
Look at that image: same basic punch card idea, wildly different results. The blank 8-slot card gets a meh 19% completion rate. The 10-slot card that starts with two spots already stamped jumps to 34% completions. Same reward, same effort, but a tiny psychological tweak doubles how many people finish.
People don’t crave “rewards” as much as they crave “finishing something they already started.” When you hand someone a loyalty card that’s completely blank, it screams, “You’re at zero.” When you hand them a card with a couple of spots already stamped, it screams, “You’re already on your way—might as well finish.” That little illusion of early progress flips customers from casually interested to quietly committed.
Starbucks shows customers a nearly-filled star meter in its app, making that final coffee purchase feel like completing an almost-finished card.
Duolingo starts new users with a half-completed progress bar and an instant streak badge, nudging them to keep coming back to “not break it.”