People in the UK are being asked to improve their personal hygiene in an effort to limit and slow the spread of coronavirus. But how's the government going about it?
Don't touch your face.
It's something people are thought to do more than 20 times an hour on average, but the official advice is to desist so that coronavirus doesn't spread any faster.
It's not easy to give up unhygienic habits picked up over a lifetime, though.
So the government is using "Nudge theory", a branch of economics designed to get us to do the "right thing" by making it easier, more normal and more obvious.
The Behavioural Insights Team (BIT), a company part-owned by the Cabinet Office, is advising ministers on how best to do it. It's come up with some ideas to prevent face-touching, as featured on its blog.
How about asking friends, family or colleagues to shout "face" every time they see you're about to reach up for a scratch or rub?
Or folding your arms in a locked position, grabbing the biceps to avoid the hands slipping free and heading upwards?
Another suggestion is creating an alternative "habitual" action, such as drumming fingers on legs or playing with a substitute object, such a ball.
"Even if you're very concerned about coronavirus, it's very difficult to stop doing something like face-touching because it's such a habit," says Cynthia McVey, former head of psychology at Glasgow Caledonian University. "There have been reports of people who are worried enough to wear masks who have still removed them so they can rub their nose."
Nudge theory, already widely used by governments, aims to instil better habits - or change social "norms" - rather than focusing on explicit "top-down" advice.
If enough people do something, you feel a sense of oddness, of missing out, of guilt perhaps, if you don't do the same.
"It's more powerful than traditional methods of getting across certain advice," says Kelly Hunstone, chief executive of the Social Change UK agency and a former adviser on behavioural science to the government. "We've left the age of deference and need to communicate differently.
"In some instances we don't trust the experts but the person on the street to show us how to act. It's a bit like using Tripadvisor - you'd rather take the advice of Bob in Essex than a travel operator."
Since the coronavirus crisis began, the government has recommended singing Happy Birthday to yourself twice while washing your hands. It's easier to remember than counting the full 20 seconds this equates to.
We've also been advised to sneeze into our sleeves if there are no tissues around.
Both tips bear the signs of Nudge theory, which emphasises putting across a "clear message".
Nudge theory also assumes people don't always act in their own best interests, or those of society - for reasons such as laziness, selfishness and ignorance. Hence the need to ease the way towards doing what a government wants us to do.
It's an idea that has caught on at local and national level since the book Nudge, by US academics Richard Thaler and Cass Sunstein, was published in 2008.
Some UK councils provide recycling bins that are larger than their normal waste bins, in an effort to get people recycle more.
Tax reminders are sent out saying the "majority" of people in an area have already paid, putting social pressure on recipients to do the same.
What can be done, though, to deal with the effects of coronavirus on society? The government is urging people not to stockpile toilet paper, pasta and other goods, while supermarkets are putting up notices asking people not to over-purchase and leave others without.
The logic is clear, but Ms Hunstone advocates a more Nudge-y, emotion-led approach.
"It would be more effective to show a picture of Doris Jones, 76, who can't get out easily to visit the supermarket, if you're trying to persuade people not to buy too many cans of baked beans or loo rolls," Ms Hunstone says.
She argues that pictures like this, seen recently on Facebook, could be placed in shops, inducing guilt in those tempted to stuff their trolleys.
"It's also important to use the ego when you're putting out this kind of message and people like to be seen doing what's right," Ms Hunstone adds.
People leaving enough provisions on shelves could photograph their trolleys or baskets and share them on social media, further marginalising those who do not, she says. So, in a way, "annoying" virtue-signallers could encourage the spread of virtuous behaviour in others.
The UK government has faced criticism for adopting a different approach to other countries towards coronavirus, focusing more so far on people following advice than creating a wider "lockdown".
Prime Minister Boris Johnson has signalled a change of approach this week, urging people to reduce social contact with others, but the measures are less severe than in many other European countries, necessitating simple advice.
Staff with the Behavioural Insights Team are honing and testing messages to create the greatest impact.
"Simplicity is key," says Ms Hunstone. It might get boring hearing the same thing again and again. But you have to hear messages like that nine times before people really understand them and they get through. Consistency is absolutely vital."
There have been criticisms that Nudge theory infantilises people, not crediting them with the ability to think for themselves and removing effective choice.
But it's very much in favour in Downing Street. Whether it can stop people touching their faces remains to be seen.