·Psychology & Behavior
Section 1
The Core Idea
Cialdini's principle: people want to be consistent with their past commitments. Foot-in-the-door — a small yes leads to a bigger yes. Public commitments are stickier than private ones. The mechanism is cognitive dissonance avoidance. We rationalise past choices to maintain self-image.
Amazon's "customers who bought X also bought Y" exploits this at scale. Each purchase is a commitment that shapes future behaviour. You bought a Kindle — now the recommendations assume you're a reader. You bought running shoes — now the algorithm nudges you toward fitness gear. The purchase history creates an identity the system reinforces. Every subsequent click validates the original commitment and makes deviation feel inconsistent.
Subscription models weaponise the same mechanism. Once you've committed to Netflix, cancelling feels like admitting a mistake. You're not "someone who quit a streaming service." You're "someone who gave up." The annual fee creates a psychological contract: having paid, you seek to justify the payment through usage. Gym memberships operate identically — people keep paying $50/month for gyms they don't visit because cancelling would mean admitting they're not "the kind of person who works out." The commitment created an identity. The identity persists even when the behaviour stops.
The dark side: when a CEO publicly commits to a strategy in a board meeting or press interview, the commitment creates consistency pressure that actively resists pivoting. Changing direction doesn't just feel strategically wrong. It feels personally inconsistent. The mechanism that makes commitment a powerful persuasion tool becomes a cognitive trap when the thing you committed to stops working.
Freedman and Fraser's 1966 experiment made the pattern visible. They asked homeowners to place a large "DRIVE CAREFULLY" sign on their lawn. Most refused — 83%. But one group said yes at 76%. The difference: two weeks earlier, a different researcher had asked this group to display a tiny three-inch sticker. Nearly all agreed. That trivial yes changed everything. The small commitment altered how they saw themselves. They became "the kind of person who supports safe-driving campaigns." When the large request arrived, refusing it felt inconsistent with that self-image. A three-inch sticker produced a six-foot sign.
