Read The Story of Psychology Online
Authors: Morton Hunt
The Story of Psychology (95 page)
The James-Lange theory was generally accepted for many years, and by the 1920s, as new techniques of physiological measurement were developed, researchers were able to measure objectively the bodily states James had been able to describe only subjectively. Their aim was to see how specific changes in blood pressure, pulse, and respiration correlated with the emotions the subjects said they experienced.
In the free-wheeling spirit of the time, some of the researchers imposed stresses on their subjects that would be considered outrageous today. A psychologist named Blatz, for instance, told his volunteers that the experiment they were taking part in was a study of heart-rate changes over a fifteen-minute period. Each volunteer was tied in a chair, blindfolded, wired to equipment that monitored pulse, breathing, and skin
conductance, and left alone for a quarter of an hour. After three such sessions during which nothing happened—some subjects actually fell asleep—at some point in the fourth session Blatz threw a switch causing the chair, hinged in front and standing on a trap door, to drop backward. It was smoothly stopped by a door check after falling through a 60-degree arc. The volunteers exhibited a burst of rapid and irregular heartbeat, the abrupt cessation of breathing followed by gasping, and a surge of skin conductance. All reported feeling fear (and, later, either anger or amusement). Presumably, the fall was so sudden and unexpected that there was no anticipatory emotion; as in the James-Lange theory, the fear was the experience of the bodily changes produced by the fall.
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Carney Landis, a psychologist interested in the physiological sources of severe emotional upsets, must have been a remarkable salesman. In the early 1920s, he was able to persuade three volunteers to fast for forty-eight hours, go without sleep for the last thirty-six of them, be hooked up to blood-pressure and chest-expansion monitors, swallow a small balloon attached to a rubber tube to allow gastric contractions to be measured, have a similar device inserted into their rectums, and breathe into an apparatus that measured their carbon dioxide output as an index of metabolic rate—and at that point receive an electric shock as strong as they could bear without struggling until they signaled that they could stand it no longer.
The shock caused the blood pressure to shoot up, the pulse to race and become irregular, and the rectal contractions to cease. (The data on stomach contractions were not consistent.) But despite the volunteers’ commendable suffering for science, the results of the procedure were unclear. Although all three said they felt anger, they had little or no awareness of any specific physiological changes associated with and possibly causing the emotion. The only physical response Landis could find that regularly corresponded to a subjective state was that of surprise. An eye blink and a complex facial-bodily reaction immediately preceded awareness of the emotion and that, at least, was in accord with the James-Lange theory.
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But by 1927 other physiological experiments were yielding powerful evidence that contradicted the theory. They were the work of Walter Cannon (1871–1945), a distinguished investigator and theorist. Cannon was, like John B. Watson and James Gibson, one of those impecunious small-town youths who, though lacking important connections, was able in that era to scale the scientific heights through hard work and genius. He published research papers that attracted wide attention even
before receiving his M.D. at Harvard, and, without any close links such as William James had had to the powers at that university, was appointed its George Higginson Professor of Physiology at the age of only thirty-five.
Although Cannon’s discipline was physiology, he had studied under James and was a friend of Robert Yerkes. It may have been these influences that led him, after years of exploring the control of digestion by the ANS, to turn to the physiology of the emotions. After much investigation, he came to regard the James-Lange theory as thoroughly wrong, and in 1927 he published a historic paper that seemingly demolished it.
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In the paper he offered five kinds of evidence based on his own and others’ research. Of the five, the following three were particularly convincing:
—Visceral changes usually occur one to two seconds after a stimulus, but emotional reactions generally take less time; they therefore precede the physical changes. (Although this was based on laboratory evidence, it is a common experience that immediately after a near-accident we feel fear—after which our heart pounds, we feel weak, we have a strange taste in our mouth, and more.)
—There are some differences among the visceral responses associated with various emotions, but they are not so differentiated or sensitive as to provide distinctive cues for the range of emotions that human beings experience.
