Our discussion of the development of clinical psychology into the 1960s took us a little ahead of ourselves—we need to turn our attention back a few decades to understand some other important developments.

The schools of psychological thought that had developed by the early twentieth century—structuralism, functionalism, and psychoanalysis—differed substantially from one another. But they shared an important similarity: Each tried to understand the inner workings of the mind by examining conscious perceptions, thoughts, memories, and feelings or by trying to elicit previously unconscious material, all of which were reported by participants in experiments or patients in a clinical setting. In each case it proved difficult to establish with much certainty just what was going on in people’s minds, due to the unreliable nature of the methodology. As the twentieth century unfolded, a new approach developed as psychologists challenged the idea that psychology should focus on mental life at all. This new approach was called behaviourism, which advocated that psychologists restrict themselves to the scientific study of objectively observable behaviour. (See Other Voices: Is Psychology a Science? for a modern discussion of the science of psychology.) Behaviourism represented a dramatic departure from previous schools of thought.

John Broadus Watson (1878–1958) believed that private experience was too idiosyncratic and vague to be an object of scientific inquiry. Science required replicable, objective measurements of phenomena that were accessible to all observers, and the introspective methods used by structuralists and functionalists were far too subjective for that. So instead of describing conscious experiences, Watson proposed that psychologists focus entirely on the study of behaviour—what people do, rather than what people experience—because behaviour can be observed by anyone and it can be measured objectively. Watson thought that a focus on behaviour would put a stop to the endless philosophical debates in which psychologists were currently entangled, and it would encourage psychologists to develop practical applications in such areas as business, medicine, law, and education. The goal of scientific psychology, according to Watson, should be to predict and to control behaviour in ways that benefit society.

Why would someone want to throw the mind out of psychology? This may seem excessive, until you notice that Watson studied the behaviour of animals such as rats and birds. In such studies, inferring a mind is a matter of some debate. Shall we say that dogs have minds, for instance, but leave out pigeons? If we include pigeons, what about worms? Animal behaviour specialists staked out claims in this area. In 1908, Margaret Floy Washburn (1871–1939) published The Animal Mind, in which she reviewed what was then known about perception, learning, and memory in different animal species. She argued that nonhuman animals, much like human beings, have conscious mental experiences (Scarborough & Furumoto, 1987). Watson reacted to this claim with venom. Because we cannot ask pigeons about their private, inner experiences (well, we can ask, but they never tell us), Watson decided that the only way to understand how animals learn and adapt was to focus solely on their behaviour, and he suggested that the study of human beings should proceed on the same basis.

Watson was influenced by the work of Russian physiologist Ivan Pavlov (1849–1936), who carried out pioneering research on the physiology of digestion. In the course of that work, Pavlov noticed something interesting about the dogs he was studying (Fancher, 1979). Not only did the dogs salivate at the sight of food; they also salivated at the sight of the person who fed them. The feeders were not dressed in Purina suits, so why should the mere sight of them trigger a basic digestive response in the dogs? To answer this question, Pavlov developed a procedure in which he sounded a tone every time he fed the dogs, and after a while he observed that the dogs would salivate when they heard the tone alone. In Pavlov’s experiments, the sound of the tone was a stimulus (sensory input from the environment) that influenced the salivation of the dogs, which was a response: an action or physiological change elicited by a stimulus. Watson and other behaviourists made these two notions the building blocks of their theories, which is why behaviourism is sometimes called stimulus–response (S–R) psychology.

Watson applied Pavlov’s techniques to human infants. In a famous and controversial study, Watson and his student Rosalie Rayner taught an infant known as “Little Albert” to have a strong fear of a harmless white rat (and other white furry animals and toys) that he had previously not feared. Why would they do such a thing? You will learn more about this study in the Learning chapter, but the short answer is this: Watson believed that human behaviour is powerfully influenced by the environment, and the experiments with Little Albert provided a chance to demonstrate such influence at the earliest stage of life. Neither Watson nor later behaviourists believed that the environment was the only influence on behaviour (Todd & Morris, 1992), but they did think it was the most important one. Consistent with that view, Watson became romantically involved with someone prominent in his environment: Rosalie Rayner. He refused to end the affair when confronted by colleagues, and the resulting scandal forced Watson to leave his position at Johns Hopkins University. He found work in a New York advertising agency, where he applied behaviourist principles to marketing and advertising (which certainly involves manipulating the environment to influence behaviour!). Watson also wrote popular books that exposed a broad general audience to the behaviourist approach (Watson, 1924, 1928). The result of all these developments—Pavlov’s work in the laboratory, Watson and Rayner’s applications to humans, and Watson’s practical applications to daily life—was that by the 1920s, behaviourism had become a dominant force in scientific psychology.

