A small head start that changes everything
Pre-fill one stamp — and twice as many customers complete their card.
This isn't a marketing trick. It's documented psychology. When people feel they've already started something, they're far more likely to finish it. Researchers call it the Endowed Progress Effect.
The experiment: two cards, one difference
In 2006, researchers Joseph Nunes and Xavier Drèze split customers at a car wash into two groups. Both groups had to return the same number of times to earn a free wash.
Group B
8 slots · blank
Group A
10 slots · 2 pre-filled
Both groups needed exactly eight return visits. The only difference: Group A felt like they were already underway.
Source: Nunes, J. C. & Drèze, X. (2006). The Endowed Progress Effect: How Artificial Advancement Increases Effort. Journal of Consumer Research, 32(4), 504–512.
Why it works
People experience progress differently from potential. Abandoning a task already started feels like a loss — not a neutral choice.
Add to that the goal gradient effect: the closer we are to a goal, the faster we move. Someone with two stamps already starts accelerating sooner than someone starting from scratch.
The pre-filled stamp isn't a trick. It activates two psychological mechanisms at once: it lowers the barrier to starting and raises motivation to keep going.
What this means for your shop
You don't need to be a behavioral psychologist to benefit from this. The principle works with any stamp card.
In practice: a bakery that adds a welcome stamp when handing out a new card. A café that spontaneously gives two stamps on the first visit. The card no longer looks empty, and the customer feels like they already belong.
That's not manipulation — it's hospitality. And hospitality that shows up in numbers is easy to justify.
What this looks like in numbers
Say you hand out 100 stamp cards in a month. Without a head start, about 19 of those customers complete their card. With one pre-filled stamp, you'd expect around 34.
Every completed card means multiple real visits. Someone who redeems their card is already a regular.
Give it a try
A head start works with any stamp card. A good system makes it easy to give one.