The study, led by Professor Phil Reed of the Department of Psychology, is published in the international peer-reviewed journal, Psychiatry Research and used a unique experimental procedure designed to investigate the nature of hallucinations in people who had no sign of mental illness. 

The religious belief of 100 people was measured, and then they were presented with a computer task, in which they had to identify the presence of words on a screen.  The study measured the number of times that people reported seeing words that were not actually there, and also assessed the types of words that they claimed to see.

The experiment found that people with strong Christian beliefs reported seeing more religious words than those without such beliefs when they were in a context designed to produce religious thoughts. 

For the more religious participants, 93 per cent reported a religious hallucination when they were in a religious context, as opposed to only 50 per cent who reported such a hallucination in a non-religious context. 

In terms of the nature of the falsely reported words, less than 10 per cent were of a religious nature in a non-religious context, but close to 50 per cent of these hallucinated words were of a religious nature when the participants were in a religious context. 

Professor Phil Reed said: “The religious participants had no mental illness and did not hallucinate more often in general than other people, but when they were in a religious context they did claim to see more religious words that simply were not there.”

Previous research has shown that clinically-significant hallucinations are common in schizophrenia, can occur in drug addicts, and in some cases of depression.  However, mild hallucinations (perceiving something to be there when it is not) are a relatively common experience in the general population, with up to 70 per cent of people reporting having had such an experience.  These mild hallucinations are typically concerned with hearing noises that are not present, and they are quite commonly experienced by heavy users of mobile phones as ‘phantom vibrations’. 

Professor Reed said: “We found that over 60 per cent of the people in our sample experienced some false perceptions – or a mild hallucination – so this is quite a normal thing. 

“However, for some people, these false perceptions can be very disturbing indeed – this is when they become a problem, especially when the content of the hallucination has some particularly special meaning to the individual.” 

Previous research has shown that hallucinations often occur in unexpectedly busy or noisy environments, and previous studies have suggested that religious holidays and festivals – such as Easter or Christmas – can be associated with increases in psychotic episodes in the ‘hyper religious’.

“Although we know some things about when these phenomena will occur, we know little about why they take the particular forms that they do, and this is one of the first studies to try to explore what causes the content of these false perceptions,” added Professor Reed.

The paper by Professor Phil Reed and Natasha Clarke, Department of Psychology, Swansea University, is published in the journal Psychiatry Research and can be found at http://dx.doi.org/10.1016/j.psychres.2014.01.006.