The Story of Psychology

by Morton Hunt

  But in the laboratory, Pavlov was practical, perfectionist, and systematic. He expected his assistants to live up to his standards, and castigated or fired those who fell short in any way, whatever the reason. During the Revolution (with which, for many years, he had no sympathy, though eventually he became a supporter of the system), one of his employees arrived late. When Pavlov upbraided him, the man said there had been street fighting en route and he had been in danger of losing his life, but Pavlov angrily replied that that was no excuse and that devotion to science should supersede all other motives. According to some accounts, he sacked the man.

  That was long after Pavlov had become successful. In 1891, at the age of forty-two, he was at last appointed professor at the St. Petersburg Military Academy, and a few years later professor at St. Petersburg University. With this solid footing, he was able to organize the Institute of Experimental Medicine, the laboratory in which he conducted his research for forty years. His work during the 1890s was on digestion, which he studied by surgically creating in the stomach of laboratory dogs a little pouch or separate compartment with a fistula implanted in it. This enabled him to observe the gastric reflex (the secretion of gastric juices when the dog began to eat) without the contaminating presence of food. His findings won him a Nobel Prize in medicine in 1904, and in 1907 he reached the height of scientific prestige in Russia when he became an academician, or full member, of the Academy of Sciences.

  Sometime between 1897 and 1900, in the course of his gastric-reflex research, Pavlov became aware of an odd and annoying phenomenon: the dogs would secrete gastric juices and saliva at times other than feedings—for instance, when they saw or heard their keeper shortly before a regular mealtime. At first Pavlov regarded this as a nuisance, since it interfered with the data on the quantities of digestive secretions. But he recognized that there must be an explanation for the production of such fluids when there was no food in the dog’s mouth or even nearby. An obvious one was that the dog “realized” that mealtime was near and these thoughts produced the secretions, but the resolutely antipsychological Pavlov would have nothing to do with such subjective speculations.

  Though reluctant to do research on the matter, he finally decided he could look into it, since in his opinion it was an entirely physiological phenomenon—a “psychical secretion” due to a reflex in the brain caused by the stimulus of the sight or sound of the person who usually brought food. In 1902 he began to study how and when such a stimulus, inherently unconnected to the glandular response, was capable of causing it, and he spent the rest of his life investigating the phenomenon.

  Although Pavlov was an expert surgeon, he spared himself the labor of creating stomach pouches for this research. Since the dogs produced saliva as well as gastric juices at the sight of their keepers, it was enough to implant a simple fistula in one of the salivary glands and hook this up to a collecting and recording device. The dogs were trained to stand still on a table, and were praised, petted, and fed for doing so. Eager to please, they would jump onto the table without being told to and patiently remain there, loosely harnessed in place and attached to equipment. The harness was necessary to prevent disruption of the apparatus, a rubber tube connecting the fistula to a collecting vessel and a recording drum. The dogs faced a wall with a window in it; directly in front of them, inside the experimental chamber, was a bowl into which food could be mechanically dropped.

  As soon as a dog had food in its mouth, its saliva began to flow; since this was a response that required no training, Pavlov called the food an “unconditioned stimulus” and the salivary response an “unconditioned reflex.” The matter to be studied, however, was the link between a neutral stimulus and the same reflex. Typically, the experimenter, out of sight so as not to be a signal to the dog, would make a sound—ring a bell, buzz a buzzer—and would cause food to drop into the bowl anywhere from five to thirty seconds later. At first, the sound of the bell or buzzer would produce only a normal reflex—the pricking-up of the dog’s ears—but no salivary response. But after a number of these sequences, the sound alone would cause the dog’s saliva to start flowing. In Pavlov’s terms, the sound had become a “conditioned stimulus” to salivation, which had become a “conditioned reflex” to the sound.

