Behavior Design:

A Practical Guide

Behavior design is a practical method for making a specific action happen. It works when motivation and ability meet a well-timed prompt. Keep the action small, remove friction, and place the prompt in the moment where the choice is made.

Origins and core idea

Behavior design grew out of applied work in psychology and human-computer interaction. The practical rule is simple. Choose one clear behavior, make it easier than it feels, and trigger it at the right moment. BJ Fogg’s work at Stanford popularized a clear model and a set of small-step practices that teams can apply without heavy research overhead. The focus is on a single action in a specific context. You change the context, the ability required, or the timing of the cue.
Typical sequence: define the behavior in plain language, identify the actor and context, strip away steps, and place a prompt where the choice naturally happens. The output is a smaller action that succeeds more often. Repeated success raises confidence and creates a path to larger changes.

The Fogg Behavior Model, explained simply

B = MAP. A behavior happens when Motivation, Ability, and a Prompt Come together at the same moment.

  • Motivation: the person wants the outcome enough to act right now.

  • Ability: the action feels easy enough right now.

  • Prompt: a visible cue appears right now.

Prompt types and when to use them:

  • Spark: use when motivation is low. Add a small emotional lift or a clear reason at the moment of choice.

  • Facilitator: use when ability is low. Remove steps, prefill fields, or make the action tiny.

  • Signal: use when the person is willing and able. A clear nudge is enough.

How to apply in minutes:

  1. Pick one behavior. Example: “Book a 30 minute consult.”

  2. Make it tiny. Example: “Pick a time with one tap.”

  3. Place the prompt. Example: “Button appears at the end of the page after a relevant section.”

  4. Remove friction. Example: “No account creation. Two fields only. Calendar opens prefiltered.”

Gray T-shirt with blue text that reads 'SEND LAWYERS GUNS & BEHAVIORAL SCIENCE'.

Practical examples

Product, freemium signup

  • Goal behavior: start a free trial.

  • Make it tiny: email only, one click sign in.

  • Prompt: button appears after feature list and again on exit intent.

  • Why it works: ability rises when fields drop, prompt hits at decision peaks.

Email capture on a blog article

  • Goal behavior: subscribe.

  • Make it tiny: single field, no CAPTCHA unless abuse is detected.

  • Prompt: inline form after the first helpful section and again at the end.

  • Why it works: prompt matches reading context, action is fast.

Clinic appointment reminder

  • Goal behavior: confirm appointment.

  • Make it tiny: tap a link that opens a prefilled confirmation.

  • Prompt: SMS at 24 hours and a Signal in email at 2 hours.

  • Why it works: timing matches when people plan. Confirmation is one tap.

Support handoff inside a product

  • Goal behavior: move from chat to scheduled call.

  • Make it tiny: pick a slot from three options. No login.

  • Prompt: link appears after the second failed self-serve attempt.

  • Why it works: Facilitator prompt arrives when ability feels low. Choice set is small.

FAQs

What is behavior design?
A method for producing a specific action by tuning motivation, making the step easier, and adding the right prompt at the right time.

How is behavior design different from behavioral economics?
Behavioral economics explains patterns in decisions. Behavior design builds a small action in a specific moment and environment.

What are Sparks, Facilitators, and Signals?
Three prompt styles. Spark raises motivation. Facilitator makes the step feel easier. Signal is a clear cue when the person is already willing and able.

Do I always make the behavior tiny?
Start tiny to raise success rates. Once success is reliable, grow the action.

Where should I place prompts?
Place prompts in the tool and moment where the choice happens. End of an article, inside a workflow, or right after a relevant event.

How do I raise ability fast?
Cut steps, prefill forms, reduce choices, and allow progress without an account when safe.

How do I measure success?
Track the single action as a completion rate. Example: confirm, subscribe, book, start trial.

Is this ethical?
State the value plainly, allow refusal, and avoid dark patterns. Use prompts to reduce friction, not to trap people.

References and further reading