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After reading this article you will learn about the effect of sensory deprivation on human behaviour.
Human behaviour is dependent, to a great extent, on the stimulus conditions that exist in environment. When the individual, with all his sense, is exposed to these conditions, certain psychological processes are initiated. In other words, the entire behaviour of the individual is initiated through his senses.
However, researchers working in the area of sensory psychology extended their studies and brought out some interesting phenomena arising when the senses or sense organs are restricted from getting adequately stimulated. They wondered what an individual would do when placed in an environment which does not contain the kinds of stimulation that are normally encountered in our daily lives.
Imagine, you are isolated and confined in a small room in which there is no light or sound. In addition, you are instructed to lie on a bed as still and quiet as possible. This strange condition with the absence of stimulation is termed as sensory deprivation.
The problem of sensory deprivation is not new; it has existed since pre-historic times in the form of solitude or social isolation and has been experienced by explorers, prisoners, writers etc. Most of us have heard about this referred to as solitary confinement, cabin fever etc.
Scientists working in the area of sensory psychology have tried to study this problem experimentally and attempted to trace the effect of such experiences on various aspects of human behaviour like perception, learning, thinking and other related phenomena.
In an experiment conducted by Lilly, Shirley and others in their attempt to achieve absolute reduction of sensory stimulation, a water tank was used in which subjects were immersed with a blocked-out face mask attached to a breathing tube.
The general construction of the room in which the tank was placed was such that there was a marked reduction of light, sound, vibration, odour and taste stimuli. The large tank of water provided a simulated state of weightlessness and a uniform tactile field. The water in the tank flowed continuously and was maintained at a temperature of approximately 35.5°C.
When the subject was immersed in the water, he was instructed to inhibit body movements as much as possible. By carefully placing appropriate weights as materials with low stimulating properties around the mask and the body, neutral buoyancy of the body was achieved. The mask and air-control system permitted effortless breathing.
There was no reduction in oxygen. Microphones were suspended above the tank, so that the sounds and reports of the subjects could be monitored. In some experiments, he was instructed to communicate his experience with minimal distortions and omissions during the test run; in other experiments the subjects reported after the test run.
Vernon adopted a more severe restriction of conditions in his experiments. The subjects were placed in a basement room that was both light-proof and soundproof. Sound proofing was obtained by constructing a room floating within a room.
The outer room was essentially a shell of sixteen-inch reinforced concrete and the inner room had walls eight-inches thick which were separated from the outer room by a five-inch air gap. The floor of the inner room was specially constructed to prevent sound vibration from entering the room through contact with the ground.
Noises generated in the inner room were partially absorbed by the soft fibre board which lined the walls and the ceiling. There was no illumination in the inner room. The subjects were instructed to be as quiet as possible and not to generate any sound such as talking, singing and so on.
A microphone was concealed in the inner room which provided means for monitoring the subject’s activities. Each subject was also instructed that he could terminate his participation in the sensory deprivation experiment simply by pushing a panic button located within easy reach in the inner room.
In another experiment monotonous conditions in the sensory environment were introduced rather than reducing the levels of stimulation. Waxier and others, in their experiment, had the subject placed in a polio tank type respirator with a specially built mattress. His arms and legs were encased in rigid but comfortable cylinders which inhibited movements and minimised tactile impressions.
Since the subject was lying on his back, it was impossible for him to see any part of his body. The subject breathed for himself; the vents of the respirator remained open. To provide a constant masking noise that was monotonous and dull, the motor of the respirator was kept running.
The only light in the room was from an electrical source and was maintained at a constant and minimal level. The subject was prevented, by means of a large hood placed above the head, from seeing anything except the front of the tank, the blank white walls and the ceiling. It was made possible for the subject to drink from a feeding tube placed near his mouth.
