Before he invented behaviorism, John B. Watson considered learning one of the most important topics in psychology. Watson conducted excellent empirical research on animal learning. He developed behaviorism in part to promote research and elevate the status of learning in psychology. Watson was much less successful in the adequacy and originality of the mechanisms he proposed to explain learning. By assimilating the method of classical conditioning and adopting Pavlov’s theory of stimulus substitution, Watson linked behaviorism with a new method that could compete with both Titchener’s method of introspection and Freud’s methods of psychoanalysis. Watson’s interest in explaining psychopathology led to the discovery of conditioned emotional responses and a behavioristic explanation for the learning of phobic behavior. Watson established learning as a central topic for basic research and application in American psychology. 

Learning in animals is probably the most important topic in the whole study of behavior (Watson, 1914, p. 45). 

No experimenter has yet set his experimental problems in such a way as to construct from his data a guiding theory of habit formation (Watson, 1925, p. 25). 

In 1930, when he revised Behaviorism for the last time, Watson expressed satisfaction that behaviorism was strongly entrenched as a point of view in American psychology. He took the occasion to repeat a major theme of his career, the contrast between the old psychology of James’s and Titchener’s introspection and what he called the new psychology of behaviorism. From his point of view, Watson had achieved great success in his primary goal of changing the subject matter of psychology from consciousness to behavior. After telling his readers that consciousness was the subject matter of the old psychology, Watson repeated the main point of his manifesto on behaviorism (Watson, 1913a), that “behaviorism, on the contrary, holds that the subject matter of human psychology is the behavior of the human being” (1930, p. 2). 

What historical factors led Watson to propose a change in the subject matter of psychology from consciousness to behavior? Although many factors, both in American culture at large and in American psychology, contributed to the origins of behaviorism (Burnham, 1968; Mills, 1998; O’Donnell, 1985), the challenge of explaining learning was central to the origins and subsequent development of John B. Watson’s behaviorism. By 1930 Watson could also take satisfaction that not only behaviorism, but also the topic of learning, was strongly entrenched in American psychology. 

For Watson, behaviorism represented much more than a change in the subject matter of psychology. Many topics in psychology could be approached objectively. Indeed, in one of the first of a genre of critiques of behaviorism, Titchener (1914, p. 5) pointed out that calls for objective psychology were common in the history of psychology, so “Watson’s behaviorism is neither so revolutionary nor so modern as a reader unversed in history might be led to imagine.” The target of Watson’s behaviorism was all introspectionists, especially Titchener. In order to replace the method of introspection, Watson issued a call for the adoption of new methods in psychology for the study of behavior. A corollary of behaviorism was Watson’s call for the adoption of new methods for the study of Learning. 

Behaviorism elevated the status of learning as a topic of research by psychologists. Behaviorism became Watson’s chosen vehicle for calling attention to research on learning. Watson’s (1925) popular book, Behaviorism, was a showcase for research on learning, especially Watson’s own research on emotional learning in children. For Titchener, the most important topics in psychology were sensation and perception. (See Tweney, 1987, for the details of Titchener’s program of research in experimental psychology.) For Watson, behaviorism was a platform from which he attempted to persuade his colleagues and the public that learning was a more important topic for research than were sensation and perception. 

In contrast with Watson’s success in changing the subject matter of psychology from consciousness to behavior, and as Boakes ( 1994) pointed out, Watson was much less successful as a learning theorist. The quotation from Watson with which this article begins indicates that he eventually recognized that his efforts to develop a behavioristic theory of habit formation were not successful. Watson failed to find a behavioristic substitute for Thorndike’s law of effect. He also failed to develop a heuristic explanation for maze learning. After writing an editorial calling for research in comparative psychology on imitation (Watson, 1904), Watson (1908, p. 172) may have been slightly embarrassed when he reported that with respect to his own research on imitation in monkeys, “I unhesitatingly affirm that there was never the slightest evidence of inferential imitation manifest in the actions of any of these animals.” Thus, imitation represented a failure in Watson’s efforts to advance comparative psychology by investigating learning. Watson (1925) simply adopted Pavlov’s theory of stimulus substitution as an explanation for Pavlovian conditioning. Thus Watson does not rank with Pavlov and Thorndike as a learning theorist. Watson’s major contribution to learning theory was the prediction and discovery that emotional responses could be conditioned (Watson & Rayner, 1920). With the exception of the discovery of conditioned emotional responses, Watson’s enduring achievement for learning was an increase in the status of the topic. By identifying the mechanisms of trial and error learning and maze learning as unsolved problems in experimental psychology, Watson paved the way for the neobehaviorism of Hull, Tolman, and Skinner in the 1930s. 

The topic of learning has been neglected in prior scholarship on Watson (for an exception, see Malone, 1990a). Todd (1994) identified Watson’s extension of the province of learning as one of the topics requiring additional historical analysis. He asked, “Could behaviorism have become an important philosophy without specific empirical principles?” (1994, p. 165). The answer is “yes.” Even with very few wellestablished principles of learning, Watson’s behaviorism achieved its collateral objective of increasing the attention paid to the topic of learning. Therefore, an exploration of the role of learning in John B. Watson’s published papers provides an additional key for placing classic behaviorism in a proper historical context. 

How Watson spotlighted the topic of learning 

Learning is mentioned only obliquely in Watson’s ( 1913a) famous manifesto for behaviorism, “Psychology as the Behaviorist Views It.” The purpose of this paper was to change the subject matter of psychology from consciousness to behavior, so it represented more of an attack on Titchener’s structuralism and the functional psychology Watson had been a part of at Chicago than a vehicle for presenting fresh data on learning. Watson mentioned an eclectic melange of several topics for research that could be approached behavioristically. The list included the study of learning and habit formation, instincts, the comparative study of sensory processes including vision in both animals and humans, and a set of applied problems including psychopathology. In his manifesto of 1913, Watson’s characterization of the areas of basic research in psychology was a lament about what he believed to be experimental psychology’s low status among the natural sciences, which he put as follows: 

I do not wish unduly to criticize psychology. It has failed signally, I believe, during the fifty-odd years of its existence as an experimental discipline to make its place in the world as an undisputed natural science. Psychology, as it is generally thought of, has something esoteric in its methods. ( 1913a, p. 163) 

The key to understanding this quotation is Watson’s use of the word methods. Watson’s goal was to replace the method of introspection with “objective” methods. Consider the topics of sensation and perception, which were an important area of research for Titchener and his students (Tweney, 1987). Watson could have simply called for a behaviorism that represented a return to Fechner’s objective methods of psychophysics, but he did not. In his manifesto, Watson did not single out any particular topic in experimental psychology for special favor. 

