Reading Others
Start with the eyes to determine whether someone is relaxed or troubled, says Navarro, who famously caught the US ice-pick killer by studying his eyes.

When the eyes are narrowed – what Navarro calls the Clint Eastwood effect – it indicates discomfort, stress or anger. Rapid blinking, meanwhile, suggests someone is nervous or under stress. When people are truly comfortable they will look away to retrieve facts from their memory or ponder their point.

Assessing the eyes and eyebrows together can also be revealing: widened eye lids and raised brows indicate fear; high u-shaped eyebrows suggest surprise; drooping eyelids with eyebrows tensely drawn up and together means sadness; and eyebrows pulled down and together indicate anger.

Other parts of the face visible outside the mask can be helpful too: activated upper cheeks with crinkled crow’s feet mean genuine happiness whilst wrinkling on the bridge of the nose – what Navarro calls “the bunny nose” – signifies disgust.

The feet can also offer powerful clues about how someone is feeling. The writer and zoologist Desmond Morris has observed that the feet and legs are the most ‘honest’ part of the body. “By social convention we have to be nice to each other,” says Navarro. “But feet have no such convention. If I see someone I don’t like at a party I might nod but my feet will turn away.”

Reassuring Others
Navarro, who now wears a mask every day in his home town of Tampa, Florida, suggests adopting certain behaviors to reassure others in these extraordinary times.

Even under normal circumstances we can be bad at assessing how much physical space people need in order to feel comfortable, he says. “I once asked an audience of 1,200 people whether anyone had ever invaded their space. Every hand went up.”

He adds: “My eyes would engage them using gravity-defying behaviors like eyebrow flashes. This is one of the most ancient behaviors we have (if you want to make a baby happy, flash your eyebrows and they will smile). I would also give a genuine smile that engages the muscles around the eyes.”

Once conversing, Navarro suggests nodding and using head tilts to encourage and convey interest. We are wired to respond to head tilts as this is a gesture we see as babies when our mothers hold us in their arms and tilt their heads to look at us.

“I think people around the world will become more comfortable wearing masks,” he adds. “We will get used to them.”

Public health experts agree and are encouraging people to think of mask-wearing as a socially responsible act. “I wear a mask to protect you and you wear a mask to protect me,” KK Cheng, professor of public health at the University of Birmingham, told StoryCode. “If everyone wears a simple DIY mask, everyone is protected. We must do it.”

Perhaps soon masks will be associated with courtesy rather than villainy.

This anti-smog mask from London’s Great Smog in the early 1950s solved the problem of shielding the face without obscuring it. However, perhaps unsurprisingly, it did not catch on.