A few years ago, researchers Reshmaan Hussam and colleagues decided to find out why many people in the developing world fail to wash their hands with soap, despite lifesaving benefits.


In partnership with engineers at the MIT Media Lab, the researchers designed a simple wall-mounted soap dispenser with a time-stamped sensor hidden inside (to track usage). The researchers randomly divided the villages into “monitoring” and “incentive” villages, taking two approaches to inducing the handwashing habit.

 In another group, people learned that they initially would receive one ticket (which can be redeemed against a good) each day for washing their hands with soap, but that in two months they would begin receiving triple the number of tickets for every day they used the dispenser. The final group received the same incentive boost two months into the experiment, but it was a happy surprise: The group had no prior knowledge of the triple-ticket future.

The result?

The results showed that both monitoring and monetary incentives led to substantial increases in handwashing with soap.

Households were 23 percent more likely to use soap if they knew they were being monitored. And some 70 percent of ticket-receiving households used their soap dispensers regularly throughout the experiment, compared with 30 percent of households that received the dispensers without incentives.