Look closely at this optical illusion. In your opinion, does the rotating mask appear solid or hollow?A serious illness clarified thanks to an optical illusionIn posing this simple question to several test subjects, doctors also managed to learn more about a serious mental illness. If you see in the illusion a mask that is both solid and hollow, you can breathe a sigh of relief because your brain is well.On the other hand, if you see only a hollow mask, things might be more complicated. Doctors remarked that the test subjects that saw a concave mask also showed symptoms of schizophrenia. Schizophrenics are in fact incapable of perceiving this kind of illusion, seeing the mask as purely hollow.‘When they see concave faces, only ‘healthy’ subjects show a strengthening in the connections between two parts of their brain. These connections allow the brain to analyze the image seen in relation to past experiences; accustomed to seeing real faces, they tend to interpret hollow faces as if they were solid ones. This process is defective in schizophrenic subjects,’ explains an article in Science and Life.But don’t panic if you have trouble seeing the convex part of the mask because it could also mean that you are a genius! According to doctors, schizophrenia and genius aren’t actually that different. It is, however, necessary to distinguish between the two.Geniuses might visualise the image in two ways: that of a healthy person, but also that of a schizophrenic. If they want, they can ‘force’ their brains to no longer see the illusion and instead see the mask as a schizophrenic normally would.And what do you see?