After the manifesto for behaviorism, Watson’s next major opportunity to advance the agenda of behaviorism was his book on comparative psychology. He used this book as a platform from which to elevate the status of learning as a topic for research by psychologists. Consider Watson’s comments about learning in his treatise on comparative psychology, Behavior: An Introduction to Comparative Psychology (1914). One might expect that instinct would emerge as a key concept in a textbook on comparative psychology. Watson defined an instinct as a behavior on the part of an animal that did not require learning, and he devoted two chapters in Behavior to a discussion of instincts. (See Dewsbury, 1994, for a portrait of Watson as a comparative psychologist, including his interests in instincts.) However, Watson reserved the most praise in Behavior not for instincts, but for the topic of learning, whose importance he described as follows: 

On account of its bearing upon human training, learning in animals is probably the most important topic in the whole study of behavior. Entirely apart from this connection, this division contains the behaviorist’s most important group of problems, since by means of habit formation he finds the most direct way of controlling animal activity. (1914, p. 45) 

Consider three points in the preceding quotation. First, notice that Watson was not interested in animal learning per se as a topic for scientific exploration, but primarily as the topic related to human learning. Second, because the goal of Watson’s ( 1913a) behaviorism was the prediction and control of behavior Watson found the topic of learning relevant because it provided him with a tool for controlling behavior. Third, Watson described the topic how called learning as habit formalion. Habit formation is no longer used as a synonym for learning. As Malone (1990b) pointed out, Watson borrowed the concept of habit formation from William James (1890/1950). 

Watson ( 1917a) had another opportunity to spotlight learning when he reviewed Holt’s (1915) book on psychoanalysis. Holt was an American psychologist from Harvard who attended Freud’s lectures at Clark University in 1909. After he returned to Harvard he wrote a book on ethics that was influenced by Freud’s idea of wish fulfillment. Holt called his book The Freudian Wish and Its Place in Ethics. The book contained a discussion of the Meynert problem, a hypothetical and philosophical explanation of how a child might learn not to put his or her finger into a candle flame despite the impulse to reach out and touch an attractive object. Holt highlighted the topic of emotional learning in children in his book and pointed out that “fear is a normal and necessary ingredient of the learning process” ( 1915, p. 71 ) . However, Holt did not of fer any data, and his discussion of learned fear in children was philosophical. The significance of Holt’s book was that after listening to Freud, Holt talked about learned fear as a psychological topic worthy of the attention of psychologists. Holt (1915, p. 74) went on to conclude his theoretical discussion of the Meynert problem with the statement that “the mechanism of learning is by no means understood as yet.” 

In a review of Holt’s book, Watson’s response to the challenge of Freudian psychoanalysis was a call for psychologists to turn to research on learning. Watson (1917a, p. 86) believed that psychoanalytic concepts, which he considered mystical entities, could be explained in terms of “well-known principles of habit formation.” Watson followed Holt and discussed the Meynert problem. In the context of understanding the mechanism by which children’s fears were acquired, Watson made another call for elevating the status of the topic of the mechanisms of learning within experimental psychology: 

In these few experiences a genuine learning process is involved and the explanation of this learning process-regardless of whether the act is acquired in few of many trials-is what I consider one of the chief problems in psychology. (1917a, p. 89) 

Watson has transformed his research interest in children’s fears from an old philosophical conundrum, how children learn to keep their hands out of a burning candle, into “one of the chief problems of psychology.” 

Watson was explicit in indicating that behaviorism represented a shift in the importance of the topics psychologists selected for research. For Watson’s behaviorism represented a shift away from sensation and perception toward a focus on learning and habit formation. Watson described the change as a shift from the structural analysis of the unit of sensation toward the units of learning and habit formation. He rejected 

the introspectionist unit concept [of] sensation. The reason for the omission is clear. When a unit changes in a science the problems and points of interest shift . . .The mechanism of habit formation . . must await the working out of just those factors which the behaviorists insist upon. ( 1917a, p. 92). 

Here Watson offered to set the theoretical agenda for successive generations of behavioristic learning theorists. Thus a characteristic of Watson’s rhetoric was to call attention to the importance of learning as a topic for research within experimental psychology. Another illustration of this practice occurs in a paper on maze learning, where Watson wrote, “The control of habit is one of the most vital problems in every system of psychology” (1917b, p. 59). Although Watson was a great salesman for research on the topic of learning, he was less successful as a learning theorist. His first theoretical failure was with maze learning. 

Watson’s failure to explain maze learning behavioristically 

Why did Watson abandon consciousness as an explanatory concept? One good place to start considering this question is by comparing the discussions of Small and Watson on maze learning in the rat. Small (1901 ) constructed a maze for white rats from a diagram of the Hampton Court Maze in the Encyclopedia Britannica. He placed food at the center of the maze and found that his rats rapidly learned to run from the start location, through a complex series of passages, until they reached the food. Looking down on the uncovered maze, Small recorded the errors when a rat entered a cul-de-sac and the amount of time the rat required to find the food. The maze was complicated and Small was impressed by the proficiency with which the rats mastered the task. Watson (1907) duplicated Small’s maze, replicated Small’s experiment, and began an experimental analysis of the factors that influenced maze learning in rats. Watson and Small obtained essentially the same data, but their interpretations of the mechanism of learning and even their choices for presenting the data were profoundly different. Small did not trust the learning curve of Thorndike (1898) as an adequate representation of the process of learning, but Watson proudly filled his paper with beautiful learning curves. Watson found that the average length of time to find the food was 16 min on the first trial and that the time dropped to about 1 min after only 10 trials. For both Small and Watson, the question was, What is the mechanism underlying the process of learning? 

