A variety of studies and experiments have explored the effects of certain variables on consciousness. For instance, it is important to ascertain the way in which variables that increase memorability in turn influence metamemory. Results have been inconsistent. However, it was found that when experimenters directed subjects to remember some items and forget others, there was an increase in recalling those items that experimenters were directed to remember. There was, nevertheless, no effect on the accuracy of what was remembered.
Sleep and dreams, hypnosis, and other altered states have provided another intriguing area of study for those interested in consciousness. The relationship of naps to alertness later in the day has proved of great interest to psychologists. In one study, nine healthy senior citizens, seventy-four to eighty-seven years of age, experienced nap and no-nap conditions in two studies each. Napping was for one and one-half hours, from 1:30 to 3:00 p.m. daily. The no-nap condition prohibited naps and encouraged activity in that period. Various tests were used to measure evening activity as well as record sleep. Aside from greater sleep in the twenty-four-hour period for those who had the ninety-minute nap, there was no difference on any other measure.
The threat simulation theory of dreaming holds that dreams have a biological function to protect the dream self. This dream self behaves in a defensive fashion. An empirical test of this theory confirmed the predictions and suggests that the theory has wide implications regarding the functions of consciousness.
The study of consciousness, then, has elucidated understanding of perception, memory, and action, created advances in artificial intelligence, and illustrated the philosophical basis of dissatisfaction with the dualistic separation of mind and body. Electrical correlates of states of consciousness have been discovered as well as structures in the brain stem that regulate the sleep cycle. Other studies have looked at neural correlates in various states such as wakefulness, coma, the persistent vegetative state, the "locked-in" syndrome, akinetic mutism, and brain death. There are many other areas of consciousness in which neuroscience has made major advances.
An important problem neglected by neuroscientists is the problem of meaning. Neuroscientists are apt to assume that if they can see that a neuron's firing is roughly correlated with some aspect of the visual scene, such as an oriented line, then that firing must be part of the neural correlate of the seen line. However, it is necessary to explain how meaning can be ex pressed in neural terms as well as how the firing of neurons is connected to the perception of a face or person.
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HYPNOTISM is by no means a new art. True, it has been developed into a science in comparatively recent years. But the principles of thought control have been used for thousands of years in India, ancient Egypt, among the Persians, Chinese and in many other ancient lands. Miracles of healing by the spoken word and laying on of hands are recorded in many early writings.