundamentally capable of carrying it out.

Fogg's Ability, however, focuses on simplicity—removing friction to make the behaviour easy to perform right now. It addresses immediate barriers, such as time or effort, rather than whether a person is equipped with the necessary skills or knowledge to perform the behaviour in the first place.

While FBM is effective for designing systems that reduce friction in the short term, COM-B provides a more comprehensive view by considering both the immediate and long-term capability of the person, making it suitable for interventions that require skills development or behavioural regulation.

In COM-B, Capability encompasses a person's physical and psychological capacity to perform a behaviour. It refers to whether someone fundamentally has the necessary skills, knowledge, and mental or physical attributes to carry out the behaviour, either immediately or over the long term. Capability goes beyond the momentary ease of performing a task and involves considering whether someone is equipped to develop and sustain the behaviour.

The Theoretical Domains Framework (TDF), which underpins the COM-B model, provides a detailed breakdown of what is included in capability. This includes:

• Knowledge: Understanding how to perform the behaviour and why it is important.

• Cognitive skills: Memory, decision-making, and the ability to focus on the behaviour.

• Physical skills: Whether the person has the physical strength, dexterity, or stamina required for the task.

• Behavioural regulation: The person's ability to monitor and adapt their own behaviour over time.

  
  

In Fogg's Behaviour Model (FBM), Ability is broken down into six elements: time, money, physical effort, brain cycles, social deviance, and routine. These factors are very context-specific and focus on making a behaviour simple and easy to perform in the moment. However, these elements cover more than what is described in Capability within COM-B; some of them fall under Opportunity in COM-B as well.

Key Differences

1. Immediate ease vs foundational capacity: Fogg’s ability is about making behaviour simple by reducing barriers in the present moment. Capability in COM-B, however, looks at whether someone has the knowledge and skills to perform the behaviour now and in future situations. It’s a more holistic view of the person’s ability to engage in the behaviour, considering both immediate and long-term capacity.

2. Simplicity vs skills development: In FBM, ability is increased by simplifying the behaviour, removing complexity through design. In COM-B, improving capability often means building the person's knowledge or skills through training, education, or support. It’s not about simplifying the task but ensuring the person is equipped to perform it.

3. Short-term vs long-term focus: FBM focuses on creating conditions where a behaviour is easy right now (e.g., one-click ordering). COM-B considers the person's underlying capability, which may require long-term development (e.g., learning to manage a chronic condition).While FBM is effective for designing systems that reduce friction in the short term, COM-B provides a more comprehensive view by considering both the immediate and long-term capability of the person, making it suitable for interventions that require skills development or behavioural regulation.

   
   

Overlaps with COM-B Dimensions

Time and Money

• FBM (Ability): Time and money are considered resources that can either simplify or complicate the ability to perform a behaviour. Fogg focuses on the immediate availability of these resources to make a behaviour easier or more difficult to execute in the moment.

• COM-B (Opportunity): Time and money are seen as external factors in the environment that can enable or hinder behaviour. Even if a person has the capability and motivation, lack of time or financial resources can prevent them from performing the behaviour.

Physical Effort

• FBM (Ability): Physical effort is tied to the immediate ease or difficulty of performing a behaviour. Fogg treats effort as a barrier to be minimised, focusing on making behaviours as effortless as possible in the present context.

• COM-B (Capability): Physical Capability includes the person's overall physical strength, stamina, or dexterity to perform the behaviour. COM-B asks whether the person has the physical skills to perform the behaviour at all, which can be addressed through training or physical development.

Brain Cycles

• FBM (Ability): Brain cycles refer to the cognitive load or mental effort required to perform the behaviour. Fogg focuses on reducing cognitive complexity to make behaviours easier to perform.

• COM-B (Psychological Capability): Psychological Capability refers to whether a person has the mental skills, knowledge, and cognitive resources to perform the behaviour. COM-B addresses whether someone is equipped cognitively and mentally to perform the behaviour.

Social Deviance

• FBM (Ability): Social deviance is treated as a barrier to ability—something that makes a behaviour harder because it goes against social norms. Fogg focuses on the immediate social context and how it can hinder or facilitate a behaviour.

