Experts at Cardiff University believe that they have come close to explaining the phenomenon of a tendency to hallucinations. Scientists worked with colleagues at the University of Cambridge to study the intellectual nature of the brain.
They relied on the hypothesis that hallucinations are a side effect of the brain's ability to interpret the world around it using prior knowledge and guesses. The study examined how the brain of people suffering from psychosis creates an image of the world.
The study, the results of which were published in the journal Proceedings of the National Academy of Sciences, studied 18 people with early signs of psychosis. The control group consisted of 16 healthy volunteers.
Each of the volunteers was asked to interpret the black and white images - however, in most cases, almost everyone saw only spots. They were then shown the original full-color image to improve the brain's ability to understand ambiguous images.
As it turned out, people with early signs of psychosis showed increased performance in interpretation (compared with healthy controls).
“These results are extremely important because they help us understand the key symptoms of mental illness in terms of altered balance of normal brain function,” says Naresh Subramaniam of the University of Cambridge. "These symptoms and experiences are likely not reflecting a breakdown in the brain, but rather its desire to understand ambiguous data in a very natural way."
Scientists say that most people can understand the picture above only after they see its full color version. This ability of the brain to fill in the gaps appears to explain why some people suffer from hallucinations.
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“Visual perception is a constructive process,” says one of the study's authors, Dr. Christoph Teufel of Cardiff University. “In other words, our brains 'make up' the world we see. He fills in the blanks, ignoring what is not at all suitable, and provides us with a seemingly 'edited' image of the surrounding reality that meets our expectations."
For example, a person walking through his house in the twilight can see a black spot moving quickly across the floor, but his brain already understands that it is a cat. Sensory information is minimal - preliminary knowledge does the main work.
"A developed brain allows us to create a holistic picture of an ambiguous and complex world," says Professor Paul Fletcher of the University of Cambridge. “But it also means that he can sometimes“slip”things on us that don't really exist - that's how hallucinations arise. By the way, changes in perception are characteristic not only of people with mental illness: in a milder form, they are found in the majority."