Good habits are difficult to establish. A little bribery, on the other hand, can go a long way. This is the conclusion of an experiment in India that used rewards to get villagers to wash their hands regularly. While tying rewards to desired behaviours has long been a habit formation staple, handwashing has proven difficult to maintain.

Just making handwashing a pleasant, easy activity improved health: Children in households with thoughtfully designed soap dispensers experienced fewer illnesses than children in families without those tools. Dr. Reshmaan Hussam, Dr. Natalia Rigol from Harvard Business School; Dr. Rigol Giovanni Reggiani from MIT and Atonu Rabbani from the University of Dhaka reported in the American Economic Journal: Applied Economics.  

The rewards worked. “If you bribe kids, handwashing rates shoot up,” says developmental economist Dr. Hussam. Notably, good habits persisted even after researchers stopped rewarding them.  

Between August 2015 and March 2017, 2,943 households in 105 villages in West Bengal were studied. Everyone had access to soap and water. Even though nearly 80% knew soap killed germs, only 14% reported using soap before eating.

Hussam’s team devised a method to monitor handwashing in the absence of observers — whose presence typically causes people to behave better. The team created a soap dispenser with a hidden sensor that recorded it whenever used in collaboration with the MIT Media Lab.

They then taught families how to develop good handwashing habits, such as setting a trigger (dinner time) and a routine (handwashing right before meals). They also tried to make the handwashing experience as enjoyable and straightforward as possible, such as using scented soap and placing the sensors in places where children could easily reach them. Every two weeks, researchers visited households to collect data on children’s health and refill the dispensers.

Hussam’s team classified households into several categories. Some families only received a dispenser. Others received automated reports on their daily handwashing performance, which served as a social incentive to gently prod routine behaviour. Others received tickets whenever they pressed the dispenser around dinner time; these tickets could be exchanged for toothbrushes, backpacks, and other valuable items. A control group did not receive any dispensers.

One to four months after receiving a dispenser, the team discovered that people used soap at dinnertime 36% of the time in households that received no incentives. Those who received automated reports used soap 45% of the time. Those who earned tickets used soap 62% of the time.

When the rewards and feedback stopped, the use of soap dropped precipitously. With little to lose, the researchers decided to keep the sensors turned on. Handwashing rates among households that received incentives increased slightly over time. After nine months, homes that had received tickets washed their hands 16 percentage points more than households with only received dispensers.

The team believes that the return of cold and flu season reminded parents to wash their hands with soap. Hussam speculates that “when parents notice that their children are sniffly or sneezing, that’s when they’re triggered to use the device.” “Habits are frequently linked to specific cues.”

Even children who lived in households with only a dispenser and no rewards had better health than children who did not live in families with a dispenser. Children with soap dispensers in their homes had 38 percent fewer days with diarrhea and 16 percent fewer days with respiratory infections eight months after the incentives ended. Access to a well-designed dispenser was also linked to children’s healthier height and weight.

A valuable lesson emerges for product designers hoping to guide people toward good habits: “Think carefully about human-centred design,” Hussam advises.