• COM-B (Social Opportunity): Social Opportunity refers to social influences, including norms and cultural expectations, that affect whether a behaviour is performed. If a behaviour requires going against these norms, the social environment becomes a barrier, making it a lack of opportunity rather than a lack of capability.

Non-Routine

• FBM (Ability): Non-routine behaviours are considered harder to perform because people prefer sticking to familiar patterns. Fogg focuses on the immediate difficulty of performing behaviours that are not part of established routines.

• COM-B (Opportunity/Capability): Non-routine behaviours link both to Capability (the skills and cognitive ability to perform new behaviours) and Opportunity (the environment that supports or resists change in routines). In COM-B, if a behaviour is non-routine, you might need to develop the person’s capability through repeated practice, or change the environment to support new routines. d creating an environment that supports the new routine.

Examples and comparison table at the end of the article.

Motivation

Fogg’s model simplifies motivation by focusing on immediate emotional responses that push for quick action, often relying on social acceptance/rejection and other emotional levers.

COM-B, on the other hand, breaks motivation into two key categories—Reflective and Automatic—which provide a more comprehensive understanding of both short-term and long-term drivers of behaviour. This split allows for a more tailored approach to behaviour change, addressing both conscious planning and habit formation.

In COM-B, Motivation is divided into two distinct components: Reflective Motivation and Automatic Motivation. This distinction captures both the conscious, rational decision-making processes and the habitual, emotional drivers that influence behaviour. Reflective motivation involves setting goals, making deliberate choices, and using self-regulation, while automatic motivation includes impulses, emotions, and ingrained habits that are often triggered by environmental cues. Together, these two aspects provide a comprehensive view of what drives behaviour over both the short and long term.

• Reflective Motivation: This is the conscious, goal-oriented aspect of motivation. It involves deliberate thought, planning, and decision-making. People engage in behaviour because they believe it aligns with their long-term goals, values, or beliefs.

• Automatic Motivation: This is emotionally driven and involves habitual responses that require little conscious thought. Automatic motivation is often influenced by emotional states, impulses, and the cues that exist in a person's environment, which can trigger habitual behaviours.

In Fogg’s model, motivation is driven by immediate emotional drivers:

• Pleasure/pain: Whether the behaviour leads to immediate pleasure or avoids discomfort.

• Hope/fear: Positive or negative future outcomes, such as excitement about a potential reward or fear of missing out (FOMO).

• Social acceptance/rejection: The desire for social inclusion or fear of being excluded, which often serves as a powerful motivator in social contexts.

These motivators are designed to create an emotional response that either encourages the person to act (by promising a reward or avoiding a loss) or discourages them from acting (by highlighting negative consequences). This approach is focused on short-term behaviour activation by tapping into the most immediate emotional responses a person experiences.

In short, Fogg’s motivation is about creating strong enough emotional or social triggers to drive immediate action. The emphasis is on leveraging a person's emotions—whether that's excitement about a reward, fear of missing out, or the desire to fit in socially—to prompt behaviour right now, with less concern for long-term or reflective decision-making.

Key Differences

1. Reflective vs Emotional Motivation:

   • In COM-B, Reflective Motivation focuses on long-term goals, conscious decision-making, and planning. It’s about helping people align their behaviour with their values or aspirations through deliberate thought and self-regulation.

   • In FBM, Motivation is driven by immediate emotional responses like pleasure, pain, hope, fear, and social pressure. The focus is on short-term emotional triggers that can spark immediate action.

2. Automatic vs Habitual Responses:

   • Automatic Motivation in COM-B deals with habits, impulses, and ingrained behaviours that require little conscious thought. These automatic responses are often triggered by environmental or emotional cues and can either support or hinder behaviour change.

   • In FBM, automatic and habitual responses aren’t explicitly broken down, but the emphasis on social acceptance/rejection and emotional triggers indirectly touches on similar ideas, with a strong focus on external factors like social norms and immediate emotional states.

3. Short-term vs Long-term Focus:

   • FBM emphasises short-term motivational drivers, focusing on getting people to act immediately based on their emotional responses. The goal is often to create a sense of urgency, leveraging emotions like fear of missing out or excitement over a reward.

