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Human sense of vision and smell can detect a disease before it breaks out, and make us avoid sick people.
Researchers injected harmless bacteria on participants and activated the immune response in another participants, who developed the classic symptoms of disease.
Symptoms like tiredness, pain and fever for a few hours, they were photographed and filmed. The injected substance and symptoms then disappeared from their bodies.
Another group of participants were exposed to the images and asked to rate how much they liked the people, while their brain activities were measured in an MR scanner.
They were asked to look at the photographs and identify sick and healthy participants.
The result shows that brain is good at picking weak signals from multiple senses relating to a person’s state of health. Avoidance does not apply if
you have close relationship with the sick person.