Small’s mechanisms for maze learning: Consciousness and sensations 

In Small’s and Watson’s day, comparative psychologists were sharply divided over anthropomorphism and the law of parsimony. Small was an eclectic theorist who belonged in the camp of those who were willing to attribute components of human consciousness to animals. Unlike Thorndike (1898), he thought animals could reason and he chided the advocates of parsimony as inflexible extremists in very clear language: 

Some modern comparative psychologists’ abhorrence of anthropomorphism leads to the opposite extreme. . . . .Is not a certain amount of chastened anthropomorphism a wholesome specific, a kind of saving grace against scientific pedantry?. . . . The law of parsimony is important no doubt, but it may be employed too rigorously. (Small, 1901, p. 228) 

Small used what would now be called cognitive language to describe the process of maze learning: “The selection of paths begins to be purposive” (Small, 1901, p. 212). In other words, Small anticipated the language of Tolman’s (1932) purposive behaviorism to the extent of using the term purposive. Small never mentioned the construct of Tolman’s (1948) cognitive map, but he did use a similar cognitive concept, imagery, to describe maze learning when he wrote, “There seemed to be some kind of an image in his mind that he was trying to follow . .He apparently knew when he was on the right and when on the wrong road” (Small, 1901, pp. 212-213). Small mentioned consciousness frequently in his discussion. 

Small’s explanation of maze learning also included a second, much more molecular level of analysis. He discussed the various modalities of sensation, including smell, sight, and tactual motor sensations. The tone of this discussion was quite different from the discussion of consciousness. Small believed that the rats acquired a motor memory in learning the maze. This memory included a representation of distance intervals and proper turns. Small concluded his paper with a call for other researchers to consider the possibility of thinking about maze learning in tactual motor terms. Watson answered Small’s call for a sensory analysis of maze learning. 

Watson’s mechanism for maze learning: Kinesthetic sensations only 

Simply put, Watson applied the law of parsimony to Small’s mechanisms by rejecting Small’s discussion at the level of consciousness. In other words, Watson was willing to run what Small called the risk of “scientific pedantry.” Watson (1907, p. 94) rhetorically asked, “Why, then, in the case of the rat, need we assume the presence of motor images?” Watson followed Small by concluding that the rat learned the maze on the basis of kinesthetic sensations. Watson recognized that he arrived at this conclusion by a process of eliminating other sensory candidates. Watson rejected all of Small’s cognitive processes such as imagery as follows: “No one would dream of affirming that such a complexity in the cortical processes as this would call for could exist in the case of the rats” (Watson, 1907, p. 94). Of course, we now know from the work of O’Keefe and Nadel (1978) and other neuroscientists that the hippocampus is the structure in the brain of rats that is involved in maze learning, but this information was not available to Watson. 

Watson discovered that extramaze visual cues were important in maze learning for normal rats. When he rotated the maze by 180 for normal rats, he found that these rats were “absolutely lost” (1907, p. 87). However, this discovery was made rather late in the collection of the data and Watson decided to simply present the data rather than to speculate about a possible interpretation. 

In conclusion, Watson’s research on maze learning was basically empirical. Although Watson rejected interpretations of the data that included consciousness, he left the problem of maze learning without a satisfactory explanation. 

Although the Chicago school of maze learning in rats produced several additional publications (Carr & Watson, 1908; Peterson, 1917) the theoretical interpretation of the results in terms of Watsonian concept remained vague. At the end of an extensive monograph on maze learning, Peterson, who had worked as a graduate student with Watson at Chicago, reluctantly concluded that “the great problem of how learning takes place is yet largely unsolved” (1917, p. 46). Watson sought to impress the readers of Behaviorism (1925) with the learning abilities of rats in the maze by presenting an impressive learning curve for maze learning, but he remained fixated on his theoretical position that habit formation could be reduced to a kinesthetic sensation in which “the muscular stimuli coming from the movements of the muscles themselves are all we need to keep our manual responses occurring in proper sequence” (1925, p. 176). Watson’s school of maze learning came to a dead end before 1920. In Behaviorism, Watson (1925) reprinted the learning curve from his paper of 1907 and then concluded that the mechanism underlying maze learning and other manual habits “have never been worked out in a wholly satisfactory manner” (1907, p. 171). Watson’s legacy was to pass along to the next generation of researchers in animal learning the problems he had been unable to solve. 

Most historians of learning theory would conclude that the problem of maze learning remained unsolved until Tolman (1948) introduced the construct of the cognitive map. After discussing and rejecting the point of view advocated earlier by Watson, Tolman advocated a point of view called field theory that assumed that “in the course of learning [a maze,] something like a field map of the environment gets established in the rat’s brain” (1948, p. 191). Tolman’s (1932) purposive behaviorism represented a return to the kind of theorizing Small had introduced into learning theory at the beginning of the 20th century. However, Small does not appear in Tolman’s writing as the source of purposive behaviorism. Tolman (1932, p. 12) credited McDougall (1926) for the origin of the term purposive behaviorism. After Watson’s failure to explain maze learning, Tolman successfully proposed a cognitive explanation of maze learning that remains viable today. 

Watson’s failure to improve on Thorndike’s law of effect 

Thorndike, with a bit of hubris, called the identification of the mechanism of associative learning, “perhaps the greatest problem of both human and animal psychology” (1898, p. 103). The law of effect was Thorndike’s well-known explanation for the trial-and-error learning in the puzzle box. Thorndike’s interpretation of his data was that satisfaction increased the preceding response and dissatisfaction decreased it. Watson quoted Thorndike’s law of effect in his book on comparative psychology, but he was skeptical of Thorndike’s assumption that “the successful act is pleasant, and the unsuccessful act is unpleasant” (1914, p. 256). Watson believed that Thorndike’s law of effect was dangerously close to venturing into inferences about consciousness in animals. Similarly, Watson’s student Harvey Garr (1914) was skeptical of the law of effect. Carr simply did not believe Thorndike’s assumption that “all eliminated acts are unpleasant and that all surviving acts are pleasant” (1914, p. 164). 

In addition to the maze, Thorndike’s puzzle box provided another preparation for the study of animal learning by behaviorists. Inspired by Thorndike’s ( 1898) puzzle boxes, Watson developed a sawdust box in which sawdust was placed beneath a box with a hole in the floor. Watson placed food in the box and measured the time required for the rat to burrow through the sawdust to obtain the food. 

Watson conducted an experiment on delay of reward that was designed to provide an empirical test of Thorndike’s law of effect. Watson reasoned that if Thorndike were correct, the pleasure from an immediate reward would be greater than the dissatisfaction from a delayed reward. Using his sawdust box and two groups of rats, Watson (1916a) compared the learning curves for a group of rats that received an immediate reward upon entering the box with a second group where the reward was delayed for 30 s. Watson reported that the learning curves for the two groups of rats were almost exactly identical, a somewhat puzzling result. Years later, Grice (1948) discovered that a delay of reward as short as 0.5 s was effective in producing a decrement in the acquisition of the behavior of lever pressing. In Watson’s study, the ef fectiveness of the delay of reward may have been ineffective because the food was visible in the dish during the delay. Watson noted that his rats were very active during the delay, trying to get at the food. Nevertheless, Watson’s (1917b) data led to skepticism among classic behaviorists about the validity of Thorndike’s law of effect. 