  Pavlov and his assistants ran many variations of this experiment. Instead of a sound, they would flash a light or rotate an object the dog could see through the window, manipulate apparatus that touched the dog or tugged on a part of its harness, change the length of time between the neutral stimulus and the delivery of food, and so on. In all cases, neutral stimuli could be made into conditioned ones, but with varying degrees of ease; a neutral odor (not of food) might require twenty or more pairings to become a conditioned stimulus, while the rotation of an object in the dog’s view might take only five pairings, the sounding of a loud buzzer only one.11

  A psychologist would have called the conditioning process associative learning, but Pavlov explained it in physiological terms. Acknowledging indebtedness to his mentor, Sechenov, and to Descartes, the first to offer a reflex theory, he theorized that an unconditioned response, such as salivating on taking food into the mouth, was a brain reflex: A direct connection existed between the sensory and motor nerves in the spine or lower brain centers. In contrast, a conditioned response, such as salivating at the sound of a bell or other formerly neutral stimulus, was the result of new reflexive pathways created by the conditioning process in the cortex of the brain.

  Pavlov developed this theory of localized brain reflexes in great detail to fit his findings about conditioning. But it was largely ignored except in the Soviet Union, and in America was soon conclusively disproven by the psychologist Karl Lashley, who removed different areas and amounts of cortex from rats, then had them learn mazes, and found that their loss of ability to learn was related not to the destruction of any particular cortical area but to the total amount destroyed.12

  The fate of Pavlov’s physiological theory, however, in no way diminished the enthusiastic acceptance of his laboratory data and laws of conditioning as a major addition to psychological knowledge. These were some of his more noteworthy findings:

  Timing: The sequence of the stimuli is critical. Only if the neutral stimulus precedes the unconditioned reflex does it become a conditioned stimulus, capable of eliciting the reflex. In one experiment, an assistant gave a dog food and five to ten seconds later turned on a loud buzzer; even after 374 such pairings, the buzzer alone did not bring about salivation. When he sounded the buzzer before giving the dog food, a single pairing was enough to make it a conditioned stimulus.13

  Extinction: Unlike an unconditioned reflex to an unconditioned stimulus, the connection between a conditioned stimulus and a conditioned reflex is impermanent. If the conditioned stimulus is repeatedly presented without reinforcement (food), the salivary response weakens and eventually disappears.

  Generalization: If a dog was presented with a stimulus similar to, but somewhat different from, a stimulus it had become conditioned to—for instance, a tone higher or lower than the one paired with food—the dog would salivate, but less strongly than in response to the conditioned tone. The greater the difference between tones, or between any conditioned stimulus and a related stimulus, the weaker the response. The dog was, in effect, generalizing from its experience and expecting similar experiences to yield similar results.

  Differentiation: After a dog had been conditioned to salivate on hearing a given tone and also on hearing another tone some notes lower, if the first tone was then always reinforced by food but the second one never was, the dog would gradually cease to salivate in response to the second tone. The dog had learned to “differentiate”—the term more often used by English and American psychologists is “discriminate”—between the stimuli.

  Experimental neurosis: In seeking to determine the limits of his dogs’ ability to discriminate, Pavlov unexpectedly precipitated in them something resembling a nervous breakdown. In one historic st
udy, a dog learned to discriminate between a circle flashed on a screen, always followed by food, and an elongated ellipse flashed on the screen, never followed by food. When the dog’s salivating at the sight of the circle and failure to salivate at the sight of the ellipse were well established, the assistant began changing the shape of the ellipse, making it ever more nearly circular. The dog kept learning to discriminate between the circle and the rounder ellipses until the ratio of the axes of the ellipse was 7:8. The assistant then tried an even rounder ellipse whose axes had a ratio of 8:9, but at that point, Pavlov later wrote,

  the hitherto quiet dog began to squeal in its stand, kept wriggling about, tore off with its teeth the apparatus for mechanical stimulation of the skin, and bit through the tubes connecting the animal’s room with the observer, a behavior which never happened before. [Later,] on being taken into the experimental room the dog barked violently, which was also contrary to its usual custom; in short, it presented all the symptoms of a condition of acute neurosis.14

  Only after long rest and careful treatment did the dog recover enough to tolerate experiments in easier differentiations.

