You launched the new expenses tool, ran the training, sent the email. Three weeks later half the team is still snapping photos of receipts and emailing them to finance. The instinct is to conclude people are lazy or resistant. The behavioural design literature offers a more useful read: a behaviour didn't happen because one of its ingredients was missing, and you can usually name which one.

The quick version

  • Fogg's B=MAP says a behaviour needs three things at once, motivation, ability and a prompt. No prompt, no behaviour, however keen people are.
  • COM-B (from health psychology) widens "ability" into capability and opportunity, the environment and social setting also have to allow the behaviour.
  • The Hook Model chains trigger → action → variable reward → investment to build a habit, not just a one-off action.
  • The honest move in all three: when adoption stalls, cut friction and fix the prompt before you try to boost motivation, motivation is the least reliable lever you have.

The idea in depth

"Behavioural design" is just the discipline of arranging conditions so a desired behaviour becomes more likely, and arranging them deliberately, rather than hoping a memo does the work. Three models dominate the field. They overlap, they disagree at the edges, and a leader who knows all three can diagnose a stalled rollout in about five minutes.

Fogg's Behavior Model: B = MAP

BJ Fogg, who directs the Behavior Design Lab at Stanford, compresses behaviour into one line: Behavior happens when Motivation, Ability and a Prompt come together at the same moment (behaviormodel.org). He writes it B = MAP. Drop any one of the three and the behaviour doesn't occur, which is why "B=MAP" and "the Fogg Behavior Model" are the same thing, not two separate models. (You'll sometimes see it written "BMAP"; same formula.)

The part most leaders get wrong is the trade-off between motivation and ability. Fogg's "action line" curves: when a behaviour is very easy, almost no motivation is needed to trigger it; when it's hard, you need a lot. His repeated, counter-intuitive claim is that ability, not motivation, is usually the bottleneck. People generally want to file the expense; they just can't face fourteen fields and a login at 6pm. Motivation is real but volatile, so the reliable lever is making the action smaller.

The third element, the prompt, is the one teams forget entirely. Fogg distinguishes three kinds: a spark (motivates someone who's able but unwilling), a facilitator (makes things easier for someone willing but unable), and a signal (a plain reminder for someone both willing and able). Match the prompt to the gap, sending a motivating pep-talk to someone who's simply stuck is the wrong prompt for the wrong problem.

So the move is: before you launch a behaviour-change push, write down all three ingredients and find the weakest. If ability is low, shrink the task (pre-fill fields, remove a login, cut steps). If a prompt is missing, add one at the moment of highest ability, not a generic Monday email, but a cue at the point of action.

Where it breaks down: the model is a lens, not a measured law. It doesn't tell you how much motivation a given behaviour needs, and it treats "ability" as a property of the person and the task, which understates how much the surrounding environment decides what's even possible. That gap is exactly what the next model fills.

flowchart LR
    M("Motivation
do they want to?")
    A("Ability
is it easy enough?")
    P("Prompt
were they cued, now?")
    B(["Behaviour happens"])
    M --> B
    A --> B
    P --> B
    note("All three must
land at the same moment")
    note -.-> B
Fogg's B=MAP: motivation, ability and a prompt have to converge at one moment. Leaders Loop

COM-B: behaviour as capability, opportunity and motivation

The COM-B model comes from health psychology, where the stakes (getting people to take medication, wash hands, stop smoking) made wishful thinking expensive. Susan Michie, Maartje van Stralen and Robert West set it out in Implementation Science in 2011 ("The behaviour change wheel: a new method for characterising and designing behaviour change interventions", vol. 6, art. 42). Their claim is that behaviour (B) is generated by three interacting conditions: Capability, Opportunity and Motivation.

The move that makes COM-B more powerful than Fogg's model for organisations is Opportunity. Michie and colleagues define it as the factors that lie outside the individual and make a behaviour possible or prompt it, split into physical opportunity (does the environment, the tooling, the time allow it?) and social opportunity (does the culture make it normal?). Capability is similarly split into psychological (knowledge, skill) and physical. In other words, COM-B refuses to let you blame the person before you've checked the system around them.

"Opportunity" is the factors outside the individual that make a behaviour possible, the part leaders control and most often ignore.

What this buys you in practice: run the stalled behaviour through six boxes, not one. Do people know how (psychological capability) and are they physically able? Does the environment let them, time, access, tools (physical opportunity), and do they see peers and managers doing it (social opportunity)? Is there real drive, habitual and emotional, not just stated intent (motivation)? Whichever box comes up empty is your intervention. Most "training problems" turn out to be opportunity problems: people knew how, the system just didn't allow it.

