This Post Will Make You…

I’ve always suspected that the reason people find it harder to leave a Netflix series than a religious cult is not because of the content, but because they’ve started something and haven’t finished it. Enter the Zeigarnik Effect, a psychological quirk discovered by a Soviet psychologist in the 1920s, which, in true Soviet fashion, was first observed in overworked waiters rather than underpaid lab rats.

Bluma Zeigarnik noticed that waiters could flawlessly remember unpaid orders, but forgot them almost immediately once paid. In other words: we remember what is incomplete. Our brains, it turns out, are not strictly storage devices but also very fussy project managers. The moment something’s wrapped up, it gets filed away. But until then, it lingers in our mental inbox like an unanswered WhatsApp message from someone you’d rather ghost.

And this, ladies and gentlemen, can be a marketing goldmine.

This is why gamification works, why progress bars are more powerful than discounts, and why even grown adults will log into Duolingo just to maintain a streak that has long since stopped making any rational sense. That half-finished act has psychological gravity. We are compelled to close the loop.

It works in education, fitness apps, loyalty programs, political campaigns, email onboarding flows, even in how you design a landing page headline. Don’t give it all away. Leave something undone. Make the user lean forward.

Everyone bangs on about how content is king—but they forget what really keeps the kingdom alive: curiosity. In a world obsessed with conversion, a little strategic incompleteness might be your most powerful tool.

If you’re building anything that asks for attention, learn to love the cliffhanger.