Monday, September 25, 2006
Post-Freudian dream theory
The dream theories of Sigmund Freud and Carl Jung were subjective speculations almost totally without empirical support. Not until 1952 was there a major breakthrough in laboratory Investigations of dreams. That was the year Eugene Aserinsky, a graduate student in physiology at the University of Chicago, accidently discovered REM, the Rapid Eye Movements that accompany deep-sleep dreaming.
Aserinsky had attached electrodes near the eyes of his sleeping 10 year-old son Armond. He was surprised to see that the EEG (electroencephalogram) machine was tracing wide swings on its graph paper. Further research by Aserinsky and Nathaniel Kleitman, director of the university's sleep research, made the great discovery that periods of REM were signs of vivid dreaming in contrast to the feeble dreams of NREM (non-REM) sleep.
REM sleep, it soon became apparent, occurs in intervals throughout the night, usually four to six times, each lasting from ten minutes to an hour. Subjects who believed they dreamed rarely, or not at all, were amazed to find they had strong memories of dreams when they were awakened during a REM period. New facts came co light: Nightmares and sleepwalking occur only during NREM sleep. The belief that a long dream could last only a few seconds proved to be a myth. Types of food eaten during the day have no effect on REM dreams. Recordings played during sleep have no influence on learning, although such spurious claims continue to be made today for audiotapes widely advertised, even in a few popular science magazines.
Intensive research on REM sleep was taken up in scores of laboratories around the world. It was discovered that almost all mammals so far tested have REM sleep periods (including bats, moles, and whales) except, curiously, Australia's spiny anteater. Reptiles lack REM sleep, but birds seem to have intervals of REM that last a few seconds while their heads are under their wings. Dogs and cats clearly have REM dreams. You can lift a dreaming cat's eyelids and see the eyeballs dart back and forth.
REM dreaming surely serves some useful function, otherwise why would evolution have Invented it? Exactly what that function is remains a riddle. One plausible argument is that during the night, when it is difficult to hunt for food, mammals began to rest their bodies and minds until the sun arose. Some mammals even hibernate through cold winters. This, however, sheds little light on the function of dreams.
The computer revolution, and the view of AI (Artificial Intelligence) researchers that a brain is nothing more than an organic computer, led inevitably to computer-derived theories of dreaming. One of the earliest papers advocating such a theory was "Dreaming: An Analogy from Computers," in New Scientist (vol. 24, 1964, pp. 577-579). The authors were two British scientists: psychologist and science fiction writer Christopher Riche Evans, and computer expert Edgar Arthur Newman. In 1993 Evans's posthumous work Landscapes of the Night: How and Why We Dream was published. His 1973 book Cults of Unreason contains a major attack on Scientology.
The Evans-Newman theory is that the brain, like a computer, gets cluttered with useless information. just as a computer's memory has to be routinely cleaned of unwanted junk, so too does our brain need periodic scrubbing. Dreams are the process by which the sleeping brain moves information worth preserving into its long-term memory, and erases from short-term memory the trivia that otherwise would clog neural pathways. Why remember such things as the color of the socks you wore yesterday, or what you had for lunch, or everything you said during idle conversation?
As electrical impulses zip around the brain to eliminate such garbage, the pulses activate adjacent neurons to call up patterns that are essentially random. Our unconscious brain does its best to put these images into some sort of coherent scenario, but because they are randomly accessed, the dream story exhibits bizarre nonsense and abrupt transitions like the scenes in Lewis Carroll's two Alice books. For an hour or two every night we go harmlessly insane!
Freud believed that dreams are symbols expressing in heavily disguised form the repressed wishes of the id (unconscious), most of them sexual and going back to childhood. If not disguised, Freud believed, our shocked superego, with its moral imperatives, would wake us up.
Carl Jung discarded what he thought was Freud's overemphasis on repressed sexual desires. In his view dreams reflect "archetypes" -- memory traces inherited from our evolutionary past. Dreams of flying and falling, for example, are genetic memories of ancestors swinging through trees and occasionally dropping to the ground. Terror dreams of being pursued reflect times when our ancestors fled from fierce beasts. For Jung, dreams do not so much conceal as they reveal these ancient memories buried in what he called humanity's "collective unconscious."
Evans and Newman have no use for either Freud or Jung. Dreams, they argue, are essentially nonsense, though of course influenced by hopes and fears, and by night events such as sounds, smells, temperature, drafts, bodily distresses, and so on. Our brain filters out accustomed noises, such as rain, the hum of an air conditioner, or a television set left on, but sudden, unusual sounds, such as a baby's cries, a thunderclap, or a ringing phone, either wake us or are incorporated into a dream. If we are thirsty we may dream of drinking; if hungry we may dream of eating. If our bladder is full, we may dream of urinating. If our face is sprayed with water, we may dream of taking a shower.
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