Where it breaks down: COM-B is thorough but not predictive, it's a checklist for diagnosis, not a formula that tells you which lever will move the needle most, or by how much. West and Michie's own 2020 reappraisal of the model (titled, fittingly, "Properties, Problems and Prospects") works through its open questions; treat it as a structured way to ask the right questions, then test, rather than a settled science of change.

flowchart TB
    C(["Capability
knowledge, skill,
physical capacity"])
    O(["Opportunity
environment, tools,
time, social norms"])
    Mo(["Motivation
reflective intent +
habit & emotion"])
    B(["Behaviour"])
    C --> B
    O --> B
    Mo --> B
    C --- O
    O --- Mo
    Mo --- C
COM-B: the three conditions interact, strengthen one and you can shift the others. Leaders Loop

The Hook Model: from one action to a habit

Fogg and COM-B explain a single behaviour. Nir Eyal's Hook Model, from his 2014 book Hooked: How to Build Habit-Forming Products, explains how you turn a behaviour into a recurring one. It runs as a four-stage loop: Trigger → Action → Variable Reward → Investment. The trigger cues the behaviour (and over time an internal trigger, boredom, anxiety, replaces the external one). The action is the simplest behaviour in anticipation of reward (Eyal builds directly on Fogg here: make it easy). The variable reward, unpredictable, like B.F. Skinner's intermittent reinforcement, is what keeps people coming back. And the investment is a bit of effort or data the user puts in that makes the product better next time and pulls them back into the loop.

The move here is different: if you want a behaviour to stick rather than spike, design the loop, not the launch. After someone does the action, give a reward worth returning for and ask for a small investment that compounds, a saved preference, a populated profile, a logged entry. A tool people configure is a tool people come back to.

Where it breaks down, and this one matters: the Hook Model is ethically loaded. The same loop that builds a useful habit builds a compulsive one, and Eyal knows it, his own "manipulation matrix" asks two blunt questions before you build: does this materially improve the user's life, and would the maker use it themselves? Answer no to both and you're not designing, you're exploiting. For an internal tool the test is simpler still: are you helping people do work they want to do, or engineering compulsion around work they resent? Use the loop on behaviours that genuinely serve the person, or don't use it.

A worked example

A regional services firm, illustrative, not a real client, rolls out a new CRM and mandates that reps log every client call. Eight weeks in, logging sits at roughly 40% (an illustrative figure). Leadership's first reaction: reps don't value data. The behavioural read is different.

Run it through COM-B. Capability: reps were trained, they know how, capability isn't the gap. Opportunity: logging requires opening a laptop, finding the client, and filling nine fields, but most calls happen from a car between visits. Physical opportunity is near zero at the moment the behaviour should occur. Motivation: reps see logging as admin that helps head office, not them.

Now Fogg. The behaviour needs ability at the moment of the call, and a prompt then too, both missing. The fix isn't a motivational all-hands. It's a 20-second mobile log (three fields, voice-to-text for notes), a facilitator prompt that fires from the calendar entry the instant a meeting ends. Ability up, prompt placed at peak opportunity.

Then the Hook layer, used honestly: the reward is that each logged call auto-builds a client timeline the rep actually uses to prep the next visit, a variable, genuinely useful payoff. The logging is the investment, and it compounds into a better tool for the rep, not just a fuller database for head office. Logging climbs because the behaviour finally serves the person doing it. No one's character changed; the conditions did.

Frequently asked questions

What's the difference between the Fogg Behavior Model and COM-B?

Fogg's B=MAP names three ingredients of a single behaviour at a single moment, motivation, ability, prompt, and is built for designing prompts and reducing friction. COM-B, from Michie, van Stralen and West (2011), covers similar ground but splits "ability" into capability and opportunity, making the external environment and social norms first-class factors. Fogg is sharper for product and prompt design; COM-B is broader for diagnosing why a whole organisation isn't doing something.

Is "BMAP" a separate model from the Fogg Behavior Model?

No. "BMAP" (or B=MAP) is simply how Fogg writes his formula, Behaviour = Motivation, Ability, Prompt. If you see it listed alongside "the Fogg model" as though they were two things, that's a labelling slip, not two frameworks.

Is the Hook Model just a polite word for manipulation?

It can be, which is why Eyal pairs it with an ethics test. The loop is morally neutral machinery; the question is what behaviour you're reinforcing. Applied to behaviours that genuinely benefit the person, fitness, learning, useful work tools, it's good design. Applied to behaviours that profit you at the user's expense, it's the dark pattern people rightly distrust. The honest filter: would you be comfortable if the user saw exactly how the loop was built?

Which model should I reach for first?

Diagnose with COM-B (its six boxes catch the most failure modes), redesign the specific behaviour with Fogg's B=MAP (it tells you precisely what to make easier and when to prompt), and only reach for the Hook Model when you want a one-off action to become a recurring habit, and only when the habit serves the person, not just the organisation.

Do these work for changing my own behaviour, not just other people's?

Yes, Fogg's own Tiny Habits (2019) is the self-directed version: shrink the behaviour until it's almost too easy to fail, and anchor it to an existing prompt in your day. The same "lower the ability bar, fix the prompt" logic applies whether the behaviour is yours or your team's.

Related in the Toolkit

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