BJ Fogg, who runs the Behavior Design Lab at Stanford, has a finding that sounds almost too small to matter: adding roughly 20 seconds of friction to an action can cut how often people do it by a wide margin, and removing 20 seconds of friction from a desired action can increase follow-through by a similar amount. Twenty seconds. Not a lecture, not a willpower intervention — just a small delay inserted at the right point.
Motivation is the least reliable lever you have
Fogg's broader model treats behavior as a function of motivation, ability, and a prompt — and of the three, motivation is the one that fluctuates the most and is hardest to engineer for. Ability, on the other hand, is mostly about friction: how easy or hard the action physically is to do. Friction is something you can actually design, on a day when your motivation is exactly average, which is most days.
Why this matters more for phones than almost anything else
A phone is the lowest-friction distraction ever built — it's already in your hand, already unlocked half the time, and the app you're about to open takes one tap. There's essentially zero friction standing between impulse and action, which is precisely the condition Fogg's model predicts will produce the most automatic, least-considered behavior.
What this means for how blocking should actually work
The lesson isn't "try harder not to open the app." It's "put meaningful friction back between the impulse and the app" — and a scheduled, OS-level block is about as much friction as you can add, short of not having the phone at all. That's the actual design principle behind Appblox: it's not a tracker asking you to feel guilty about your numbers, it's friction, inserted deliberately, at exactly the moments you decided in advance that you wanted it there.