This black and white image may looks like a random pattern of blotches, but scroll down and look at the photo below and stare at this one again. It’s likely you will start to make sense of it and see a similar image of a baby. It’s this ability that scientists believe could help explain why some people are prone to hallucinations
This black and white image may looks like a random pattern of blotches, but if you glance at the photo below, it’s likely you will start to make sense of it and see a similar image of a baby.
It’s this ability that scientists believe could help explain why some people are prone to hallucinations, which are often associated with psychotic disorders.
In other words, they think hallucinations may be caused by a natural process used by the brain to make sense of the world and that most of us experience them at one point or another.
Visions and sounds that do not exist can be generated by the brain's habit of predicting what it expects to experience, filling in missing gaps in reality, the research by scientists at the Universities of Cardiff and Cambridge shows.
Some people with mental illnesses experience psychosis, which is sometimes a frightening loss of contact with reality where people may see, feel, smell and taste things that are not actually there - so-called hallucinations.
Most of us have experienced a mild hallucination before, by thinking we have seen or hear something that isn't really there.
The researchers explored the idea that hallucinations arise due to an enhancement of our normal tendency to interpret the world around us by making use of prior knowledge and predictions.
Scientists think hallucinations may be caused by a natural process used by the brain to make sense of the world and that most of us experience them at one point or another. An image of a baby is shown, which the blotchy black and white image above. The pair are similar to those used in the study
To make sense of our surroundings, we use appropriate information about the world around us, such as our location, but when this isn't possible, we have to interpret potentially ambiguous and incomplete information from our senses.
The brain combines this puzzling information with prior knowledge of the environment to make sense of a situation.
For example, a pet owner entering a room in their house will have little difficulty interpreting a fast-moving shape as their cat, even if they only catch a glimpse of a blur.
'Vision is a constructive process – in other words, our brain makes up the world that we “see,” said Dr Christoph Teufel from the School of Psychology at Cardiff University.
'It fills in the blanks, ignoring the things that don't quite fit, and presents to us an image of the world that has been edited and made to fit with what we expect.’
Professor Paul Fletcher from the Department of Psychiatry at the University of Cambridge added: 'Having a predictive brain is very useful – it makes us efficient and adept at creating a coherent picture of an ambiguous and complex world.
'But it also means that we are not very far away from perceiving things that aren’t actually there, which is the definition of a hallucination.
'In fact, in recent years we've come to realise that such altered perceptual experiences are by no means restricted to people with mental illness.
They are relatively common, in a milder form, across the entire population. Many of us will have heard or seen things that aren’t there.’
In order to see whether predictive processes contribute to the emergence of psychosis, the scientists worked with 18 volunteers who had been referred to a mental health service run by the NHS Cambridgeshire and Peterborough Foundation Trust.
They examined how these people – along with a group of 16 healthy volunteers – were able to use predictions in order to make sense of ambiguous, incomplete black and white images, similar to the one of the baby.
They were asked to look at the images and say if they contained a person or not.
At first, they found the task difficult, but then they were shown a series of non-distorted colour images from which the abstract monochrome ones had been derived.
They predicted that since hallucinations may come from a greater tendency to superimpose one’s predictions on the world, people prone to seeing things would be better at identifying correct features in the abstract images.
The study, published in the journal PNAS, shows people with early signs of psychosis performed better than the healthy control group.
The result suggests people from the clinical group were relying more strongly on the information that they had been given to make sense of the ambiguous pictures.
When the same experiment was conducted with a larger group of 40 members of the general public, a range of ability was seen. Individuals who had higher scores in tests for psychosis-proneness - but no psychotic symptoms as such - stood out.
Naresh Subramaniam from the Department of Psychiatry at the University of Cambridge explained: 'These findings are important because they tell us that the emergence of key symptoms of mental illness can be understood in terms of an altered balance in normal brain functions.
'Importantly, they also suggest that these symptoms and experiences do not reflect a ‘broken’ brain but rather one that is striving – in a very natural way – to make sense of incoming data that are ambiguous.'
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