Lost wallets are more likely to be returned if they hold cash

If you’re prone to losing your wallet, keep it filled with cash.

That’s a tip from researchers who “lost” over 17,000 wallets in 40 countries. In all but two countries, the likelihood of a stranger returning a wallet increased if there was money inside. And the more money in the wallet, the higher the rate of return, the researchers report June 20 in Science. 

“We were expecting a lower return rate when [the wallet] had more money,” says behavioral economist Alain Cohn of the University of Michigan in Ann Arbor.

Cohn and his colleagues deployed 13 Swiss college students, wallets in hand, to 355 cities across the globe. Each wallet was clear, letting a finder see the contents without opening it. And each contained a grocery list in the local language, a key, three identical business cards with a local-sounding man’s name and an e-mail address. Some of the wallets had no money in them, while others held $13.45 or the equivalent buying power in local currency. The research assistants then turned the wallets over to employees of banks, museums, post offices, hotels and police stations along with a note, reading: “Hi, I found this on the street around the corner. Somebody must have lost it. I’m in a hurry and have to go. Can you please take care of it?”

Those wallet drop-offs were not without hiccups. Flooding in India rerouted the Swiss students, while authorities in Kenya detained one student for a few hours for appearing suspicious. All told, the students handed employees 17,303 wallets.  

Cohn and his team then calculated a “return rate” based on how many employees e-mailed the person on the business card within a 100 days to report the wallet as “found.” (Employees didn’t actually return the wallet, but were told after reporting it that they could keep the money or donate it to charity.)

On average, 40 percent of wallets with no money were reported found, compared with 51 percent of wallets with some money. The results varied by country: It was far better to lose a wallet in Denmark, where 82 percent of wallets holding $13.45 were turned in, than in Kenya, where the return rate was just under 20 percent. In the United States, 57 percent of wallets with money were given back. Mexico and Peru were the only two countries where return rates dropped when wallets held money, but those outliers were not statistically significant.

Country differences

Though return rates of lost wallets went up in most countries when those wallets contained money, baseline return rates varied widely from country to country. A wallet was considered “returned” if someone made the effort to contact its owner.

Return rates by country of wallets with and without money

That begs the follow up question: “What are the commonalities between countries that are closer in behavior to each other than other countries?” says Nina Mazar, a behavioral scientist at Boston University who was not part of this study.

The researchers conducted a second set of experiments in three countries — the United States, Britain and Poland — with almost 3,000 wallets. When the amount of money increased to $94.15, return rates jumped to 72 percent on average.

To measure whether altruism was at play, researchers put a key — worthless to the finder, but valuable to the owner — in some of the wallets. Those with both money and keys were more likely to be returned (61 percent) than those that had money but no key (52 percent). The researchers say that offers some evidence of altruism, but not enough to explain why so many more people returned wallets with money than without.

Surveys of 2,525 randomly selected people in those three countries better revealed people’s possible motivations. Respondents were told to imagine receiving a wallet with money and without, and then asked: “To what extent would it feel like stealing if you do not contact the owner?” Feelings of stealing went up as the value of the wallet’s money increased, but were unchanged by the presence or absence of the key. Overall, decisions to return wallets were motivated less by thoughts of the wallet’s owner than by not wanting to feel like a thief, Cohn says.

This field study builds on lab studies showing that people work hard to protect the image they have of themselves, Mazar says. Her work has shown that having people sign an honesty statement before filling out car insurance forms, rather than at the end, reduces cheating. Interventions that tap this psychological quirk are inexpensive and easy to implement, Mazar says.