Stanford researcher BJ Fogg proposed a simple, useful model for when a behavior actually happens: B = MAP — Behavior occurs when Motivation, Ability, and a Prompt all converge at the same moment. Miss any one of the three, and the behavior doesn't happen, no matter how well-designed the rest of the experience is.
| Element | What it means | Example |
|---|---|---|
| Motivation | How much the person wants to do it right now | Wanting to save money vs. not caring today |
| Ability | How easy the action actually is to do | A one-tap checkout vs. a 12-field form |
| Prompt | Something that triggers the action at the right moment | A notification, a visible button, a reminder email |
The model's real value is diagnostic — when users aren't doing something a product wants them to do, the model asks which of the three is actually missing. A designer's instinct is often to add more motivation (bigger call-to-action, more persuasive copy), but the real problem is frequently ability — the action is simply too hard, and no amount of motivational copy fixes that. Fogg's own advice: when in doubt, make it easier before trying to make people want it more.
Fogg also classifies behaviors along two axes: whether the behavior is new or existing, and whether it's meant to happen once, for a period, or forever (as a habit). A one-time signup and a daily habit loop are fundamentally different design problems — the grid is a quick check on which one is actually being designed for before reaching for a specific technique.
The most common mistake this model catches
Before adding another motivational nudge to a struggling flow, ask honestly: is this actually an ability problem in disguise? Reducing steps usually beats adding persuasion.