In 1926 Burrhus Frederick Skinner (1904–1990) finished his undergraduate degree, and could not decide what to do with his life. He aspired to become a writer, and his interest in literature led him indirectly to psychology. Skinner wondered whether a novelist could portray a character without understanding why the character behaved as he or she did, and when he came across Watson’s books, he knew he had the answer. Skinner completed his Ph.D. studies in psychology at Harvard (Wiener, 1996) and began to develop a new kind of behaviourism. In Pavlov’s experiments, the dogs had been passive participants that stood around, listened to tones, and drooled. Skinner recognized that in everyday life, animals do not just stand there—they do something! Animals act on their environments in order to find shelter, food, or mates, and Skinner wondered if he could develop behaviourist principles that would explain how they learned to act in those situations.

Skinner built what he called a conditioning chamber but what the rest of the world would forever call a Skinner box. The box has a lever and a food tray, and a hungry rat could get food delivered to the tray by pressing the lever. Skinner observed that when a rat was put in the box, it would wander around, sniffing and exploring, and would usually press the bar by accident, at which point a food pellet would drop into the tray. After that happened, the rate of bar pressing would increase dramatically and remain high until the rat was no longer hungry. Skinner saw evidence for what he called the principle of reinforcement, which states that the consequences of a behaviour determine whether it will be more or less likely to occur again. The concept of reinforcement became the foundation for Skinner’s new approach to behaviourism (see the Learning chapter), which he formulated in a landmark book, The Behavior of Organisms: An Experimental Analysis (Skinner, 1938).

Skinner set out to use his ideas about reinforcement to help improve the quality of everyday life. He was visiting his daughter’s Grade 4 class when he realized that he might be able to improve classroom instruction by breaking a complicated task into small bits and then using the principle of reinforcement to teach children each bit (Bjork, 1993). He developed automatic devices known as teaching machines that did exactly that (Skinner, 1958). The teaching machine asked a series of increasingly difficult questions that built on the students’ answers to the simpler ones. To learn a complicated mathematics problem, for instance, students would first be asked an easy question about the simplest part of the problem. They would then be told whether the answer was right or wrong, and if a correct response was made, the machine would move on to a more difficult question. Skinner thought that the satisfaction of knowing they were correct would be reinforcing and help students learn.

If Grade 4 students and rats could be successfully trained, then why stop there? In the controversial books, Beyond Freedom and Dignity (1971) and Walden II (1948/1986), Skinner laid out his vision of a utopian society in which behaviour was controlled by the judicious application of the principle of reinforcement (Skinner, 1971). In those books, he put forth the simple but stunning claim that our subjective sense of free will is an illusion and that when we think we are exercising free will, we are actually responding to present and past patterns of reinforcement. We do things in the present that have been rewarding in the past, and our sense of “choosing” to do them is nothing more than an illusion. In this, Skinner echoed the sentiments of philosopher Benedict Spinoza (1632–1677), who several centuries earlier had noted that “men are deceived in thinking themselves free, a belief that consists only in this, that they are conscious of their actions and ignorant of the causes by which they are determined. As to their saying that human actions depend on the will, these are mere words without any corresponding idea” (1677/1982, p. 86).

Skinner argued that his insights could be used to increase human well-being and solve social problems. Not surprisingly, that claim sparked an outcry from critics who believed that Skinner was giving away one of our most cherished attributes—free will—and calling for a repressive society that manipulated people for its own ends. The criticism even extended to TV Guide, which featured an interview with Skinner and called his ideas “the taming of mankind through a system of dog obedience schools for all” (Bjork, 1993, p. 201). Given the nature of Skinner’s ideas, the critics’ attacks were understandable—he had seriously underestimated how much people cherish the idea of free will—but in the sober light of hindsight, they were clearly overblown. Skinner did not want to turn society into a “dog obedience school” or strip people of their personal freedoms. Rather, he argued that an understanding of the principles by which behaviour is generated could be used to increase the social welfare, which is precisely what happens when a government launches advertisements to encourage citizens to eat healthy or quit smoking. The result of all the controversy, however, was that Skinner’s fame reached a level rarely attained by psychologists. A popular magazine that listed the 100 most important people who ever lived ranked Skinner just 39 points below Jesus Christ (Herrnstein, 1977).