Watson never developed a behavioristic alternative to Thorndike’s law of effect. After reviewing research on motor habits in Behaviorism, Watson remained scornful of the idea that pleasure and displeasure were associated with successful and unsuccessful movements during learning. Watson attacked Thorndike as follows: 

Only a few psychologists have been interested in the problem. Most of the psychologists, it is to be regretted, have even failed to see that there is a problem. They believe that habit formation is implanted by kind fairies. For example, Thorndike speaks of pleasure stamping in the successful movement and displeasure stamping out the unsuccessful movements. Most of the psychologists talk quite volubly about the formation of new pathways in the brain, as though there were a group of tiny servants of Vulcan there who run through the nervous system with hammer and chisel digging new trenches and deepening old ones. (1914, p. 166) 

This passage demonstrates that Watson’s rhetoric of attack on Thorndike was relentless, but Watson did not have a behavioristic alternative to Thorndike’s law of effect. Only when Skinner (1938) developed the concept of the operant and the principle of reinforcement did behaviorists have an alternative to Thorndike’s law of effect. 

Watson’s use of James’s concept of habit in preference to learning 

The term learning does not appear in the index of the revised edition of Watson’s (1930) Behaviorism, but habit formation is listed. There were no chapters called “Learning” in any of Watson’s books, but each edition of Behaviorism contained a chapter on habits. Therefore, at least as a title for a chapter, Watson was more comfortable with the concept of habit than he was with the concept of learning. When Watson wrote about habits, he was building on a conceptual framework he inherited from William James. 

Although Watson’s ideas about learning have frequently and correctly been linked with Pavlov, it was James who had the most influence on Watson’s early thinking about learning. In 1937, John Watson wrote an informative letter to Ernest Hilgard in which he described the development of his early thinking about learning. One can infer from Watson’s letter that Hilgard asked Watson about the influence of Pavlov and Bechterew on his early thinking about learning. Watson’s reply was that neither Pavlov nor Bechterew “had much influence in shaping my early convictions” (Letter from Watson to Hilgard, February 18, 1937). On the contrary, Watson wrote, “I had worked the thing out in terms of HABIT formation” (Letter from Watson to Hilgard, February 18, 1937). If neither Bechterew nor Pavlov influenced Watson, that leaves the question of whose ideas about habit first influenced Watson’s thinking about learning. The answer is William James. 

In his autobiography, Watson (1936) wrote that he learned his James as a graduate student at the University of Chicago under James Angell. Angell was strongly influenced by James’s Principles of Psychology ( 1890/ 1950) and Angell received a master’s degree in psychology at Harvard under James. After Watson arrived at Hopkins, James’s concepts influenced the organization of his teaching because “for two years at Hopkins I taught a modified James type of general psychology” (Watson, 1936, pp. 276-277). Thus Watson was very familiar with the conceptual framework and chapter titles James used to organize Principles of Psychology. In his books on behaviorism, Watson was inclined to use the same titles for chapters that James had used. James had chapters on habit, instinct, and emotions, and in Behaviorism Watson also has chapters on habit, instinct, and emotions. 

Watson proposed a simplified and selective adaptation of James’s ideas about learning. Watson was not willing to follow James beyond the mechanism of the reflex arc. For example, James ( 1890/1950) used the concept of contiguity as a mechanism for forming associations, but for Watson there was “no necessity for speaking of `associations”‘ (1914, p. 260). Watson’s classic behaviorism carried with it the implication that “there are no reflective processes (centrally initiated processes)” (1913a, p. 174). Therefore, Watson rejected any mechanism of learning that appeared to involve centrally initiated processes, and this included James’s use of associative mechanisms. The elimination of centrally initiated mechanisms left Watson with very few theoretical processes for explaining learning. His initial list was limited to “terms of stimulus and response, in terms of habit formation, habit integrations and the like” (Watson, 1913a, p. 167). 

James’s use of the reflex as the foundation unit of habit 

James’s theoretical treatment of habit was analytic. He used a metaphor from chemistry in which a habit was compared with a chemical compound similar to plastic and the task of the scientist was to identify the elements from which the habit was constructed, which permitted the behavioral plasticity. What was the unit similar to the element in chemistry from which a complex habit was constructed? James’s answer was that a habit was “nothing but a reflex discharge . .The most complex habits are . . nothing but concatenated discharges in the nervecenters, due to the presence there of systems of reflex paths” ( 1890/ 1950, pp. 107-108). Thus James reached within the nervous system to the concept of the reflex arc, with its sensory and motor paths, for his explanation of how learning occurred. For James, learning a habit at first required conscious attention to whole chain of reflexes. Then with practice the habit became automatic, so that each muscular contraction produced a sensation, which elicited the next muscular contraction, and so on, so that consciousness was no longer required for the performance of well-learned habits. 

Watson’s analysis of motor habits simply followed James, but omitted James’s discussion of consciousness. Thus Watson’s (1914) analysis of how a rat learned to run a maze for food focused on the stimuli and responses involved in the chaining of reflexes. The learning theorist’s task was to specify “(1) the number, location, and serial order of functioning of the reflex arcs until food is reached; and (2) the stimulus which releases each arc” (Watson, 1914, p. 207). 

The publication of Watson’s book on comparative psychology marked the end of the first phase of Watson’s interest in the topic of learning. Although Watson published further occasional papers in comparative psychology, his major research interest underwent a profound switch from animal learning to emotional learning in infants. A major problem in the historiography of Watson’s behaviorism is to account for this shift. 

Why did Watson abandon comparative psychology for emotional learning with infants? 

Watson’s most famous experiment in learning was the discovery of conditioned emotional responses in the laboratory experiment with Little Albert (Watson & Rayner, 1920). This experiment was designed to demonstrate that classical conditioning provided a mechanism for explaining phobic behavior in humans. Furthermore, Rilling (2000) has also interpreted this experiment as a psychoanalytically inspired attempt to capture in the laboratory a simplified analogue of Freud’s concept of displacement, specifically the “transference” of emotion from rat to rabbit in an infant. It represented a switch from basic research in comparative psychology to the application of Pavlovian learning theory to a problem in psychopathology. How is this major transition from basic research with animals to applied research with humans to be explained? 

