Hallucinations: how they emerge

Credit: Cardiff University

Take a look at the image above. It probably looks like a meaningless pattern of black and white blotches.

But now take a look at the image below and then return to the picture: it’s likely that you can now make sense of the black and white image.

It is this ability that scientists at Cardiff University and the University of Cambridge believe could help explain why some people are prone to hallucinations.

Credit: Cardiff University

Researchers are exploring the idea that hallucinations come from our normal tendency to interpret the world around us by making use of predictions.

Our brains fill in any missing information by using past experiences.

A bewildering and often very frightening experience in some mental illnesses is psychosis – a loss of contact with external reality. Hallucinations can accompany psychosis.

Researchers showed black and white images to individuals showing the very early signs of psychosis along with healthy volunteers.

They were asked whether or not the image contained a person.

They were then shown a series of full colour original images, including those from which the black and white images had been derived.

The researchers reasoned that, since hallucinations may come from a greater tendency to superimpose one’s predictions on the world, people who were prone to hallucinations would be better at using this information.

They found a larger performance improvement in people with very early signs of psychosis in comparison to the healthy control group.