  286 The Story of Psychology

  Pavlov believed that he had identified the fundamental unit of learning in animals and human beings. All learned behavior, he said, whether acquired in school or outside it, was nothing but “a long chain of conditioned reflexes” whose acquisition, maintenance, and extinction were governed by the laws he and his assistants had discovered. His ideas profoundly influenced Russian psychology from early in the century until the 1950s, but in the West remained largely unknown for some years, even though Pavlov had mentioned conditioning in his 1904 Nobel award address.

  In 1908 Robert Yerkes (who would later direct the development of the Army Alpha and Beta) and a colleague learned about Pavlov’s work from German journals, corresponded with him, and published a brief article in the Psychological Bulletin describing his method and main findings. They emphasized the usefulness of his research methods but failed to predict the effect the concept of the conditioned reflex would have on American psychology.15

  But in 1916 John B. Watson—whom we are about to meet—began to spell out how Pavlovian conditioning enlarged the behaviorist theory of psychology, and a few years later he termed the conditioned reflex “the keystone of the arch” of behaviorist theory and methodology.16 In

  1927 Pavlov’s book, Conditioned Reflexes, appeared in English, and from then on behaviorist psychologists rapidly absorbed his ideas and borrowed his research methods. The number of articles on Pavlovian conditioning published in psychological and medical journals increased geometrically from the mid-1920s on, totaling nearly a thousand by 1943.17 In 1951, Professor Henry Garrett of Columbia University summed up the impact of Pavlovian ideas on experimental psychology, which had been largely behaviorist for more than three decades:

  There is perhaps no subject in experimental psychology upon which more time and effort have been expended than upon the conditioned reflex. The acquisition of conditioned reflexes by animals, children, and adults; the relative ease of conditioning of various reflexes; the stability of conditioned reflexes, their extinction and reappearance; the relation of school learning to ease of formation of conditioned reflexes… [have all] been subjected to experimental attack… Many psychologists hoped—and the strict objectivists believed—that the conditioned reflex would prove to be the unit or element out of which all habits are built.18

  Mr. Behaviorism: John B. Watson

  No one did more to sell behaviorism to American psychologists than Professor John B. Watson of Johns Hopkins University. A gifted huckster, he energetically and skillfully peddled himself and his ideas to his colleagues, rose swiftly to the top of his profession while launching the behaviorist movement, and later, having been expelled from academia because of a sexual scandal, had a second and financially lucrative career as psychological adviser to a major advertising firm.19

  Like the fictional traveling salesman, Watson exuded self-assurance, stated his views flamboyantly and with certainty, and was a lifelong womanizer. Behind the facade, however, he was insecure, afraid of the dark, and emotionally frozen. He could be sociable and charming in company, but if the conversation turned to deeper feelings he would leave the room and busy himself with chores. He was loving to animals but almost incapable of expressing affection to the people in his life. (He never kissed or held his children; at bedtime he shook hands with them.) After the untimely death of his second wife, whom he seems to have cared for deeply, he never spoke of her to their two sons, one of whom later bitterly recalled, “It was almost as if she had never existed.”20 No wonder he was the champion of a psychology that rejected introspection and self-revelation, dealt only with external acts, and as experimental subjects preferred rats to human beings.

  Watson’s success story was as remarkable as any by Horatio Alger. Born in 1878 near Greenville, South Carolina, he was the son of a petty farmer of violent nature and unsavory reputation, and an upright, devout Baptist woman. Torn between these dissimilar models of adulthood, Watson was a shiftless, indolent small-town boy. When he was thirteen, his father abandoned the family and ran off with another woman, and his mother sold the farm and moved to Greenville. There Watson, teased by classmates for his country ways and upset by his father’s abandonment, did poorly in school. “I was lazy,” he later recalled, “somewhat insubordinate, and, so far as I know, never made above a passing grade.” Like his vanished father, he had a penchant for violence: He often boxed with a friend until one or both were bloody, was much addicted to what he called “nigger fighting” (beating up blacks), and was arrested twice, once for racial brawling and once for firing a gun within city limits.