A clue to Watson’s early thinking about the future direction of his career emerges from a letter he wrote in 1908 to E. B, Titchener at time when his primary commitment was to comparative psychology. Although Watson in 1913 became famous by attacking Titchener’s psychology, Watson and Titchener maintained an intimate and very warm correspondence that began in 1906 while Watson was at the University of Chicago and ended in 1925 with Watson working in advertising at the J. Walter Thompson company in New York City. 

Early in his career and before he developed behaviorism, Watson was a great admirer of the scientific rigor and dedication Titchener brought to experimental psychology. Watson acknowledged his debt to Titchener as follows: “After these two men [Angell and Donaldson] I have always placed your work and what I know of you personally. I am not so sure that I owe you as much as I owe them” (Letter from Watson to Titchener, December 19, 1908). In particular, Watson admired the rigor of Titchener’s textbook on experimental psychology. In addition, Watson indicated that Munsterberg, Jastrow, and Cattell, a set of psychologists who were interested in the application of psychology, “might never have lived so far as influencing my work” (Letter of Watson to Titchener, December 19, 1908). Note that this correspondence took place before Watson wrote his manifesto attacking Titchener’s school of psychology. (See Larson and Sullivan, 1965, for additional details about Watson’s relationship with Titchener and the development of behaviorism.) 

Watson’s correspondence with Titchener also reveals that he was considering abandoning the field of comparative psychology for research on humans as early as 1908. Watson’s lament about low academic salaries provided the context within which his letter to Titchener was written. Evidently Titchener believed that he might receive an offer to leave Cornell for Yale. As a biographical footnote, Watson scholars have been interested in the cause of his stress at the University of Chicago and the reason for his unhappy marriage to Mary Ickes. Watson got married while at the University of Chicago under the illusion that a married man with the additional responsibilities of a family would receive a higher salary than a single man. “I know what it is to be hard run. I ran into debt to the extent of $2300 in order to get my degree. Then thinking that I should be advanced financially faster than I was I got married. Ever since then I have been on pins and needles” (Letter from Watson to Titchener, December 19, 1908). Watson thought of himself as overworked and underpaid. In the same letter, Watson asked for career advice and mentoring from Titchener: 

In the summer if I can come [to Cornell] I want to talk over the field with you. Some people tell me that I am making a mistake in not doing work on the human side. Perhaps I am. But I am sure no one can do good human work and good animal work at the same time. I get discouraged because I can’t. I sometimes think that a reputation won on animal work must be very ephemeral . .I should value a frank statement from you. 

(Letter from Watson to Titchener, December 19, 1908). 

This letter reveals that Watson’s colleagues were urging him to drop comparative psychology in favor of research with human subjects. In this very intimate letter of 1908, Watson told Titchener that his reputation would last longer if it were based on research with humans rather than on research with animals. History has shown that Watson’s self assessment was correct. Thus Watson appears to have turned away from comparative psychology in part to enhance his reputation and the standing of behaviorism in American psychology. 

Behaviorism began simply enough as an objective point of view in comparative psychology that rejected inferences of consciousness and called instead for the study of behavior (Watson, 1909). After the publication of his famous manifesto (1913a), Watson’s strategy for building behaviorism was to extend the method from animals to humans. He knew that his reputation and the standing of behaviorism would be enhanced by an extension of behaviorism to a problem that could be addressed with human subjects. 

Affection and emotion as research topics for behaviorism 

Watson’s strategy was to search for a topic that had been investigated with the methods of introspection and then to propose to study the topic behavioristically. Shortly after the publication of “Psychology as the Behaviorist Views It” ( 1913a), Watson ( 1913b) published a follow-up paper in which he identified imagery and affection as topics that appeared to his colleagues as stumbling blocks to the acceptance of behaviorism. Watson never conducted research on imagery, but affection came to dominate Watson’s research program by 1920. As was often the case with Watson, his initial discussion of a topic was an attack on his colleagues. Titchener and other psychologists used the technique of introspection to investigate the topic of the emotions. Not surprisingly, Watson attacked Titchener’s use of introspection and said, “I have no sympathy with Titchener’s view” (Watson, 1913b p. 426). Watson’s approach to emotion was to describe affection as a sensation that could be investigated peripherally, but he was vague on the methods that could be used to investigate the topic. 

Watson continued to assert that affection was open to experimentation, and for the first time he used Pavlov’s new theoretical concept of stimulus substitution to explain how phallic symbols and fetishes in humans could be explained by this mechanism of Pavlovian conditioning. As Watson put it, “Certainly many objects. . . . do not in the beginning arouse these groups, but through this ordinary mechanism of habit come later to arouse faintly the one or the other (substitution)” (1914, p. 25). This is an early example of a characteristic pattern in Watson’s behaviorism. An interesting phenomenon in human behavior, here phallic symbols and fetishes, is “explained” without any data by invoking a mechanism from animal learning, Pavlov’s theory of stimulus substitution, as an explanation. It took Watson 7 years of hard conceptual and empirical work to make the transition from these few speculative comments about affection and bring the phenomenon into the laboratory with the experiment with Little Albert (Watson & Rayner, 1920). Much of this ef fort involved Watson’s struggle to bring together the conditioned reflex and behaviorism. 

Three phases of Watson’s thinking about the conditioned reflex 

At the conclusion of the excellent historical book on John B. Watson and classic behaviorism, Todd (1994) identified unraveling the role of the conditioned reflex at the various stages of Watson’s thinking about behaviorism as a topic for further historical analysis. This section addresses Todd’s question. 

Today, every student who has taken a course in introductory psychology has been exposed to Pavlov’s idea of the conditioned reflex. In Wat son’s day the conditioned reflex was a new and arcane topic whose literature, for the most part, was buried in obscure Russian journals. Pavlov’s (1927/1960) major book, Conditioned Reflexes, was not translated into English until 1927, long after Watson’s most productive period. Thus Watson faced a formidable cultural barrier in his struggle to assimilate the Russian literature into the culture of American behaviorism. 

With the exception of Pavlov’s ( 1906) Huxley Lecture, very few translations into English of the original Russian papers on classical conditioning were available. American psychologists may have first learned the basic ideas about classical conditioning from an important article by Yerkes and Morgulis (1909) called “The Method of Pawlow in Animal Psychology” that appeared in the Psychological Bulletin. This article provided an overview of the Russian work for an American audience. This article contained the drawing of the dog in the Pavlov harness that has been reproduced in so many texts that it has become one an icon of experimental psychology. Though generally informative, Yerkes and Mogulis’s article was somewhat vague about the procedural details necessary to replicate the Russian work on conditioned reflexes. 

