The toilets in motorway service stations have recently been used for a very interesting experiment. Electronic boards were used to flash up messages about handwashing, and soap dispensers were fitted with sensors.

During the experiment, 250,000 people used the toilets. Only 32% of males washed their hands with soap afterwards, compared to 64% of the females.

Messages ranged from polite reminders to those aimed at shaming people into washing their hands. Males generally reacted better to messages that made them feel disgusted, such as: “Soap it off or eat it later”. Females were more likely to wash their hands if they saw messages that reminded them of things they already knew, such as: “Water doesn’t kill germs, soap does.”

Scientists say that washing hands with soap is an easy way to save millions of lives a year, by stopping the spread of various diseases.