  Despite his redneck attitudes and habits, he somehow developed the desire to make something of himself and had either the courage or effrontery to request a personal interview with the president of Furman College, a small Baptist institution in Greenville; he was granted the interview and made a good enough impression to be accepted as a student. He had intended to study for the Baptist ministry—his mother’s wish—but, always rebellious, turned against religion. He was never at ease with his fellow students, but when he grew into a strikingly handsome youth with sharp, clean-cut features, a strong chin, and dark wavy hair, he began a lifelong series of affairs. He was serious enough about his ambition, however, to work hard and do well academically, and he particularly liked those philosophy courses which included psychological subjects.

  After graduation, Watson taught in a one-room school for a year, but his favorite philosophy professor, George Moore, who had moved to the University of Chicago, urged him to go there as a graduate student. Again Watson was brash enough to go directly to the top. He wrote a boldly self-promoting letter to William Rainey Harper, president of the university, telling him that he was poor but earnest, and entreating him either to waive tuition or let Watson pay it off later. He also persuaded the president of Furman College to write an extraordinarily strong letter on his behalf. President Harper accepted him—on what financial basis is not clear—and off Watson went. He arrived in Chicago with $50 to his name, completely on his own (his mother had died, his father had never been heard from) but ready for anything.

  At first he majored in philosophy, but soon realized that it was psychology he cared about, and switched. He worked hard at his studies and supported himself by holding several odd jobs: he waited on table at his boarding house, served as a janitor in the psychology department, and took care of rats in an animal laboratory. At one point, overwhelmed by anxiety and sleeplessness, he suffered a breakdown and had to spend a month recuperating in the country. Another man, after such an experience, might have become self-searching and interested in introspective psychology; Watson did his doctoral research in the winter of 1901–1902 on how the level of brain development of young rats was related to their ability to learn mazes and open doors to get food. In part, he was simply falling in with the lates
t trend in psychology (Thorndike had announced his puzzle box findings four years earlier), but in part he was choosing the kind of psychology he found congenial:

  At Chicago, I first began a tentative formulation of my later point of view. I never wanted to use human subjects. I hated to serve as a subject. I didn’t like the stuffy, artificial instructions given to subjects. I always was uncomfortable and acted unnaturally. With animals I was at home. I felt that, in studying them, I was keeping close to biology with my feet on the ground. More and more the thought presented itself: Can’t I find out by watching their behavior everything that the other students are finding out by using O’s? *21

  Watson did such excellent work at Chicago that when he graduated, the department offered him an assistantship in experimental psychology. After only two years he was promoted to instructor, after two more to assistant professor-elect, and a year later, at thirty, was offered the chair of psychology at Johns Hopkins University at what was then (1908) a munificent salary, $3,500.

  His swift rise had been, in part, the consequence of carefully cultivated contacts but, in larger part, of splendid experimental work in animal learning. He taught rats to make their way through a miniature replica of the maze at Hampton Court, Henry VIII’s royal retreat outside London. At first the rats needed as much as half an hour to find their way, but after thirty trials they could race through in ten seconds. By what means had they learned the route? To find out, Watson deprived them of first one sensory cue, then another, to see which one was crucial to maze learning. He blinded some of the trained rats; their performance dropped off but rapidly returned to what it had been before. He washed the maze to remove odor cues, but trained rats did as well as ever. He surgically destroyed the sense of smell of some untrained rats, but they learned the maze as readily as intact rats. Hearing, similarly, proved to play no part in their learning. Watson concluded that kinesthetic cues—muscle sensations—were the key element in the rat’s learning process.22