The key word in Yerkes and Morgulis’s paper was method. At first, American psychologists such as Watson were not interested in Pavlovian conditioning as a tool for conducting research on the basic mechanisms of learning. It was a methodological tool that was considered useful for addressing other problems. For example, in his 1914 book on comparative psychology, Watson’s discussion of classical conditioning took place in the context of a description of discrimination learning in a Pavlovian preparation as a tool for comparative research on the sensory capacities of animals. Watson was skeptical about the utility of Pavlov’s method for research on animal psychophysics because he felt that the data from the preparation were not as reliable as the students of Pavlov claimed. 

For purposes of historical clarity, the development of Watson’s thinking about the conditioned reflex is described in three phases. The first phase was an empirical phase in which Watson tried, with very limited success, to replicate the Russian work. The second phase was connecting behaviorism with psychopathology. This phase was the brilliant zenith of Watson’s career and was both a theoretical and an empirical success. The final phase was the role the conditioned reflex played as the unit of learning in Watson’s popular book, Behaviorism (1925). This phase was speculative and notably free of new data. In this final phase of behaviorism, classical conditioning replaced William James’s habit as the unit of learning and Watson appealed to classical conditioning to support his extreme environmentalism. Each of these phases is considered in the sections that follow. 

The empirical phase: The American Psychological Association presidential address and the failure to replicate Pavlov 

As Boakes (1984) and Coleman ( 1988) pointed out, it was Bechterew, not Pavlov, who had the greater initial influence on Watson. When he became interested in classical conditioning, Watson’s strategy was to read the literature and then attempt to replicate the Russian work in his laboratory at Johns Hopkins. In 1914 Watson called the attention of his graduate seminar to the French edition of Bechterew ( 1913) and the class set about translating and discussing the book. Carl Lashley was a student in the seminar and he described the events that led Watson to conduct experiments on classical conditioning as follows: 

In the spring I served as a sort of unpaid assistant and we constructed apparatus and planned experiments together. We simply attempted to repeat Bechterew’s experiments. We worked on withdrawal reflexes, knee jerk, pupil. Watson took the initiative in all this, but he was also trying to photograph the vocal cords, so I did much of the actual experimental work. I devised drainage tubes for the parotid and planned the salivary work which I published. (Letter of Lashley to Hilgard, May 14, 1935) 

In 1915, Watson gave his presidential address to the American Psychological Association (APA) on “The Place of the Conditioned-Reflex in Psychology.” The purpose of this paper was a proposal from Watson for replacing the method of introspection with the method of classical conditioning as a methodological tool for conducting research on humans. Watson was explicit on this point: “Since the publication two years ago of my somewhat impolite papers against current methods in psychology I have felt it incumbent upon me before making further unpleasant remarks to suggest some method which we might begin to use in place of introspection” (1916a, p. 89). Thus the context in which Watson turned to the method of classical conditioning was his goal of extending behaviorism from a narrow point of view in comparative psychology to a broader point of view that was relevant to psychology as a whole. Watson was never particularly interested in the study of the mechanisms of classical conditioning in laboratory animals. An examination of Watson’s published papers (see Todd, Dewsbury, Logue, & Dryden, 1994, for Watson’s bibliography) reveals that he never published an empirical paper on classical conditioning in animals other than the brief mention of research with one dog and seven chickens in his presidential address (Watson 1916a). 

Watson was much more optimistic in print about the applicability of the method of classical conditioning to problems involving humans than was his collaborator, Carl Lashley. In his published remarks about classical conditioning, Watson concluded his presidential address with enthusiasm: “In conclusion I must confess to a bias in favor of this method. Time may show that I have been over-enthusiastic about it” (1916a, p. 105). In fact, careful scrutiny of Watson’s presidential address reveals that the data Watson had to present were very meager. Privately and retrospectively, Lashley’s appraisal of the research was decidedly less optimistic than Watson’s. In contrast with Watson, Lashley described the project as a failure to replicate the Russian work: 

As we worked with the method I think our enthusiasm for it was somewhat dampened. Watson tried to establish conditioned auditory reflexes in the rat and failed. I could not get stable conditioned salivary reflexes. Our whole program was then disrupted by the move to the lab. in Meyer’s clinic. There were no adequate animal quarters there. Watson started work with the infants as the next best material available. (Letter of Lashley to Hilgard, May 13, 1935) 

Watson’s rhetoric about classical conditioning as a methodological tool did not match the poor quality of his data on classical conditioning. Watson’s empirical phase of interest in classical conditioning was basically a failure. Today, thanks to the recent historical research on Pavlov by Todes (1997), it is easy to understand why Watson failed to replicate the Russian work. Pavlov had a two-story building, designed to his specifications. Pavlov had a substantial budget for his laboratory that was five times greater than that of any other Russian physiologist. Pavlov had a labor force of praktikanty, physicians who temporarily worked in Pavlov’s laboratory on doctoral dissertations. In the years between 1891 and 1904, about 100 coworkers passed through Pavlov’s laboratory. At the time that Watson became interested in classical conditioning, Pavlov had one of the best equipped and staffed laboratories in the world for neuroscience research. In contrast, Watson had limited funds and an unpaid research assistant. Even those meager resources were lost when one of America’s best comparative psychologists found himself in 1916 without a laboratory for conducting research with animals. Against this background of failure, Watson turned to the topic of psychopathology and to the idea of conditioning emotional responses in infants. 

Watson’s psychopathology phase: How the conditioned reflex became Watson’s unit of psychopathology 

Behaviorism has often been described by its critics as a narrow approach to psychology. In contrast with his critics, Watson considered behaviorism a framework for expanding the scope of experimental psychology beyond the range of topics of Titchener’s structuralism. An important goal for Watson was expanding the scope of behaviorism to include applied topics, especially psychopathology. In a footnote to his presidential address on the conditioned reflex, Watson hinted toward his future interest in extending behaviorism to psychopathology when he wrote, 

I wish I had time here to develop the view that the concept of the conditioned reflex can be used as an explanatory principle in the psychopathology of hysteria and the various `ticks’ which appear in so-called normal individuals. It seems to me that hysterical motor manifestations may be looked upon as conditioned reflexes. (1916b, p. 95). 