   • COM-B takes a more comprehensive view, addressing both immediate motivators (automatic motivation) and long-term, goal-driven motivators (reflective motivation). This allows for interventions that can both prompt short-term behaviour and sustain it over time by building motivation through planning and habit formation.On the surface, someone might equate Fogg’s Motivation with COM-B’s Automatic Motivation, since both deal with emotional and automatic responses. However, there are critical differences in focus and application:

• Fogg's Motivation is about immediate emotional drivers, such as pleasure, pain, hope, fear, and social acceptance/rejection, used to trigger behaviour right now. These are often situational and short-term, relying on external emotional pressures.

• COM-B’s Automatic Motivation, on the other hand, is about habitual behaviours and emotion-driven responses that can be triggered by the environment. It looks at both short- and long-term automatic responses and how they sustain or hinder behaviour without conscious reflection.

In other words, Automatic Motivation in COM-B isn’t just about immediate emotional triggers (like in Fogg), but about long-term behaviour change and emotional cues that sustain behaviour over time.

Prompts in Fogg's FBM vs Opportunity in COM-B

Prompt in Fogg's model is much closer to a Behaviour Change Technique (BCT) than a structural factor like Opportunity in COM-B. In fact, prompts are explicitly listed as a BCT in the Behaviour Change Techniques Taxonomy (BCTTv1), where they are referred to as “cues” or “reminders” designed to trigger behaviour. This distinction is critical for a few reasons, and understanding it helps clarify the relationship between the two models - and there are consequences for getting things mixed up.

In short, Fogg’s Prompts are BCTs that initiate behaviour by nudging someone in the moment. They activate behaviour, but they don’t change the context or remove long-term barriers. COM-B’s Opportunity is about ensuring the environment supports behaviour change. Prompts might be one of many techniques used to tackle opportunity barriers, but opportunity requires structural interventions (like providing resources or changing social norms) that go beyond a simple nudge.

Key Differences:

1. Specific trigger vs environmental conditions:

   • A prompt in Fogg’s model is a specific action that triggers behaviour (e.g., a reminder or alert). It’s an external, situational cue that prompts someone to act at that moment.

   • Opportunity in COM-B, on the other hand, is about the broader environment that either supports or limits behaviour. It’s not just about a momentary trigger, but about whether the surrounding context (both physical and social) is conducive to the behaviour happening.

2. Immediate vs contextual:

   • Fogg's Prompts are immediate. They happen in the moment and drive action quickly, often within seconds or minutes.

   • COM-B's Opportunity includes longer-term, broader conditions like access to resources, social support, or cultural norms. These aren’t triggers per se, but they create the conditions that make behaviour possible or likely.

3. Short-term vs long-term influence:

   • A Prompt is effective for short-term action—it triggers behaviour when it’s needed.

   • Opportunity can affect behaviour in the long term by shaping the environment and the context in which the behaviour is performed.

Consequences of Considering Prompts as BCTs:

A prompt is an intervention tactic, while opportunity is an underlying condition or barrier that might require multiple techniques (including prompts) to address.

• Fogg’s Prompt is a tool used to spark behaviour; it's a specific technique that falls within an intervention to remind or nudge someone.

• COM-B's Opportunity, on the other hand, is a broader contextual factor that addresses the overall environment in which behaviour occurs. Opportunity refers to whether the person has the external conditions (physical and social) needed to perform the behaviour in the first place, not just a momentary nudge to do so.

Prompts are just one possible technique within a larger intervention designed to address environmental barriers identified through COM-B’s Opportunity.

• Fogg’s Prompt is about tactical intervention: a tool you use to activate behaviour once motivation and ability are aligned. Prompts are effective for creating quick responses but don’t necessarily address why the behaviour isn’t occurring if other barriers are present (e.g., lack of opportunity or motivation).

• COM-B’s Opportunity looks at why the behaviour is not happening in the first place: it examines structural barriers, like whether the environment supports the behaviour. This might involve changing physical access (like providing resources) or modifying social norms (like creating a supportive community).

A prompt helps start a behaviour but won’t necessarily help sustain it. Opportunity looks at creating the conditions where the behaviour can be repeated and embedded into daily life.

• Fogg’s Prompt is aimed at immediate behaviour activation, focusing on initiating action in the short term (e.g., “check your app now”).

