Fogg Behavior Model

Understanding Behavior Change: B = M × A × P

B = M × A × P

Behavior = Motivation × Ability × Prompt

The Behavior Model Graph

Action Line
Current State

Adjust Parameters

50
How much do you want to do this behavior?
50
How easy is it to do this behavior?
Time
Money
Physical Effort
Mental Effort
Routine
Social Deviance
50
Is there a effective trigger/cue?

Behavior Prediction

🤔

Behavior Uncertain

Adjust the parameters to see if the behavior will occur.

B = 50 × 50 × 50 = 125000
Action line threshold (Motivation ≥)

The Three Core Elements

🔥

Motivation

The desire to perform the behavior. Includes pleasure/pain, hope/fear, and social acceptance/rejection.

Stability: Low (Fluctuates)

Ability

The ease of performing the behavior. Affected by time, money, physical effort, mental effort, routine, and social deviance.

Stability: High (Stable)
🔔

Prompt

The trigger that cues the behavior. Can be a spark, facilitator, or signal depending on the context.

Stability: Variable

Types of Prompts

High Ability, Low Motivation

Spark

Ignites motivation when ability is high but motivation is low. Uses emotion, stories, and incentives.

Example: Emotional ad, limited-time offer
Low Ability, High Motivation

Facilitator

Makes behavior easier when motivation is high but ability is low. Provides guidance, templates, and simplification.

Example: Step-by-step wizard, one-click action
High Ability, High Motivation

Signal

Simple reminder when both motivation and ability are high. Just needs timing.

Example: Alarm, notification, calendar reminder

Real-World Applications

Habit Formation

Start with tiny habits that require minimal motivation and ability. Use implementation intentions as prompts.

Product Design

Simplify onboarding, reduce friction, and use smart prompts at the right moment to drive user engagement.

Health Interventions

Focus on making healthy behaviors easy rather than relying on willpower alone.

Marketing

Create desire (motivation), reduce barriers (ability), and trigger action at the right moment (prompt).

Key Insights

1

Motivation is hardest to sustain. Focus on making behaviors easier and using better prompts instead.

2

Simplicity wins. Reducing friction is often more effective than trying to increase motivation.

3

Context matters. The same prompt works differently depending on motivation and ability levels.

4

It's multiplicative. If any element is zero, behavior won't happen regardless of other values.

5

Start tiny. Small wins build momentum and make difficult behaviors feel easier over time.

"Plant a tiny seed in the right spot, and it will grow without coaxing."

— BJ Fogg, Founder of Stanford Behavior Design Lab