In this passage Watson provides a preview of his strategy for expanding behaviorism into the arena of mental health. An explanatory principle developed in the laboratory with animals is generalized to human behavior without data from human subjects. Pavlovian conditioning was about to become a weapon in Watson’s propaganda war with psychoanalysis. In order to understand why Watson turned to classical conditioning to explain psychopathology, it is necessary to consider how Adolf Meyer and E. B. Titchener reacted to Freud’s visit to Clark University in 1909. 

Adolf Meyer’s unsuccessful search for a unit of psychopathology 

Freud’s visit to Clark University in 1909 was the equivalent of an intellectual earthquake, tremors from which are still reverberating in American psychology. The details of the visit have been ably described by Rosenzweig (1992). Adolf Meyer (1910) and E. B. Titchener (1910) also presented papers at Clark. Adolf Meyer became one of the most important figures in 20th-century psychiatry, and he was Watson’s colleague at Hopkins. Meyer and Titchener shared a skepticism of psychoanalysis that led to correspondence about the definition of American psychology (Leys & Evans, 1990). 

At the meeting, Titchener privately told Meyer that Freud’s psychology was an obsolete psychology of static associationism. Naturally, Titchener considered his psychology of structuralism a valid contemporary theory of psychology and psychoanalysis as an upstart. After he returned to Hopkins, Meyer asked Titchener to provide him with an explanation “as to how you think the problems of Freud and Jung would have to be formulated in order to receive a card of admission to the domains of legitimate enquiry” (Letter of Meyer to Titchener, September 18, 1909, from Leys & Evans, 1990, p. 116). 

Meyer rejected the biological psychiatry of his day, which involved a futile search for a missing lesion of the brain that might cause psychopathology. The rejection of biological causes led Meyer to search for psychological causes of psychopathology and to propose a psychological unit for psychopathology. Meyer chose habit conflicts as his unit of psychopathology. Meyer wanted Titchener to validate his explanation of psychopathology. For Titchener, the sensation was the unit of structuralism. However, Meyer considered this unit too small for applied research on psychopathology. Similarly, Meyer considered research on psychophysics to be divorced from the practical problems faced by psychiatry. Meyer began with the adjustment of an individual to the environment and then considered how life experiences could produce maladjustment. Meyer called his approach psychobiology, and naturally Meyer considered his approach superior to psychoanalysis. Meyer proposed his theory of psychopathology to Titchener as follows: 

Psychopathology needs definite dynamic units in the life of the patients determining the developments. These must be psychobiological. Let us begin with habit conflicts and their influence on the stream of events. (Letter from Meyer to Titchener, September 23, 1909, from Leys & Evans, 1990, p. 135). 

Notice that Meyer simply borrowed James’s idea of the stream of consciousness and his concept of habit, so that a maladaptive habit becomes a habit conflict. 

Titchener called Meyer an amateur psychologist and was not impressed with Meyer foray from psychiatry into psychology. In reply to Meyer, Titchener wrote, “Psychopathology, again, has every right to use its habit-conflicts . .But before habit-conflicts are accepted in psychology, we want to know what they mean” (Letter from Titchener to Meyer, September 25, 1909, from Leys & Evans, 1990, p. 143). In other words, Meyer failed to provide an operational definition of habit conflicts that would assist a psychologist who was interested in using the concept for research on psychopathology. 

Watson adapts Meyer’s formulation from habit conflict to the conditioned reflex 

Watson lived during a cultural period between 1910 and 1920 when the manifesto was a literary form for advancing new ideas in the arts, politics, and science (Heller & Rudnick, 1991). During this period, Watson wrote three manifestos in which he outlined his program for behaviorism. At first behaviorism was simply a point of view in comparative psychology (Watson, 1909). Then behaviorism became a point of view for psychology as a whole (Watson, 1913a). Finally, in this third manifesto, Watson (1916b) generalized behaviorism into the area of psychopathology so that he could compete with concepts from Adolf Meyer’s psychopathology and Freud’s psychoanalysis. The hallmark of Watson’s three manifestos was that they were long on optimistic rhetoric about a program of research based on behaviorism and short on data demonstrating the validity of the approach. 

“Behavior and the Concept of Mental Disease” ( 1916b) is a founding document for the field that has come to be called behavior modification. Watson’s style was first to attack any idea that smacked of mentalism and then to propose a behavioristic conceptual framework as an alternative. Naturally, Watson attacked the physician’s concept of mental disease for the simple reason that Watson rejected the word mental. Watson gave credit to his colleague Adolf Meyer “for describing `mental diseases’ wholly in terms of twisted habits” (1916b, p. 594). However, Watson did not think Meyer had gone far enough. Instead, Watson proposed replacing Meyer’s vague concept of twisted habits with the concept of the conditioned reflex. Watson agreed with Freud that childhood trauma was the cause of psychopathology during adulthood. Watson simply translated Freud’s idea into the language of Pavlovian conditioning, thereby providing experimental psychologists with a familiar conceptual system for approaching psychopathology See Rilling (2000) for additional details of how Watson explained Freud in terms of his behavioristic learning theory Here is Watson’s translation of Freud’s theory into the language of Pavlovian conditioning: 

All such disturbances of habit-superfluous and useless conditioned reflexes-may be found to date back to some primary stimulus (possibly sex trauma, exposure, masturbation, etc., in childhood) which is the conditioning cause operating just as the electric shock given jointly with a visual stimulus operates in forcing the visual stimulus finally to release a group of responses which, until the current was applied, brought none of them. (1916b, p. 593) 

In this passage Watson simply extended the remarks he made in his presidential address to the APA. Watson did not present any data demonstrating that trauma during childhood produced psychopathology during adulthood. He simply accepted the psychoanalytic theory of trauma-induced neurosis. 

To summarize this section, the conditioned reflex became Watson’s unit of psychopathology through the following conceptual evolution. William James began with the concept of habit. Adolf Meyer, building on James, developed the concept of the habit conflict. Watson, building on Meyer and James, turned from the habit conflict to the conditioned reflex. 

