Sensory Deprivation

An experimental procedure involving prolonged reduction of sensory stimuli.

Sensory deprivation experiments of the 1950s have shown that human beings need environmental stimulation to function normally. In a classic early experiment, college students lay on a cot in a small, empty cubicle nearly 24 hours a day, leaving only to eat and use the bathroom. They wore translucent goggles that let in light but prevented them from seeing any shapes or patterns, and they were fitted with cotton gloves and cardboard cuffs to restrict the sense of touch. The continuous hum of an air conditioner and U-shaped pillows placed around their heads blocked out auditory stimulation.

Initially, the subjects slept, but eventually they became bored, restless, and moody. They became disoriented and had difficulty concentrating, and their performance on problem-solving tests progressively deteriorated the longer they were isolated in the cubicle. Some experienced auditory or visual hallucinations. Although they were paid a generous sum for each day they participated in the experiment, most subjects refused to continue past the second or third day. After they left the isolation chamber, the perceptions of many were temporarily distorted, and their brain-wave patterns, which had slowed down during the experiment, took several hours to return to normal. The intensity of the discomfort these volunteers experienced helps explain why solitary confinement is often regarded as the most severe form of punishment in prisons.

The deterioration in both physical and psychological functioning that occurs with sensory deprivation has been linked to the need of human beings for an optimal level of arousal. Too much or too little arousal can produce stress and impair a person's mental and physical abilities. Thus, appropriate degrees of sensory deprivation may actually have a therapeutic effect when arousal levels are too high. A form of sensory deprivation known as REST (restricted environmental stimulation), which consists of floating for several hours in a dark, soundproof tank of water heated to body temperature, has been used to treat drug and smoking addictions, lower back pain, and other conditions associated with excessive stress.