Paying compliments pays off, at least when it comes to fast food, according to a study by Austrian economists involving 100 ice cream cones and 800 kebab wraps.

Innsbruck University researchers sent several people to fast food restaurants over a few days to buy soft serve ice cream, the university said Wednesday.

To measure the effect of praise and recognition in consumer interactions, the experimenters ended their order with: "You have the best ice cream in town."

They then left the shop to weigh their serving with a small scale.

They found that the praise got them 10 percent more ice cream on average than when they ordered without paying a compliment.

In place of praise, the researchers also tried tipping the salesperson while ordering.

The tip lead to a 17 percent larger serving, but after figuring in the value of the tip, the actual bonus worked out to only 7 percent.

Praising and tipping kebab vendors brought similar results.

Over several days, customers who paid compliments continued to receive larger portions than those two only offered tips.

While speaking about the results of the study, lead author Michael Kirchler said, "There is a tendency to underestimate immaterial incentives, such as recognition and praise, and to overestimate monetary incentives."

In the end, the food all went to good causes, the participants gave most of the ice cream to fellow pedestrians and the kebabs to charity.