The context of Watson’s discovery of conditioned emotional reflexes 

The discovery of conditioned emotional reflexes by Watson and Rayner (1920) was Watson’s most original contribution to learning theory. A conditioned emotional response is the conditioning of an emotion to a previously neutral stimulus after pairing of the neutral stimulus with an unconditioned stimulus that elicits the reflex. For Watson this meant the conditioning of Little Albert’s fear of a rat by associating the touching of the rat with a loud sound that elicited an unconditioned fear response. The context in which the discovery was made involved two steps; the first was theoretical and the second was empirical. Watson introduced this original concept in his paper “Behavior and the Concept of Mental Disease” (1916b). Watson predicted that a new category of conditioned reflex in addition to salivary reflexes and motor reflexes could be produced by pairing any initially nonemotional stimulus with an emotionally exciting stimulus. The prediction was confirmed in Watson’s experiment with Little Albert (Watson & Rayner, 1920) in what has become psychology’s most famous experiment in human classical conditioning (Todd, 1994). Watson’s purpose in the experiment with Little Albert was not primarily as an empirical demonstration of classical conditioning in a human subject, but as a vehicle for demonstrating that phobic behavior could be explained in terms of a mechanism of classical conditioning. By 1920, Watson’s research on problems involving learning was intended to further the application of behaviorism to applied problems, especially psychopathology. 

The final phase: The conditioned reflex becomes Watson’s unit of learning 

In Behaviorism (1925), Watson’s approach to learning relied heavily on explaining examples of human behavior in terms of the mechanism of classical conditioning. His chapter “How to Study Human Behavior” contained an extensive discussion of classical conditioning and Pavlov’s theory of stimulus substitution. The narrative was constructed from a series of anecdotes from human behavior, each of which was then explained in terms of classical conditioning. For example, Pavlov’s theory of stimulus substitution was used to explain how the response of screaming in a 2-year-old child could be substituted for the initial response of fondling and playing with a pet dog. The unconditioned stimulus was that the child was bitten by the dog. The unconditioned response of crying was then produced by the sight of the dog. Watson’s popular style was not to review the literature on classical conditioning, but to propose classical conditioning as a mechanism by which human behavior could be explained in terms of a antecedent stimulus that preceded the response. 

The conditioned reflex as a unit of habit formation 

In Behaviorism, the most creative theoretical advance was the use of the conditioned reflex as the unit from which a whole habit was formed. Watson was challenged for years by the problem of explaining how complex manual habits were formed. Watson was particularly interested in learning during infancy, and he selected for explanation the hypothetical problem of a baby’s reaching for a bottle of milk. In a thought experiment, Watson described how one could nearly perfect the habit by giving the child 10 trials a day for 30 days. For Watson, “the conditioned reflex is the unit out of which the whole habit is formed. In other words, when a complicated habit is completely analyzed, each unit of the habit is a conditioned reflex” (1925, p. 166). Thus, for Watson the conditioned reflex had become the unit of learning. 

Watson described the development of his thinking that led to his identification of the conditioned reflex as the unit of habit as follows: 

Even in 1911 and 1912 when I was publishing my own views, neither [Pavlov nor Bechterew] had helped me much. I had worked the thing out in terms of HABIT formation. It was only later, when I began to dig into the vague word HABIT that I saw the enormous contribution Pavlov had made, and how easily the conditioned response could be looked upon as the unit of what we had all been calling HABIT. I certainly, from that point on gave the master his due credit. (Letter from Watson to Hilgard, February 18, 1937) 

Because it was James who had formulated learning in terms of habits, Watson was describing a transition in his thinking in which ideas borrowed from Pavlov gradually replaced ideas he inherited from James. After Watson, researchers gradually began to write more about the topic of learning and conditioned reflexes as the older discussions of habit were gradually replaced (Malone, 1990a) . By popularizing classical conditioning, in what Coleman (1988) called a Watsonian speculative phase, Watson’s behaviorism helped create the intellectual climate for a subsequent phase of empirical research on the mechanisms of classical conditioning by the next generation of American experimental psychologists. 

Conclusion 

Watson’s contributions to learning are conveniently divided into two major phases: a phase of research and theory in comparative psychology with animals and a phase of research and theory based on the idea of classical conditioning with humans. During the phase of comparative psychology, Watson conducted research on maze learning with rats. Small’s maze and Thorndike’s puzzle boxes were the two preparations for studying what is now called instrumental learning that most stimulated Watson’s early interest in learning. Small was an eclectic theorist whose explanation for maze learning included both consciousness and sensory mechanisms. Watson applied the law of parsimony to Small’s work, thereby eliminating consciousness from his vision of learning but retaining an unmeasured concept of kinesthetic sensations as the explanation of maze learning. Inspired by Thorndike’s puzzle boxes, Watson developed a sawdust box in which a rat had to burrow through sawdust in order to obtain food that was located in a box above the pile of sawdust. Although Watson rejected Thorndike’s law of effect, he acknowledged that he did not have a superior behavioristic explanation for trial-and-error learning. 

When Watson developed behaviorism in 1913, his research program in comparative psychology was running out of steam. He was unable to continue his research in comparative psychology because he lost his space for animal work in the Department of Psychology at John Hopkins. Watson turned to human subjects, in part because he correctly recognized that a reputation based on research and application with human subjects would earn him a more enduring reputation in the history of psychology than a reputation won primarily on animal work in comparative. psychology. Desperate to identify new methods for studying behavior with human subjects that could compete with the dynamic concepts of psychoanalysis and with Titchener’s use of introspection, Watson turned to classical conditioning for methodological and theoretical salvation. Watson identified emotional learning in infants as a problem worthy of the application of the new method of Pavlovian conditioning. 

Watson’s interest in classical conditioning is conveniently divided into three phases. The first phase was an empirical collaboration with Carl Lashley in which these researchers failed to replicate the Russian work in their laboratory at Johns Hopkins. The second phase, the zenith of Watson’s career in learning, predicted and then confirmed in the experiment with Little Albert the existence of conditioned emotional responses (Watson & Rayner, 1920). This work represented the behavioristic application of well-established principles of classical conditioning to a new area, psychopathology. After his exile from academic life, Watson proposed the conditioned reflex as the unit of habit, thereby replacing William James’s vague formulation with a new framework that encouraged the possibility of experimental analysis. After Watson, habit was abandoned as a theoretical concept and was replaced by the concept of learning. 

Watson’s ideas about the mechanisms of learning were not competitive with Pavlov’s or Thorndike’s. Watson identified the explanation of what is now called instrumental learning as an unsolved problem. The neobehaviorists Skinner and Tolman were able to propose explanations for maze learning and operant behavior, respectively, that succeeded where Watson had failed. Throughout the origins and development of his classic behaviorism, Watson remained true to his vision of the primacy of the topic of learning within American psychology.