At some point in their lives, about 5 percent of the general population experience either hearing voices or seeing things that nobody else sees, according to a new study.
Hallucinations and delusions are more common than previously thought, the study suggests. The most comprehensive ever completed, the study involved more than 31,000 people from 19 countries, said Professor John McGrath of the University of Queensland:
“We used to think that only people with psychosis heard voices or had delusions, but now we know that otherwise healthy, high-functioning people also report these experiences.
Of those who have these experiences, a third only have them once and another third only have two-to-five episodes across their life. These people seem to function reasonably well.
So it’s incredibly interesting that not only is hearing voices more common than previously thought, but it’s not always linked to serious mental illness.”
In the groundbreaking 1976 book The Origin of Consciousness in the Breakdown of the Bicameral Mind, Julian Jaynes hypothesized that originally, all our ancestors heard voices. Voices that generated from the brain’s right hemisphere and percieved by the brain’s left hemisphere. With the rise, Jaynes wrote, of modern consciousness roughly 3000 years ago, these voices became internalized and thus recognized as own own inner thoughts.
Similarly, in his book The Master and His Emissary: The Divided Brain and the Making of the Western World, psychiatrist Iain McGilchrist reviews scientific research into the role of the brain’s hemispheres, and cultural evidence, and he proposes that since the time of Plato the left hemisphere of the brain (the “emissary” in the title) has increasingly taken over from the right hemisphere (the “master”), to our detriment.
Temporary or Permanent?
The new study was a population-based survey that involved approaching randomly selected members of the community, sitting down with them, and conducting a very detailed interview about their mental health.
“These people were representative of the general population, not seeking mental health assistance,” says McGrath.
The study finds that reports of auditory hallucinations are more common in women than men, and they are also more common in people from wealthier countries.
McGrath says the findings could help generate new research into the causes of these isolated symptoms.
“In particular, we are interested in learning why some people recover, while others may progress to more serious disorders such as schizophrenia,” he says. “We need to understand why it’s temporary for some people and permanent for others. We can use these findings to start identifying whether the mechanisms causing these hallucinations are the same or different in both situations.”
Types of Auditory Hallucination
There are three main categories into which the hearing of talking voices can often fall:
- hearing a voice speak one’s thoughts
- hearing one or more voices arguing
- hearing a voice narrating his/her own actions
Other types of auditory hallucination include exploding head syndrome and musical ear syndrome. In the latter, people will hear music playing in their mind, usually songs they are familiar with. Reports have also mentioned that it is also possible to get musical hallucinations from listening to music for long periods of time.
“We need to rethink the link between hearing voices and mental health—it’s more subtle than previously thought.
While people may experience a false perception such as mistakenly hearing their name called out in public, hallucinations and delusions are quite detailed, for example, hearing voices that no one else can hear or a belief that somebody else has taken over your mind.
People should be reassured that there isn’t anything necessarily wrong with them if it happens once or twice, but if people are having regular experiences we recommend that they seek help.”
McGrath JJ, Saha S, Al-Hamzawi A, et al.
Psychotic Experiences in the General Population: A Cross-National Analysis Based on 31 261 Respondents From 18 Countries.
JAMA Psychiatry. May 27, 2015. doi:10.1001/jamapsychiatry.2015.0575.
Photo: Paolo Imbag via Unsplash
Did you like this article? Then you'll really want to sign up for my newsletter. It's delivered several times a week and packed with science news and analysis. Subscribe Here.