Out of LSD? Just 15 Minutes of Sensory Deprivation Triggers Hallucinations

By | October 22, 2009


You don’t need psychedelic drugs to start seeing colors and objects that aren’t really there. Just 15 minutes of near-total sensory deprivation can bring on hallucinations in many otherwise sane individuals.

Psychologists stuck 19 healthy volunteers into a sensory-deprivation room, completely devoid of light and sound, for 15 minutes. Without the normal barrage of sensory information flooding their brains, many people reported experiencing visual hallucinations, paranoia and a depressed mood.

“This is a pretty robust finding,” wrote psychiatrist Paul Fletcher of the University of Cambridge, who studies psychosis but was not involved in the study. “It appears that, when confronted by lack of sensory patterns in our environment, we have a natural tendency to superimpose our own patterns.”

The findings support the hypothesis that hallucinations happen when the brain misidentifies the source of what it is experiencing, a concept the researchers call “faulty source monitoring.”

“This is the idea that hallucinations come about because we misidentify the source of our own thoughts,” psychologist Oliver Mason of the University College London wrote in an e-mail to Wired.com. “So basically something that actually is initiated within us gets misidentified as from the outside.” Mason and colleagues published their study in October in the Journal of Nervous and Mental Disease.

via Out of LSD? Just 15 Minutes of Sensory Deprivation Triggers Hallucinations | Wired Science | Wired.com.

2 thoughts on “Out of LSD? Just 15 Minutes of Sensory Deprivation Triggers Hallucinations

  1. Sepp

    I wish there was a proper term for this kind of experience that isn’t “hallucination”, as the word has a connotation of false, a fake perception.

    What is likely happening is that those people turn on an extended perception, seeing stuff we don’t normally see, as the visual and aural influx of information from the world around us tends to drown it out.

    We shouldn’t be pointing our finger at people who see things that aren’t in everyone else’s universe, saying they are mentally ill (hallucinating) because those strange perceptions might just be a notch up from what we normally observe. The “mentally ill” are simply more sensitive than most of the rest of us.

    1. Xeno Post author

      Hi Sepp,

      Here is what I currently believe: Dreams are, for the most part, imaginary experiences. The exceptions are that 1) some sensory input does leak in to dreams influencing content. Loud sounds can be incorporated into dreams, for example. And 2) science would disagree with me on this, but also, I believe that some people have, perhaps a few times in their lives, genuine ripples of information from the future. I say this based on my tree dream which I can explain no other way.

      What scientists understand about brains is that everything we experience is our own mental model of the world.

      When we are awake, sensory input feeds into that model, giving us a world made up of body sensation, sights, sounds, tastes, and smells. When we sleep, however, with those inputs cut off, the brain keeps the model working by generating its own internal sensations which we experience as dreams. In addition to rehearsing our mental model, dreams serve another purpose: When we dream we are also consolidating long term memories, that is, we are fitting the day’s experiences into our existing memories.

      Hallucinations you get from a sensory deprivation tank, therefore, are due to the fact that brains naturally generate their own content when you take away input from the real world. You can get visual hallucinations just by cutting a ping pong ball in half and putting each half over your eyes. Same thing happens with “Snow blindness”. People in snow storms hallucinate.

      While it is kind of you to think that people who have waking hallucinations may be visionaries who are above us in their abilities, I think that is not the case.

      I have tinnitus. I experience a very loud high pitched ringing in my ears. This is due to hearing loss. I don’t have super powers. I’m not in tune with another universe that you all can’t hear. My nervous system is simply malfunctioning because it isn’t getting input at those frequencies anymore from my damaged ear.

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