Mind & Body

You Really Can Tell Someone's Sick Just By Looking at Them

We've already told you about how your brain makes you antisocial when you're sick. And your friends and coworkers probably appreciate that instinct. But even if you do find yourself wandering the streets while afflicted with this year's plague, people who see you will likely know that they should keep their distance. As it turns out, your gut instinct is a pretty good barometer of the health of others.

The Eyes Have It

In a 2018 study, a panel of 16 Caucasian participants were injected with either a placebo or something called a lipopolysaccharide, a molecule found in the outer membrane of bacteria that can trigger an immune reaction without infecting them — that is, make the participants feel sick without actually making them sick. Photos of those ill or not-so-ill participants were shown to a much larger group of people. When asked to guess which photos were of sick people and which were of healthy people, they managed to get the answer right a lot more often than you'd expect from random guesses. In fact, they correctly guessed the disease state of 81 percent of the participants at a rate better than pure chance. Clearly, your health is written on your face.

So what is it about the faces of sick people that tips off their infirm condition? The researchers identified several traits that advertise illness: pale skin and lips, droopy eyelids and corners of the mouth, face puffiness, eye redness, and the appearance of fatigue. Of those, two stood out as leading red flags. Pale skin (that is, skin with a dull hue, regardless of its actual color) and drooping eyes were sure bets, so keep those features in mind if you're trying to avoid a bug.

For more about the tiny things you can pick up on without realizing it, check out Malcolm Gladwell's bestseller "Blink: The Power of Thinking Without Thinking." The audiobook is free with a trial of Audible. We handpick reading recommendations we think you may like. If you choose to make a purchase through that link, Curiosity will get a share of the sale.

More Accurate In Person

As accurate as their participants were in judging photographs, the researchers believe that the effect is probably stronger in person. That's because when you see somebody in the flesh, you can also assess things like their gait, their throatiness, and how much they complain about their sickness. In the future, say the scientists, they'd like to pinpoint some of the earliest warning signs of a gnarly cold or flu so that a sufferer can sequester themselves before they get too contagious.

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Written by Reuben Westmaas February 7, 2018