It’s obvious: Someone finding a lost wallet is less likely to return it if money is inside, right?

That’s what top economists, as well as regular people, usually predict, given what most of us assume about human nature. But according to a clever new study involving thousands of people in 40 countries, what most of us assume about human nature is wrong.

The three-year study, possibly the largest real-world test of whether people behave honestly when given incentives not to, found they are actually more likely to return lost wallets containing money. And the more money, the better the chances people will return it.

Experts say the study, published Thursday in the journal Science, suggests that policymakers and businesses might better prevent dishonest behaviors like lying on tax returns by using moral carrots instead of punitive sticks.

“It shows that when we make a decision whether to be dishonest or not, it’s not only ‘What can I get out of it versus what’s the punishment, what’s the effort?’” said Nina Mazar, a behavioral scientist at Boston University who was not involved in the study. “It actually matters that people have morals and they like to think of themselves as good human beings.”