Fogg Behaviour Model
Date: 2026-09-27
A behaviour happens when motivation, ability and a prompt are present at the same moment. Its use is diagnostic: when something isn’t happening, find which of the three is missing — and it’s usually ability, which is also the cheapest to fix.
The Fogg Behaviour Model states that a behaviour occurs when motivation, ability and a prompt converge at the same moment — written B = MAP.
Origin: BJ Fogg, Stanford Persuasive Technology Lab (now the Behavior Design Lab), first published at the Persuasive Technology conference in 2009; expanded in Tiny Habits (2019). Earlier versions called the prompt a “trigger”. It’s a design framework, not a tested causal model — no one measures motivation and ability on a common scale — so its value is as a checklist for diagnosis.
The shape
motivation
high │ ·
│ · ABOVE THE LINE
│ · prompt → behaviour
│ ·.
│ ·. ← action line
│ ·.
│ BELOW ··.
│ prompt fails ···.....
low │
└──────────────────────────── ability
hard to do easy to do
The curve is the point. High motivation tolerates hard tasks; easy tasks need very little motivation. A prompt only works above the line — below it, the prompt is noise, or worse, an irritant.
The three parts, in interface terms
| Element | On a site | Typical failure |
|---|---|---|
| Motivation | Wanting the outcome; trust; urgency that’s real | Unclear value, weak offer — The Offer |
| Ability | Time, money, effort, thought, fit with routine | Long forms, account walls, hidden costs, slow pages |
| Prompt | The button, the email, the notification, the reminder | Absent, mistimed, or arriving when ability is low (on mobile, mid-commute) |
Fogg’s six ability factors — time, money, physical effort, mental effort (brain cycles), social deviance, and non-routine — are a useful friction checklist in their own right. [CHECK: the exact list and naming in current Behavior Design Lab material.]
Using it to diagnose
SYMPTOM MISSING FIX FIRST
visitors reach the form, don't finish ability fewer fields, guest checkout
— Form Design, Checkout Design
high intent traffic, nobody clicks prompt a visible, specific CTA
emails opened, nothing happens ability deep link to the thing, not the homepage
people start trials, don't activate ability/prompt first step made trivial, timely nudge
nothing moves anyone motivation the offer, not the page
Ability before motivation. Raising motivation is hard, expensive and decays; removing a step is cheap and permanent. That’s the model’s most practical claim, and it matches most CRO experience — the reliable wins are friction removals, not persuasion — Cognitive Load, Form Design.
Prompts at the wrong moment train people to ignore them. A push notification when the person can’t act is a prompt below the action line — it spends attention and earns nothing, and repeated enough it becomes an unsubscribe — Lifecycle Messaging.
Prompt types
Fogg distinguishes three, by which element they lean on:
- Facilitator — for high motivation, low ability: makes it easier (“one tap to reorder”)
- Spark — for high ability, low motivation: adds a reason (“your points expire Friday” — only if they do)
- Signal — both are present; just a reminder (“your basket is saved”)
Mismatching the prompt to the gap is the usual failure — sending sparks (discounts) to people whose problem was ability (a broken checkout) teaches discount-dependence and doesn’t fix the checkout — Discounting Strategy.
Where it goes wrong
- Treating it as a formula. There are no units; B = MAP is a mnemonic
- Ignoring that it applies to single moments. It explains whether a tap happens now, not whether someone becomes a loyal customer
- Using ability to remove deliberation that should exist. One-click purchase of a subscription with hidden renewal terms makes ability high by hiding cost — Deceptive Design
- Motivation as a catch-all. “They weren’t motivated enough” explains everything and fixes nothing. Check ability and prompt first