—Cannon surgically severed the viscera of cats from the sympathetic nervous system, as C. S. Sherrington, a British physiologist, had previously done with dogs. In both cases all messages from the heart, lungs, stomach, bowels, and other viscera in which, according to James, emotions originate, were cut off from the brain. Nonetheless, wrote Cannon:
These extensively disturbing operations had little if any effect on the emotional responses of the animals. In one of Sherrington’s dogs having a “markedly emotional temperament,” the surgical reduction of the sensory field caused no obvious change in her emotional behavior; “her anger, her joy, her disgust, and when provocation arose, her fear, remained as evident as ever.” And in the sympathectomized cats all superficial signs of rage were manifested in the presence of a barking dog—hissing, growling, retraction of the ears, showing of the teeth, lifting of the paw to strike…
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Yet studies in succeeding decades, down to the present, continued to find evidence that in limited ways the James-Lange theory is correct. Three examples:
—A medical team at the Washington University School of Medicine found in 1969 that injections of lactate (a byproduct of energy metabolism in the cells) produce the physiological symptoms associated with anxiety plus the subjective sensation of anxiety, the latter most strongly in those who are anxiety-prone.
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—In 1966 George Hohmann, a psychologist who was a paraplegic because of a spinal injury, interviewed twenty-five war veterans, all of whom had suffered severed spinal cords two years or more earlier. Hohmann asked them to describe episodes of fear, anger, sexual excitement, and grief experienced both before and since their injuries. They said that, except for grief, their emotions were different since the severing of the spine; there was a decline in quality, a muting or coldness to their feelings. Strikingly, the higher the lesion—and therefore the greater the number of body systems disconnected from the brain—the greater the change. As one man with a cervical (high) lesion said:
I sit around and build things up in my mind, and I worry a lot, but it’s not much but the power of thought. I was at home in bed one day and dropped a cigarette where I couldn’t reach it. I finally managed to scrounge around and put it out. I could have burned up right there, but the funny thing is, I didn’t get all shook up about it. I just didn’t feel afraid at all, like you would suppose.
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—Psychologists have long debated whether emotions are universal or relative; that is, whether people in different cultures feel the same feelings. For more than two decades, Paul Ekman of the University of California, San Francisco, Medical School, and his colleagues have studied the matter. They asked people in different cultures to express six basic emotions (anger, disgust, happiness, sadness, fear, and surprise), and found that their facial expressions were basically similar, though somewhat modified by cultural rules. Both Ekman and his colleagues, and Carroll Izard of the University of Delaware, have shown to people in a number of very different cultures photographs of actors expressing a number of emotions. Almost always, the viewers identified them correctly.
While there are major differences in the cultural situations evoking particular emotions, the evidence strongly suggests that the basic emotions are universal and are accompanied by the same movements of facial muscles.
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This does not prove that physical sensations precede the perception of emotion, as James and Lange posited. But more than a dozen experiments by Ekman and by others have shown that when volunteers deliberately assume the facial expression of a particular emotion, the muscular efforts involved create small but measurable changes in pulse rate, respiration rate, and skin conductance, along with equally small but measurable changes in their feelings.
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Ekman considers these results a feedback effect: the deliberately assumed expression brings about bodily changes, which then create the emotional feeling the person has simulated.
The same principle sometimes enables psychotherapists to alter the emotions of patients. By changing facial expression, posture, and body movements, the patient can to some extent replace a despondent or defeated mood with a more positive and cheerful one.
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Again, this supports the James-Lange theory: What we sense in the body determines our feelings. (Make the experiment yourself. Wreathe your features in a great, sunny grin, hold it for some seconds, and see if you don’t feel at least a modicum of the feeling that should go with it.)
