UX Unpacked: Using the Fogg Behavior Model to Diagnose Product Adoption

The Fogg Behavior Model, developed by Dr. BJ Fogg at Stanford University, is a simple framework used by product teams worldwide to understand why users might not adopt features as intended. The model is based on the formula Behavior = Motivation × Ability × Prompt. If any one of these three elements is missing, users won't perform the action.

Motivation refers to a user's desire to perform an action, which can fluctuate over time. Three sources of motivation include internal desire, external rewards, and environmental influences. Ability refers to how easily a user can perform an action, influenced by factors like time, cost, physical effort, mental energy, and routine fit. A prompt is the trigger that reminds users to take action, coming in three types: facilitators, signals, and sparks.

The model is visualized as a graph with motivation on the vertical axis and ability on the horizontal axis, with a curved line separating where behavior happens from where it doesn't. If a behavior is easy, users need less motivation. If it's hard, they need more motivation. Any behavior not happening is due to a missing element.

To diagnose missing behavior, designers should first check for a prompt, then assess the ease of the action, and finally, determine if users genuinely want to perform the action. Fixing motivation is a last resort, as prompts and ability improvements usually have a greater impact.

The Fogg Behavior Model provides a diagnostic framework for stuck features, a prioritized checklist for improvement, and a common language for teams. It emphasizes helping users do what they already want to do and feel successful, avoiding manipulative design tactics. Future articles in this series will cover additional mental models for interaction design.