After using the restroom, people washed their hands properly most often if they felt watched or were shamed into it, according to a study by the London School of Hygiene and Tropical Medicine and reported by Reuters.

For the study, researchers monitored the soap usage of 250,000 toilet-users at motorway service stations in Britain for 32 days. In addition, they flashed messages in the restroom to encourage hand washing.

One message—“Is the person next to you washing with soap?”—received the strongest positive response, causing 12 percent more men and 11 percent more women to use soap.

Without reminders, however, only 32 percent of men and 64 percent of women lathered up.

Also of interest to researchers was the “intriguing” gender differences in response to the reminders. Men responded best to messages prompting disgust, while simple reminders resulted in the desired response from women.

Health officials worldwide are increasing efforts to convince people to improve their hygienic habits and properly wash their hands to help slow the spread of H1N1.

“It could save more than a million lives a year from diarrheal diseases and prevent respiratory infections—the biggest causes of child mortality in developing countries,” study authors said.

Learn how you can wash your hands of the flu here.