Definition
Behavioral design is designing products and programs around what people actually do, not what they say they’ll do. It starts from a behavior, which The Behavioral Startup defines as “a specific, observable action that a person takes in response to a particular situation or stimulus”, finds the barrier that stops it, and designs for that barrier.
Rule 0: the rule everything serves
“People must obtain more value from your product than the effort the product demands from them.”
Rule 0, The Behavioral Startup
The book calls it the foundation of user retention. When the scale tips the wrong way, more effort than value, people stop using the thing, or never really start. Every model in the method is a way to check that sentence piece by piece: who puts in the effort, what they get back, and when they notice it.
The Behavioral Handbook restates it with two parentheses that change the whole game: people must (perceive they) obtain more value than the effort (they perceive) the product demands. A product can save someone real money and still feel worthless if they never notice.
When a behavior doesn’t happen: four questions
Zoom into the moment a behavior happens or doesn’t. The engine under both books is the Behavior Model that B.J. Fogg laid out at Stanford: a behavior happens when a trigger is noticed and, at that same moment, the person is able enough and motivated enough to act. Add the lever almost nobody gets right, whether they noticed it worked, and you get four questions:
- Did they notice? Triggering. If nothing reminds them the option exists, they didn’t decide against you. They never started.
- Could they? Ability. When something is impossible, or just hard enough to feel impossible, motivation can’t rescue it.
- Did they want to? Motivation. Ease without a reason goes nowhere.
- Did they see it worked? Value evident. Effort that pays off invisibly feels, to the brain, exactly like effort that didn’t pay off at all.
When a behavior doesn’t happen, one of four things failed: they didn’t notice (triggering), couldn’t (ability), didn’t want to (motivation), or didn’t see it worked (value evident).
Ask them in that order. People mostly agree on what’s hard and disagree wildly about what’s worth it, so fix triggering and ability before you wrestle with motivation. The full diagnosis, barrier by barrier, is in why people don’t use your product.
The ANVERSO models
The Behavioral Startup turns Rule 0 into a step-by-step method. Pull the sentence apart and the models fall out, each one using what the previous one found:
- A, Actors. Who your product asks effort from, and which role each one plays: uses, pays, decides usage. The user is rarely the only one.
- N, Needs. What each actor needs, sorted with Clayton Alderfer’s ERG theory: existence, relationships and growth.
- VE, Value Evident. When and how each actor notices the value arrived. If they can’t see, hear or feel it, for them it doesn’t exist.
- RSO, behavioral funnels. The Required behaviors, through their Steps, to the Objective behavior, and the barriers sitting along the way.
The name is also the point: anverso is Spanish for the front side of something, the right way around. Start from behaviors, not features. The book site has the ANVERSO models, one by one, and the book walks you through each with templates and examples.
Behavioral design vs UX
UX asks “is this easy to use?” Behavioral design asks “does this actually change what people do?” UX focuses on the interface. Behavioral design focuses on the decisions behind it: why people act, what stops them, and how to design for real behavior change.
They’re not rivals. The Handbook does warn about one habit, though: say “ability” and product people hear “UX” (fewer taps, cleaner screens, less friction in the flow). That work is real, and it’s usually where teams stop. But it’s one slice of one of the four questions. A perfectly usable screen still fails if nobody notices it, nobody wants what it offers, or nobody can tell it worked. And when a signal has to pop without turning ugly or annoying, that’s craft: a fine place to lean on a good UI designer.
Who wrote this
I’m Nacho Parietti, a behavioral designer and programmer based in Montevideo, Uruguay. I’ve worked with dozens of companies and organizations designing products and programs. I built the ANVERSO models after meeting, again and again, brilliant experts with deep knowledge and no method to turn it into products people use.
Where to go next: The Behavioral Startup (the method, available now), chapter 1 of The Behavioral Handbook (free), the glossary, and behavioral design consulting and talks.
