Sensory deprivation can produce hallucinations in only 15 minutes

Robert Fludd's depiction of perception (1619). Image: Wikimedia Commons

( -- A new study has found that even a short period of sensory deprivation is enough to produce hallucinations even in people who are not normally prone to them.

The 19 volunteers in the study were chosen from over 200 applicants who all completed a Revised Hallucinations Scale questionnaire, which is designed to determine if people are predisposed to hallucinations. The researchers selected nine subjects from applicants who scored in the upper 20th percentile and 10 from the lower 20th.

The researchers, from the University College, London, placed the volunteers one at a time into an anechoic chamber. The chamber had thick outer walls, inner walls of metallic acoustic panels, and a layer of fiberglass sandwiched between them, and completely dampened sound to below the threshold of hearing, and also blocked out all light.

The subject sat in a padded chair in the sensory deprivation room for 15 minutes, during which time many of the subjects reported hallucinations, a depressed mood or paranoia. The volunteers could have used the panic button to be immediately released from the chamber, but none did. After the experiment they completed a Psychotomimetic States Inventory test to determine if they had experienced hallucinations or other experiences resembling psychoses. The test was developed originally to study the experiences of users of recreational drugs.

Of the nine volunteers who had high scores on the first questionnaire, almost all reported experiencing something "very special or important" while inside the chamber. Six saw objects that were not there, five had hallucinations of faces, four reported a heightened sense of smell, and two felt there was an evil presence in the chamber with them.

The 10 volunteers who had lower scores on the questionnaire, indicating they were less prone to hallucinations, still reported experiencing hallucinations and , but to a lesser degree than the other group.

One of the researchers, psychologist Oliver Mason, said the results of the experiment support the idea that hallucinations are produced through what the scientists call faulty source monitoring: the brain misidentifies the source of its own thoughts as arising from outside the body. Mason was not surprised by the rather dramatic results after such a short time, saying the psychosis-inducing effect of sensory deprivation is analogous to the effect of drugs such as cannabis and ketamine, especially in those prone to psychoses. The findings may be important because they suggest that mental illness and normality occur on a continuum.

Future research planned includes studying the effects of sensory deprivation on recreational drug users and people with schizophrenia.

The results of the study are published in the October edition of the Journal of Nervous and Mental Disease.

More information: Journal of Nervous and Mental Disease, The psychotomimetic effects of short-term sensory deprivation, Mason OJ, Brady F.; 197(10):783-5

via Wired

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Citation: Sensory deprivation can produce hallucinations in only 15 minutes (2009, October 23) retrieved 14 October 2019 from
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User comments

Oct 23, 2009
"The findings may be important because they suggest that mental illness and normality occur on a continuum."

OMG! It's not "us and them" anymore! There are people in between! I better spy on *all* of my neighbours!!

Seriously, it's never even crossed my mind that doctors *still* think in black-and-white. Sigh!

Oct 23, 2009
So what's new. This was proven back in the '40's. I can get the same results with a couple of beers.

Oct 23, 2009
Um, their study-room sounds like a good place to chill: Did the gallant researchers probe beyond the initial 'rebound' phase to the point where their stressed-out volunteers managed to relax and be themselves ??

Oct 23, 2009
YESYESYES, I always said that and I am convinced that this is true.

Oct 23, 2009
They call it hallucinations here, however what you're really doing is allowing your perception of existence, of being, to transcend the extreme limitations and burden of physical sensation dependency. Like dreaming except your cognitive ability is still in place.

And this isn't even total sensory deprivation they conducted on these subjects. Private practitioners of sensory deprivation, as a meditative therapy, have what are basically vats of high saline content water kept at body temperature to float their bodies and remove all sensation of touch, in addition to the sound and sight deprivation that was employed above.

If people in such a state experience depression, paranoia, or an evil presence, it's probably because they simply don't know how to handle it or are not right with themselves and if they pursued this practice would probably be happier people in their waking life.

Dimethyltryptamine is the chemical your brain produces which induces this altered state of perception.

Oct 24, 2009
Has anyone considered that perhaps there are things invisible to us that people normally don't think about in their everyday lives. For example, spirits, demonic powers, ghosts, etc. Perhaps these "hallucinations" were not really hallucinations but perhaps a glimpse of what is unknown and/or hidden from us, especially from an environment that these subjects were put in.

For example, when there was a claim that micro-organisms existed people, at first, didn't want to accept it (I'm sure people wanted to label it as "heresy"). However, as people were introduced to the use of the microscope (new technology) people rolled over (they felt as if their traditional way of thinking have been robbed; they're afraid of change), and then accepted it. New technology yielded new scientific research.

In the same way, if the creation of new technology and/or a new model in science that would explain these "hallucinations" would come about, people would again roll over, and humans would advance.

Oct 24, 2009
@BetterByDesign Be careful because I had a post like this deleted by the admins. No Joke. Somehow these guys from physorg have some undisclosed information that nobody has access to. They seem to have proof that all these thinks like God and demons do not exist.

Dec 21, 2009
Experience the Ganzfeld sensory deprivation effect with these easy to make goggles:


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