• Opportunity in COM-B influences whether a person can maintain the behaviour over time. It’s about setting up conditions that support long-term behaviour change (e.g., having ongoing access to resources or social support).

Example of the Consequences:

Let’s say we want to get someone to exercise regularly:

• Fogg's Prompt: You could use a notification on their phone reminding them to go for a run. This might trigger immediate action, but if they don't have time, a safe space to exercise, or social support, the prompt will likely fail to lead to sustained behaviour.

• COM-B's Opportunity: To ensure sustained exercise behaviour, you would need to address physical opportunity (e.g., having access to a gym or safe running paths) and social opportunity (e.g., joining a running group or having encouragement from friends). Prompts could be part of the intervention (e.g., reminders to run), but they alone wouldn’t be enough to tackle all the external barriers.

Fogg’s model is action-oriented: prompts are excellent tools for triggering behaviour when both motivation and ability are already aligned. However, without addressing structural barriers, these prompts might fail to produce consistent, long-term behaviour change. COM-B offers a broader framework: it suggests that to change behaviour effectively, we must address capability, opportunity, and motivation. Prompts (as BCTs) are useful within this framework but need to be combined with efforts to modify the environment and provide ongoing social and physical support.

In short, Prompts are closer to BCTs, making them one possible tool for behaviour activation, while Opportunity in COM-B is a broader structural factor that might require several techniques, including prompts, to be addressed.

Wrapping up the Behaviour Battle

When it comes to behaviour change, Fogg and COM-B take very different approaches—one prioritises quick wins, while the other builds for the long haul.

Fogg’s model is like fast food—quick and convenient, relying on simplicity and immediate emotional triggers like prompts to drive action in the moment. It satisfies an immediate need, but like fast food, it isn’t designed to nourish behaviour over the long term. While Fogg’s approach makes behaviour easy and tempting in the short run, it doesn’t address the deeper elements needed to sustain that behaviour once the initial spark wears off.

By contrast, COM-B is the thoughtful chef preparing a nutritious meal, carefully balancing the essential ingredients—Capability, Opportunity, and Motivation—to support behaviour change not just for today, but for the future as well. With its integration of the Theoretical Domains Framework (TDF), COM-B digs deeper into the complex interplay of internal skills, external resources, and the triggers that drive long-term action.

In the end, behaviour change isn’t just about getting people to act once—it’s about creating the conditions that make that behaviour stick. Fogg may get you through the door, but COM-B ensures you stay in the game for the long run.

---

Appendix:

Examples of Fogg's Ability

Time and Money

• FBM (Ability): Having enough money to buy a product right now makes the purchasing behaviour easier.

• COM-B (Opportunity): Not having enough time to exercise due to work commitments can hinder the behaviour, regardless of the person's motivation or physical capability.

Physical Effort

• FBM (Ability): Making a product easy to access or use reduces the physical effort required, increasing the likelihood of the behaviour.

• COM-B (Capability): A person may need to build stamina through training to be capable of running a marathon.

Brain Cycles

• FBM (Ability): Simplifying a sign-up process reduces the mental effort required, making it more likely that users will complete the process.

• COM-B (Psychological Capability): A person may need to acquire knowledge and skills through education to be capable of performing complex tasks at work.

Social Deviance

• FBM (Ability): A behaviour that is not socially accepted may be harder to perform due to fear of judgement.

• COM-B (Social Opportunity): Social norms that discourage certain behaviours can hinder their performance, even if the person is physically and mentally capable.

Non-Routine

• FBM (Ability): Introducing a new behaviour that is not part of a person's routine can be challenging due to the lack of familiarity.

• COM-B (Opportunity/Capability): Establishing a new exercise routine may require developing the capability to perform the exercises and creating an environment that supports the new routine.

	Fogg Behaviour Model (FBM)	COM-B
Time & Money	Resources that simplify or complicate action	Opportunity: External factors enabling or hindering behaviour.
Physical Effort	Immediate difficulty of performing behavior.	Capability: Overall physical strength, stamina, or dexterity. Physical Opportunity: things in the physical environment that influence behaviour
Brain Cycles	Cognitive load or mental effort required.	Psychological Capability: Mental skills, knowledge, and cognitive resources to perform behaviour.
Social Deviance	Barrier due to going against social norms.	Social Opportunity: Social influences, norms, and cultural expectations affecting behaviour.
Non-Routine	Difficulty due to unfamiliarity	Opportunity/Capability: Need for skill development or environmental support for new behaviours.

