Question

How to know whether someone is sick or not?

Answer 1

To test whether facial cues alone can convey signs of illness, researchers gave 22 adults an injection of either a common bacteria or a salt-water placebo. Although the bacterial injections didn’t make the volunteers truly ill, it did trick their immune systems and trigger an inflammatory response. Soon after the shot, those who received the bacteria began to feel sick.

About two hours after their injections, the people were asked to sit for a photograph with a neutral expression and wearing no makeup. On a separate occasion, everyone returned and received whichever injection they hadn’t had the first time, and were photographed again.