Do customers return excessive change in a restaurant?

The article reports the results of a field experiment used to study dishonest behavior in a natural setting. Customers in a restaurant in tables of one or two diners who paid with cash received excessive change of either 10 or 40 Shekels (about $3 or $12). A majority of customers (128 out of 192) did not return the excessive change. Repeated customers returned the excessive change much more often than one-time customers. Women returned the extra change much more often than men, especially among repeated customers. Interestingly, a table with a woman and a man behaves similarly to one or two males and not to a female table. Surprisingly, tables with two diners were not significantly more likely to return the excessive change. Customers receiving 10 extra Shekels were much less likely to return them than those who received 40 extra Shekels, but it is hard to know to what extent this comes from intentional behavior versus lower likelihood to observe the extra change when it is lower. We also found evidence for variation in dishonesty as a function of the time during the day.