Face gives hints of illness
People can judge whether someone is sick by looking at a photo for just a few seconds.
That may not sound remarkable — until you consider that the sick people in the photos were in the very early stages of illnesses. They were participants in a scientific experiment and had agreed to be infected with a bacterium that would cause an inflammatory response. Their portraits were taken just two hours after infection.
Those pictures, along with portraits of the same people taken when they were healthy, were flashed in front of dozens of study volunteers in random order. The volunteers had no more than five seconds to guess whether the person in the picture was sick or healthy.
In the first series of ratings, 62 volunteers made 2,945 judgments about 32 pictures (of eight men and eight women, each photographed after being injected with an E. coli endotoxin and after being injected with a placebo).
The volunteers guessed that 1,215 of those pictures were of people who were sick. Those guesses were correct 64 per cent of the time and incorrect 36 per cent of the time, according to a study published this week in the Proceedings of the Royal Society B.
Apparently, three of the 16 participants were particularly inscrutable; when they were removed from the analysis, the volunteers guessed right 81 per cent of the time, the study authors found.
On a scale on which 0.5 means guessing at random and 1 means guessing right every time, the volunteers scored a 0.62. In other words, they did significantly better than if they had just flipped a coin to decide whether someone was healthy or sick.
In the second series of ratings, 60 people looked at the same 32 photos and were asked whether the person in each picture looked sick and if they looked tired. The volunteers also rated eight specific “sickness cues” on a scale from 1 (no symptoms) to 7 (very high symptoms).
The ratings revealed that the people in the photos looked more sick and more tired after they got the E. coli injection than after they got the placebo. The raters also thought people had paler skin, paler lips, more swollen faces, redder eyes, more hanging eyelids and droopier mouths after they got the real injection than after they got the fake one.
Further analysis showed that all six of those facial cues influenced raters’ perception of a person’s health. So did tiredness.
But two other cues that got different ratings in sick people and healthy people — glossy skin and patchy skin — did not affect judgments about health, the researchers reported.
With all this in mind, take a look at the photos that accompany this story.
If they look a little funny, that’s because each is a composite of the eight men and eight women who agreed to get sick for the sake of science.
One side is made up of 16 portraits of people who were healthy, and the other is made up of 16 portraits of people who were just starting to get sick. Which side is which? If you guessed that the sick faces are on the left, you are ... correct.