Let's say you're a young person, around 30 years old. And you're the kind of person who likes to take risks. So maybe you're taking risks in your sexual relationships. You're not practicing safe sex.
What would make you change your behavior?
That's a question that's long been pondered by public health officials. And now new research from a World Bank-funded team in Lesotho, a tiny country in southern Africa, has produced a surprising answer.
Here's what happened.
Researchers wanted to see if they could reach individuals who are prone to taking risks in Lesotho, a country with very high rates of HIV infection. Forty percent of people between the ages of 30 and 34 are HIV-positive.
The researchers recruited 3,427 volunteers in 29 villages. One group would come back every four months to be tested for two sexually transmitted infections that are curable. Volunteers were given small gifts to come back every four months.
Another group also came back for a test every four months, but these people didn't get a promise of a small stipend. They each got a lottery ticket. And there would be a drawing every four months. Two men and two women in each participating village would get a $50 prize. That's a lot of money in Lesotho.
What the researchers found was extraordinary. After two years, there was a 21.4 percent reduction in HIV infections in the lottery ticket group compared with the volunteers who got the small gifts.
"A 21.4 percent reduction in HIV incidence is a very large reduction," says researcher Martina Bjorkman Nyqvist, who ran the study. In previous trials to change behavior regarding HIV risks, there's never been "significant reduction in HIV incidence," she says.
The researchers also identified the people in the study who liked taking risks. They had volunteers play a game to establish which of them liked gambling. And in that subset of risk-loving individuals who got lottery tickets instead of gifts, the reduction in HIV infection was about 60 percent, Nyqvist reports.
(In case you were wondering why the volunteers were not tested for HIV, it's because the study didn't want to eliminate participants who were already HIV-positive. Getting them to practice safe sex is critical to keeping rates of infection down.)
It's too soon to roll this out in a big way. The study needs to be replicated.
And you'd need money — not for the lottery tickets but more for the cost of the STD tests that need to be administered to all participants.
But Nyqvist has a clever idea for cutting the need for testing: Just get everyone who's participating a lottery ticket and tell the participants that if they win, they get the cash only if they test negative for HIV.
So that would create an incentive to practice safe sex. The same psychological forces that cause people to believe they're going to win the lottery are now working to tell them, "I've got to practice safe sex."
RENEE MONTAGNE, HOST:
Public health officials have long sought ways to stem the spread of AIDS. They've even resorted to creative, even quirky approaches, like paying people to practice safe sex, mostly with little success until now. NPR's social science correspondent Shankar Vedantam spoke with our colleague David Greene about new research from Lesotho, a tiny country in the southern Africa.
DAVID GREENE, BYLINE: Shankar, hi.
SHANKAR VEDANTAM, BYLINE: Hi David.
GREENE: So what is this new approach in the small country?
VEDANTAM: Well, Lesotho has very high rates of HIV infection, David. Among young people between the ages of 30 and 34, 40 percent are HIV-positive.
GREENE: That's a lot.
VEDANTAM: I was speaking with Martina Bjorkman Nyqvist. She's part of a research team funded by the World Bank. She told me she was particularly interested in finding a way to reach individuals who were prone to taking risks. Here she is.
MARTINA BJORKMAN NYQVIST: How can you try to target a program to risk-loving people, people who like to take risks? And if you like to take risks, maybe you're also taking more risks when it comes to your sexual behavior.
GREENE: What's the answer?
VEDANTAM: The answer, David, is gambling because who's more interested in taking risk than gamblers?
GREENE: That makes sense. But I mean, tie that to public health...
GREENE: ...If you can.
VEDANTAM: ...The goal of the researchers is to get more people in Lesotho to practice safe sex because if you practice safe sex, you're going to stem the transmission of HIV and other sexually transmitted infections. So what they did is they recruited 3,000 volunteers in 29 villages, and they divided them into different groups. For one group they said come back every four months to get tested for two sexually-transmitted infections. Now, both of these are curable sexually-transmitted diseases, but if you test negative, you just get a cash award. Let's say you get $2. For people in the second group, they did exactly the same thing, except they said if you test negative, you don't get a cash reward, you get a lottery ticket. And every four months they had a drawing were two men and two women in each village could win either $50 or $100. And in Lesotho, $50 or $100 is a lot of money.
GREENE: OK, so two different types of rewards, both of them trying to encourage safe sex. I mean, rewards for coming in and testing negative.
VEDANTAM: That's exactly right. And what they found, David, is something extraordinary. When researchers analyzed who's practicing safe sex by analyzing the rates of new HIV infections after two years, they find that the volunteers in the group who were offered the lottery tickets have 21 percent fewer people diagnosed with HIV compared to the volunteers who got the simple cash payout. Here's Nyqvist.
NYQVIST: 21.4 percent reduction in HIV incidence is a very large reduction. And what I should also say is that when we look at randomized controlled trials that are looking at behavioral intervention in HIV, no one has before found a significant reduction in HIV incidence.
GREENE: OK, so 21.4 percent reduction in HIV incidence among people who were offered these lottery tickets. Was she able to isolate and look at people who were more likely to take risk?
VEDANTAM: In fact, David, she did. Nyqvist and her colleagues had volunteers play a game before they started the study to establish which of the volunteers liked gambling. They found volunteers who liked risks and were given lottery tickets were significantly less likely to be diagnosed with HIV than volunteers who liked risks and got the simple cash payout. Here's Nyqvist again.
NYQVIST: The program was particularly attractive to people that like risks. So the magnitude of the effect is substantial, and it corresponds to a reduction in HIV of about 60 percent in the group of risk-loving individuals.
GREENE: Sixty percent - big drop in the group that really you want to target risk-takers. I mean...
GREENE: ...They're the people you worry about.
GREENE: One question, Shankar. They were using two other diseases in this study. Why not test for HIV itself when they did this research?
VEDANTAM: You know, David, I think this is actually one of the more ingenious aspects of the study and here's why - if you want to stem the transmission of HIV in a country, you don't just want people who are HIV-negative to be practicing safe sex, you want people who are HIV-positive to be practicing safe sex because that will really have a big effect on the transmission of the infection. If you tell volunteers that you're testing for HIV and they're going to get rewards only if they test negative for HIV, what that means in a country like Lesotho is you eliminate a significant portion of the population that is HIV-positive. By testing for these two other unrelated sexually transmitted infections, what you do is you're bringing in a larger amount of the population, including the people who are HIV-positive, who are an essential part of your target population.
GREENE: An essential part of - in terms of changing the behavior in stopping the spread of the disease.
GREENE: So if this is so successful, is it worth rolling out in this country and others in a big way?
VEDANTAM: You know, I have to say it's extraordinarily promising, David. But like all science, this is a study that needs independent replication. Nyqvist told me that the biggest cost in the program was not the lottery tickets, but the cost of administering the medical tests. And she had a clever idea on how to roll this out to a larger group. You can't test millions of people every four months, but what you can do is you can give everyone a lottery ticket upfront and tell them if you win the lottery ticket, you have to get tested, and you get the money only if you test negative. And what this does is it creates an incentive to practice safe sex because the same psychological forces that cause people to believe I'm going to win the lottery are now working to tell them I've got to practice safe sex.
GREENE: Shankar, interesting stuff as always.
VEDANTAM: Thank you, David.
GREENE: That's Shankar Vedantam. He regularly joins us on the program to talk about social science research. You can find him on Twitter @hiddenbrain and find this program @MorningEdition.
MONTAGNE: Plus, you can follow us @nprmontagne, @nprgreene and @NPRinskeep. Transcript provided by NPR, Copyright NPR.