	Fogg's Ability	COM-B's Capability
Focus and use	Short-term behaviour design: ease of performing behaviour in specific context;	Foundational capacity, skills development, behavioural regulation and long-term development;
Key factors	Time, money, physical effort, brain cycles, social deviance, routine.	Physical skills, strength/stamina, knowledge, cognitive skills,behavioral regulation.
Timeframe	Short-term view: Is the behaviour easy to perform right now?	Short and long-term: Can the person perform the behaviour now and in the future?
Illustration of assumptions and approach	Humans prefer ease so we should reduce complexity and friction through design (e.g., Amazon's 1-click shopping).	People can learn and develop skills over time. so we should build capacity through learning, training, or experience
Example application	One-click ordering	Learning to manage a chronic condition
Core difference	Make behavior as easy as possible right now.	Build capacity to perform behavior, regardless of immediate barriers

	Fogg's Prompt (BCT)	COM-B's Opportunity
Focus and use	Specific intervention technique to trigger behaviour in the moment (e.g., reminders, notifications).	Long-term motivation driven by conscious planning and goals. Focuses on goal-setting, intentions, and self-regulation.
Key factors	Pleasure/pain, hope/fear, social acceptance/rejection.	Conscious decision-making, planning, and goal-setting.
Timeframe	Short-term: motivating someone to act immediately through emotional or social triggers.	Long-term: motivation driven by rational, goal-directed behaviour.
Illustration of assumptions and approach	Assumes behaviour is driven by immediate emotional rewards or social pressures. Focuses on creating urgency or social pressure to drive action.	Assumes behaviour is driven by deliberate goals and intentions. Focuses on supporting goal-setting, self-monitoring, and planning.
Example application	Using a countdown timer or a limited-time offer to create urgency and fear of missing out, thereby motivating someone to make a purchase immediately.	Setting a long-term goal like saving for retirement or training for a marathon, supported by regular monitoring.
Core difference	Focuses on short-term emotional triggers, often driven by social or emotional factors like fear of missing out.	Focuses on long-term goal-setting and deliberate action, driven by conscious planning and rational thought.

	Fogg's Motivation	Reflective Motivation	Automatic Motivation
Focus and use	Immediate, emotional motivators. Primarily focused on short-term action.	Long-term motivation driven by conscious planning and goals. Focuses on goal-setting, intentions, and self-regulation.	Habitual, emotional responses and environmental cues that trigger automatic behaviour. Short-term focus but can sustain behaviour over time.
Key factors	Pleasure/pain, hope/fear, social acceptance/rejection.	Conscious decision-making, planning, and goal-setting.	Habits, emotions, environmental cues.
Timeframe	Short-term: motivating someone to act immediately through emotional or social triggers.	Long-term: motivation driven by rational, goal-directed behaviour.	Both short-term and long-term: sustained by habits, emotional responses, and environmental reinforcement.
Illustration of assumptions and approach	Assumes behaviour is driven by immediate emotional rewards or social pressures. Focuses on creating urgency or social pressure to drive action.	Assumes behaviour is driven by deliberate goals and intentions. Focuses on supporting goal-setting, self-monitoring, and planning.	Assumes behaviour is driven by emotional impulses and habits. Focuses on reinforcing positive habits and automatic responses.
Example application	Using a countdown timer or a limited-time offer to create urgency and fear of missing out, thereby motivating someone to make a purchase immediately.	Setting a long-term goal like saving for retirement or training for a marathon, supported by regular monitoring.	Establishing habits like drinking water first thing in the morning or checking a health app daily, triggered by cues like time of day or environmental prompts.
Core difference	Focuses on short-term emotional triggers, often driven by social or emotional factors like fear of missing out.	Focuses on long-term goal-setting and deliberate action, driven by conscious planning and rational thought.	Focuses on automatic, habitual behaviours triggered by emotional or environmental cues, sustaining behaviour without continuous emotional triggers.