Sensory deprivation
Sensory deprivation is the reduction of sensory input into the human system, whether naturally occurring or induced. Simple artificial systems can reduce visual and auditory input while more complex designs can also reduce olfactory, tactile, thermoceptive, gustative and 'gravitational' sensations. Sensory deprivation has been used in various alternative medicines, for torture or punishment, and in psychological experimentation.
A common sensory deprivation system is termed a floatation tank or chamber. The subject is suspended in the sound-proof and light-proof tank which is filled with skin-temperature salt water. Correctly restrained and positioned, a subject will be unable to experience many common sensory inputs. Hallucinations, out of body experiences, anxiety, depression, and unusual thoughts are a common reaction to extended sensory deprivation, suggesting a deep human need for almost constant stimulus. Shorter term exposure may be relaxing and other benefits are claimed but not confirmed by mainstream science.
Richard Feynman, a famous physicist, writes about his experiences with sensory deprivation in a floatation tank in one of his popular books, Surely You're Joking, Mr. Feynman!.
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