For such reasons, the James-Lange theory survives—or at least is part of the contemporary understanding of the emotions. In recent decades, research by cognitive psychologists and by cognitive neuroscientists has yielded a complex, multifaceted explanation of the interaction between the physical symptoms of emotions and the neural processing of those symptoms and of the stimuli responsible. Which comes first, which produces the other? Each one, at times, depending on all sorts of conditions, and often both in a species of feedback. We will spare ourselves the intricacies for now; the net results suggest that both sides in the debate are right and that the neural systems of emotion and cognition are both independent and interdependent.
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In sum, the somatic theory is a valid but imperfect and limited part of the contemporary answer to the question about the sources of the emotions. Now let us go back to look at other theories explored during the last century that have contributed importantly to today’s view of the matter.
Walter Cannon, whose experimental work called into question the James-Lange theory, offered his own theories of emotion and motivation; each was influential for many years.
His motivation theory—sometimes irreverently referred to as the spit-and-rumble theory—held that peripheral clues are what motivate a creature: a dry mouth will prompt drinking, a rumbling stomach will lead to eating. These clues, sending messages to the ancient part of the brain, there give rise to the drive to seek water or food.
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Ironically, Cannon was thus saying about motivation much the same thing he attacked in James’s theory of the emotions.
But Cannon’s theory of emotions was quite different. He held that peripheral or visceral conditions were not the cause of the emotions but concomitant effects of other causes. In gathering his evidence against the James-Lange theory, he decorticated some animals (removed their cortex), after which it took very little stimulus to elicit a rage reaction from them.
This led Cannon and a Harvard colleague, Philip Bard, to suggest that rage and other emotions originate in the thalamus, a primitive structure in the core of the brain that receives information from sense organs (except the nose) and relays appropriate messages to the cortex and the ANS. The cortex, according to the Cannon-Bard theory, usually controls and inhibits the thalamus, but when the thalamus sends it certain kinds of information—the sight of an enemy, for instance—the cortex relaxes its control. The thalamus then is able to send its emotional messages in two directions: to the nervous system, which produces the visceral responses of emotion and the appropriate behavior, and simultaneously back to the cortex, where the feeling of emotion is produced. Thus, the experience of emotion and its visceral symptoms are parallel effects of the thalamic messages.
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Of Cannon’s two theories, the spit-and-rumble account of drive, though dominant for some time, was eventually demolished by other experimental evidence. In 1939 two research studies used “sham drinking” to test it. A fistula surgically made in a dog’s esophagus drained off water as the dog drank, so that none reached the stomach. Although its mouth was wet, the dog continued drinking copiously without allaying its thirst. Evidently, nothing as simple as dry mouth caused the thirst drive; it came from other and deeper visceral signals, turned into action by the nervous system.
The Cannon-Bard emotion theory, however, was strongly supported, although modified, by later research showing that the ANS, thalamus, and other primitive areas of the nervous system could generate emotions without any input participation by the viscera. In the late 1920s and the 1930s Walter Hess, a Swiss physiologist, inserted electrodes in the rear area of the hypothalamus (a part of the core of the brain located below the thalamus) of a laboratory animal and delivered a weak electrical stimulus; the animal acted enraged. When Hess sent the same current into the forward area of the hypothalamus, the animal became calm and sleepy. Much later, José Delgado, a Spanish neuroscientist, demonstrated this hypothalamic control of rage with Iberian flair. He implanted an electrode in the forward area of a bull’s hypothalamus and then entered a bullring holding a control box that would send an electrical impulse through the electrode. The bull was released into the ring, saw Delgado, grew enraged, and charged. Delgado, unflinching, pushed the button, and the bull halted and turned away.
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At Yale in the 1950s, Delgado and several colleagues did equally impressive, if less theatrical, research with electrode implantations in rats and cats. By sending a weak current into a cat’s or rat’s amygdala—a part of the “limbic system” or ancient mammalian brain, a series of structures located between the thalamus and the cortex—they produced fear behavior. Later, Delgado and others did so with human patients during brain surgery. When one patient was receiving the current, he said he felt as if he had just been missed by a car, another as if “something horrible was about to happen” to her. The feelings ceased as soon as the current was turned off.
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