Sensory deprivation is the deliberate reduction or removal of stimuli from one or more of the senses. Simple devices such as blindfolds or hoods and earmuffs can cut off sight and hearing respectively, while more complex devices can also cut off the sense of smell, touch, taste, thermoception (heat-sense), and 'gravity'. Sensory deprivation has been used in various alternative medicines and in psychological experiments (e.g., see Isolation tank), and for torture or punishment.
Though short periods of sensory deprivation can be relaxing, extended deprivation can result in extreme anxiety, hallucinations, bizarre thoughts, depression, and antisocial behavior.
An isolation tank is a lightless, soundproof tank in which subjects float in salty water at skin temperature. They were first used by John C. Lilly in 1954 in order to test the effects of sensory deprivation. Such tanks are now also used for meditation, prayer, relaxation, and in alternative medicine.
Isolation tanks were originally called sensory deprivation tanks. They were renamed because it was found that the terminology of "sensory deprivation" negatively prejudiced people prior to experiencing the use of the device. Dr. Peter Suedfeld and Dr. Roderick Borrie of the University of British Columbia began experimenting on the therapeutic benefits of this technique in the late 1970s. They renamed the technique Restricted Environmental Stimulation Therapy (REST) or Flotation REST.
A therapeutic session in a flotation tank typically lasts an hour. For the first forty minutes it is reportedly possible to experience itching in various parts of the body (a phenomenon also reported to be common during the early stages of meditation). The last 20 minutes often end with a transition from beta or alpha brainwaves to theta, which typically occur briefly before sleep and again at waking. In a float tank the theta state can last for several minutes without the subject losing consciousness. Many use the extended theta state as a tool for enhanced creativity and problem-solving or for superlearning. Spas sometimes provide commercial float tanks for use in relaxation. Flotation therapy has been academically studied in the USA and in Sweden with published results showing reduction of both pain and stress. The relaxed state also involves lowered blood pressure and maximal blood flow.
The five techniques of wall-standing; hooding; subjection to noise; deprivation of sleep; deprivation of food and drink were used by the security forces in Northern Ireland in the early 1970s. After the Parker Report of 1972 these techniques were formally abandoned by the United Kingdom as aids to the interrogation of paramilitary suspects.
The Irish Government on behalf of the men who had been subject to the five methods took a case to the European Commission on Human Rights (Ireland v. United Kingdom, 1976 Y.B. Eur. Conv. on Hum. Rts. 512, 748, 788-94 (European Commission of Human Rights)). The Commission stated that it "considered the combined use of the five methods to amount to torture".This consideration was overturned on appeal. In 1978 in the European Court of Human Rights (ECHR) trial "Ireland v. the United Kingdom" ruled that the five techniques "did not occasion suffering of the particular intensity and cruelty implied by the word torture ... [but] amounted to a practice of inhuman and degrading treatment", in breach of the European Convention on Human Rights.
It is on record in the ECHR judgment that:
These methods, sometimes termed "disorientation" or "sensory deprivation" techniques, were not used in any cases other than the fourteen so indicated above. It emerges from the Commission's establishment of the facts that the techniques consisted of:''
(a) wall-standing: forcing the detainees to remain for periods of some hours in a "stress position", described by those who underwent it as being "spreadeagled against the wall, with their fingers put high above the head against the wall, the legs spread apart and the feet back, causing them to stand on their toes with the weight of the body mainly on the fingers";
(b) hooding: putting a black or navy colored bag over the detainees' heads and, at least initially, keeping it there all the time except during interrogation;
(c) subjection to noise: pending their interrogations, holding the detainees in a room where there was a continuous loud and hissing noise;
(d) deprivation of sleep: pending their interrogations, depriving the detainees of sleep
(e) deprivation of food and drink: subjecting the detainees to a reduced diet during their stay at the center and pending interrogations.
Solomon, P. et. al. (eds.) (1961) Sensory deprivation. Harvard U Press. Goldberger, L. (1966). Experimental isolation: An overview. Am. J. Psychiat. 122, 774-782. Zubek, J. (ed.) (1969). Sensory deprivation: Ffiteen years of research. Appleton Century Crofts.
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