Sometimes, doctors are able to tell a person is sick just by looking at their face. Now, researchers have revealed this is not a skill acquired in medical school, but a general human ability. Most humans can identify a sick person judging from certain hints present on their face. Researchers say they have evolved this as a way to avoid getting ill by avoiding contact with ill people.
They took photos of people after causing an immune response in their organisms
Researchers knew that not only doctors could detect an illness on a person’s face, so they decided to see if this is a general human skill. For this, they developed a study where they used 16 healthy people aged between 19 and 34 whose photo was taken. Then, they were given a shot of a compound called lipopolysaccharide, which induces flu-like symptoms over a short period of time.
These people exhibited different immune responses to the compound. Some of them felt extremely sick, while others felt like nothing much had changed at the moment they had to pose for the photo. However, soon afterwards, everyone was ok. This compound is not dangerous, and is often used for the study of the immune response it causes.
The success rate was high, showing humans can judge sick people by their face
The researchers took a photo of the people before the shot, when they were healthy, and then two hours after they had been injected. Then, they were about to show the photos to other people and see if they could notice any difference. The next day, they received a placebo treatment, which wasn’t meant to exhibit a real immune response, and had their photo taken again.
They collected 32 different photos they showed to other participants, and gathered a total of 2,945 ratings. The task was to rate the people in the photo as sick or healthy. They got it right 775 times and wrong 440 times, reaching a high accuracy rate. This way, researchers established human can accurately spot a disease just by looking at a person’s face.