BAKERSFIELD, Calif. -- Regular hand washing is a critical part of preventing the spread of swine flu, but what is the best way to remind people to do it?

Studies from the United Kingdom have found that reminders in bathrooms that invoke shame or disgust are most effective at getting people to wash up.

Researchers used electric sensors to track water and soap usage for nearly a quarter of a million people, and they placed LED screens at the entrances of public restrooms with messages such as "Water doesn't kill germs, soap does."

But the ones that worked best were those that appealed to peer pressure, like "Is the person next to you washing with soap?"

Overall, women were better washers, with men washing only half as often as women did, and while women responded to general reminders, men were more likely to suds up if the reminders were meant to invoke shame or disgust, such as "Soap it off, or eat it later."