Walk into a diner in the United States and leave less than 15% on the table, and you’ll likely feel a twinge of guilt. Walk into a restaurant in Istanbul and the calculus is different. Tipping happens, but the amounts, the customs, and the social pressures don’t map cleanly onto the American experience. That raises a practical question for anyone who has read the popular research on server tricks that boost gratuities: do those tricks travel?
A new set of three field experiments published in the European Journal of Marketing set out to answer exactly that. The researchers tested whether well-known tipping tactics documented in American restaurants, such as writing “thank you” on a check or drawing a smiley face, produce the same lift when tried in Turkey.
Why test tipping tricks outside the U.S.?
Much of the behavioral research that marketers, managers, and hospitality trainers rely on comes from a narrow slice of humanity. One often-cited review found that roughly 80% of samples in top psychology journals come exclusively from English-speaking countries that are Western, educated, industrialized, rich, and democratic, a cluster researchers call WEIRD. Those countries house only about 6% of the world’s population.
Tipping is a case where that bias matters. Customs vary dramatically across cultures. A tactic that boosts gratuities in Pennsylvania may be socially awkward, meaningless, or even off-putting elsewhere. The research team, led by Anıl Savaş Kılıç, an independent researcher based in Istanbul, along with colleagues at Piri Reis University, Istinye University, SWPS University in Wroclaw, and the University of Agder in Norway, wanted to see which effects hold up and which don’t when the setting shifts.
They picked three classic studies to revisit, each published in the 1990s by researcher Bruce Rind and colleagues. Rather than reproducing them exactly, the team ran what are called conceptual replications: similar experiments adapted to a Turkish context, designed to test the same underlying ideas rather than copy every detail.
Experiment one: the power of “thank you”
The first field experiment took place over a week in a mid-scale restaurant in central Istanbul. Four waiters and two waitresses served customers as usual, but for each dining party they drew a card that assigned one of three conditions. Some parties received a completely blank check. Some got a check with “thank you” written on the back. A third group received “thank you” with the server’s first name added beneath it.
The study covered 388 dining parties, or 1,013 individual diners. The researchers measured tip amount, tip percentage, and whether any tip was left at all.
Both written messages produced larger tips than the blank check. The generic “thank you” lifted tip percentages, and adding the server’s name lifted them a bit further. The original 1995 Rind and Bordia study had found no difference between the generic and personalized notes, but with a sample roughly seven times larger, the Turkish replication was able to detect a small additional boost from personalization. The researchers attribute the difference to statistical power rather than culture.
One thing that did not change across conditions was whether people tipped at all. More than 90% of parties in every group left something. The written notes nudged the size of the tip among people already inclined to tip, not the decision to tip in the first place.
Experiment two: a smiley face on the check
The second experiment, run over a week in a higher-priced Istanbul restaurant, tested whether drawing a small smiley on the back of the check would raise tips. Servers pulled a bead from their pocket, black for a blank check and white for a smiley, to randomize the assignment. The study included 214 parties totaling 516 diners.
Diners who received a smiley left an average tip of 12.47% of the bill. Those who received a blank check left 9.52%. The difference was statistically reliable and held up after accounting for party size and payment method.
This result extends the original 1996 Rind and Bordia finding in an interesting way. In the U.S. version, the smiley only worked for female servers; for male servers, it produced no effect. The Turkish data showed a general boost, though the researchers note a limitation: they did not record the gender of the server for each check, so they can’t rule out that the aggregate effect hides gender differences underneath. What they can say is that, on average, the smiley lifted tips.
Experiment three: wishing customers a sunny day
The third experiment tested whether a cheerful weather-related message would influence tipping. On a cloudy Monday with air temperatures around 7°C (about 45°F), five servers at a high-street Istanbul restaurant delivered checks to 92 dining parties. A research assistant near the cash register drew from a deck of red and black cards to assign each party to either a blank check or a check bearing the handwritten message “Wish you a sunny day.”
Tips rose from an average of 4.81% in the blank-check group to 7.13% in the well-wish group. The authors connect the effect to what psychologists call feelings-as-information theory, the idea that pleasant cues such as the suggestion of sunshine lift mood, and lifted mood in turn prompts more generous behavior.
The bigger surprise: Turkish tips run much smaller
Across all three experiments, the treatments worked in the expected direction. But the absolute numbers tell a second, arguably more interesting story. The best-performing condition in each Turkish experiment produced a tip percentage far below the worst-performing condition in the corresponding American study. In other words, even the most effective nudge in Istanbul generated smaller tips than an ordinary blank check in the United States.
That gap is the clearest sign that tipping norms are culturally contingent. Servers and managers can still move the needle with small gestures, but the baseline they’re moving from looks very different depending on where the restaurant sits.
What the results suggest for service managers
For restaurant operators outside the U.S., the experiments offer a few concrete takeaways. Handwritten gestures on the check, whether a thank-you note, a smiley, or a friendly weather wish, consistently raised the average tip size. Personalization, in the form of a server’s name, added a small additional lift. The tactics are cheap, easy to train, and did not appear to change whether customers tipped, only how much.
There are limits to what the study can claim. The experiments were confined to Istanbul restaurants on specific days, and the third study ran for only 7.5 hours. The authors also flag that they did not test whether a typed or pre-printed message would work as well as a handwritten one. Prior research suggests handwritten communication tends to feel more authentic and warmer, but that’s a question for future work.
The researchers suggest that subsequent studies could explore whether these small gestures ripple outward, shaping customer satisfaction, loyalty, or even perceptions of the food itself. For now, the clearest conclusion is that some familiar tipping tactics do generalize beyond American restaurants, even as the size of the tipping pie looks very different from place to place.