A bedpan was provided at his request. The subject was informed that the experiment would last for up to thirty six hours, but it could be terminated at any point if he so desired. His verbal responses, motor activity, sleep and wakefulness patterns, cardiac, respiratory and other activities were recorded. The outcome of such experiences was something unusual. Some of the general findings will be mentioned here.
Almost all the subjects displayed gross disturbances of psychological processes. The effects of these disturbances lasted for several minutes to hours. Some of the perceptual disturbances reported were – objects in the visual field were felt to be moving; there was marked decrease in shape and size constancy, the walls of the room seemed to be moving in and out; plain surfaces seemed to be swayed or curved; parallel lines seemed to have a barrel shape; and movements of the subjects were accompanied by a corresponding apparent movement in perceived objects.
Nearly every experimental subject who experienced sensory deprivation for a relatively long period of time reported having difficulty in thinking coherently and in concentrating. Some were unable to count consecutively more than twenty or thirty numbers. Others found it extremely difficult to talk.
Many subjects volunteered for the sensory deprivation experiments with the expectation that this would be an excellent time for concentration and for attempting to resolve various types of personal and academic problems. The subjects claimed that they were able to concentrate and think more clearly during the first few hours of the experiments when they were not asleep.
Later, they reported extreme difficulty in thinking. Many ideas or problems could be initiated but no orderly thought processes could be sustained for any long period of time. When the thought process became disordered, the subjects engaged in extensive day dreaming.
The results of a few studies suggested that performance on certain types of intellectual tasks was impaired. However, there is no general loss of cognitive functioning. A decrease in arithmetic reasoning, problem-solving abilities and recognition was reported. Many subjects reported hallucinatory experiences in the visual, auditory and some aesthetic modalities.
Without further elaboration it becomes explicit from the discussion that when environmental conditions are manipulated and sensory stimuli are restricted, it is likely to impair the individual’s physiological functioning, and may lead to neurotic behaviour. Our discussion of the above experiments on sensory deprivation brings out clearly the importance of sensory experience for normal growth and development.
Sensory deprivation results not only in loss or under-development of specific sensory functions but also has an impact on the total growth and adjustment of the organism. It has also been shown that in some cases where the deprivation occurs in early years and in severity, the resulting loss or disturbance may become irreversible. One can, therefore, appreciate the relevance and significance of environmental stimulation in all aspects of life.
In the above, we have discussed the basic nature and characteristics of our sensory experience. An attempt has been made to explain the physiological basis, the characteristics and the mechanisms of the various sensory experiences. Sensory experiences form the basis of our awareness and interaction with the environment.
They are the raw materials out of which other cognitive experiences like perceptions, learning, concepts etc. originate. Our ability for normal perception, learning and thinking depends on adequate sensory experience. In recent years, the importance of adequate sensory motor experience for normal psychological development has increasingly attracted the attention of researchers.
A lot of research has been carried out in this area, which is of importance for understanding human behaviour under a number of conditions like space vehicles, under-water conditions etc. Prolonged sensory deprivation has been found to affect the normal cognitive development of individuals. Because of this we realise the importance of adequate sensory stimulation.
Sometimes our sensations do not function normally. In some individuals there is a total loss of some sensations. This is known as a condition of anesthesia. Some individuals, on the other hand, are found to suffer from low or subnormal sensitivity. This is called partial anesthesia. Some, on the other hand, experience a high degree of sensitivity.
This is called hyper-anesthesia. Often these conditions result from physiological or organic causes. But there are also instances where such conditions result from psychological causes. This is very commonly seen among patients who suffer from hysteria. Many hysterics show symptoms of blindness, deafness and other forms of sensory disorders. These are called functional sensory disorders. These conditions arise without any basic organic or physiological damage or injury. Such conditions are cured by psychological treatment.
It may be observed that it is very rare that one experiences, sensations in a pure form. Most of the experiences to which we referred as sensations are really perceptions. The experience of perception implies that the sensory experience had been organised or interpreted. This process takes very little time.