Chapter 22

John B. Watson and Behaviorism


            During the first decade of this century a number of events occurred which changed the attitude of many psychologists concerning the way psychology had been done since its establishment as an independent, experimental discipline.  One was the controversy over imageless thought between Oswald Külpe and E. B. Titchener.  Some psychologists came to the belief that if two of the finest experimental laboratories in the world could not determine whether or not there were images in the thought processes by means of introspective analysis, then perhaps there was something wrong with the method of introspection.  There was doubt, even in the minds of psychologists who used introspective methods whether it was the sole or even the primary means of obtaining psychological data.

            A second influence came about with the rise of applied psychology.  As we saw in the previous chapter, one of the things that much of applied psychology and particularly the testing movement demonstrated was that behavior had a great deal of utility in applied settings.  By 1913, while most psychologists would have identified with one or the other of the orthodox psychologies of mind, the commitment was not as deep as it had been a decade before.  As early as 1911, even at the meeting of Titchener's own Experimentalists society, Raymond Dodge, then at Wesleyan but later at Yale, challenged Titchener on introspection[1]  That same year, one of Titchener's early graduates, Walter B. Pillsbury, published an introductory textbook in which he defined psychology as "the science of human behavior."  It should be noted that neither Dodge nor Pillsbury rejected introspection as a legitimate method.  They did question, however, its status as the primary source of psychological data.[2]  Not everyone would be so moderate.


Watson's Behaviorist Manifesto


            In 1913 an article appeared proposing a new psychology.  Written by John Broadus Watson, then only thirty-five years old, it opened as follows:


Psychology as the behaviorist views it is a purely objective experimental branch of natural science.  Its theoretical goal is the prediction and control of behavior. Introspection forms no essential part of its methods, nor is the scientific value of its data dependent upon the readiness with which they lend themselves to interpretation in terms of consciousness.[3]


            It was more than a declaration of independence; it was a manifesto against orthodox psychology, stating the intention of behaviorism to occupy the entire field of psychology to the exclusion of introspective psychology.  It was not enough that the study of behavior (contentual objectivity) be lifted to status equal with that of consciousness (contentual subjectivity).  Behavior, in Watson's view, was thereafter to be the only concern of psychology, and its study was to be the definition of psychology.  In Watson's view, psychology had failed in its fifty years as an experimental study to establish itself as a science.  To reach its rightful place, he thought, it must discard consciousness and the study of mental states.[4]

            Watson sought to exclude from psychology all references to the orthodox modes of experience -- mind, consciousness, images, feelings-- anything that could not be demonstrated behaviorally, that is, by the actions of muscles or glands.  Much of Watson's work involved attempts at the replacement of the orthodox subject-matter of introspective psychology with behavioral equivalents:  subvocal speech for thought, discrimination for sensory judgment, and changes in the sex organs for feelings, just to name a few.

            Watson held that the introspective method was notoriously unreliable--as exemplified in the imageless thought controversy.  As Watson saw it, almost all psychology before him was tarred with the same mentalistic brush and was therefore unscientific.  He specified that his quarrel was not only with the structural psychology of Titchener but also with functional psychology, since it also used mentalistic terms and emphases.  He was willing to agree that the functionalist emphasis on biological significance was laudable, but he felt functionalism still failed to be scientific.  In Watson's view, functionalism had slipped into an interactionistic position in which they saw mental states as playing some part in the adjustment of the individual.  This is nothing more than a relic of philosophy, Watson argued, and the whole issue should and can be ignored by focusing on behavior to the exclusion of all else.  He claimed that behaviorism was the only consistent functionalism.  The study of functional capacities expressed in behavior is relatively easily and directly determined; references to conscious states in functional terms are not only uncertain, but also trivial and unreal.  Watson's behavioral "functionalism" lacked the foundation stone of Dewey and Angell's functionalism, however, holism.  Watson was as elementistic as Wundt or Titchener.

            One may assume, Watson said, the presence or absence of consciousness as one wishes; it does not affect the problems of behavior one iota.[5]  A man has something that may be called consciousness--a psychologist, as a human being, has this something.  But so, too, does a physicist, as a human being.  But what the psychologist shares with the physicist in this regard is no more part of his field of research than it is that of the physicist.

            In his "Psychologist as the Behaviorist Views It" and his second article "Image and Affection in Behavior," Watson laid out his plan for a behavioral psychology.  He recognized no demarcation between humans and the "lower animals."  The subject-matter of behaviorism  was the study of how man and animals alike adjust to their environment.  This adjustment was carried out "by means of hereditary and habit...."  The descriptive categories were stimulus and response.  Watson believed that "In a system of psychology completely worked out, given the stimuli the response can be predicted...."  His ultimate goal was "to learn general and particular methods by which I may control behavior.

            Watson saw the utility of the study of behavior.  He believed that "If psychology would follow the plan I suggest, the

educator, the physician, the jurist and the business man could utilize our data in a practical way....[6]

            Watson's views did not excite a sudden change in psychology.  As Franz Samelson has discovered, there was little positive reaction and some negative reaction to Watson's initial statements.[7]  His position was far more extreme than most psychologists, even those who were critical with the reliability and applicability of introspection. 

            One notable negative response came from E. B. Titchener.  In 1914, in a talk before the American Philosophical Society Titchener evaluated Watson's manifesto.  The talk was published as "On 'Psychology as the Behaviorist Views It.'"[8]  Titchener attacked Watson on several levels.  First, Titchener accused Watson of using not the scientific meaning of "mind" or "consciousness" but the everyday usage of the term.  Thus Titchener concluded that Watson's movement was based on a fundamental misunderstanding of what the science of mind is all about.  Titchener also denied Watson's charge that the only lively developments in recent psychology had been in those areas that depended least on introspection such as "experimental pedagogy, the psychology of drugs, the psychology of advertising, legal psychology, the psychology of tests, and psychopathology."  In response to Watson's position, Titchener demonstrated that the foundation and development of these movements were not due to behaviorism but to orthodox psychology, that William Stern's work on legal psychology; Alfred Binet's work on tests, just to name two, were direct outgrowths of these individuals' work in introspective psychology.  "I am not here depreciating behaviorism;" Titchener says, "but I think there is no justification for behaviorism's depreciation of psychology."

            Titchener held that Watson's behaviorism could not replace introspective psychology because the subject-matter of behaviorism was fundamentally different from that of introspective psychology.  It was therefore, in Titchener's terms "logically irrelevant" to introspective psychology.  More seriously, Titchener attacked behaviorism's status as a science.  Because Watson stated that the goal of behaviorism was the prediction and control of behavior, Titchener concluded that behaviorism was not a science at all but a technological enterprise, seeking utility rather than the understanding that is the foundation of a science.

            Watson's enterprise, in Titchener's view, was not psychology at all but a form of biology.  In fact, many biologists had been doing for years what Watson was now proposing to do in the name of behaviorism.  Watson would have psychology give up its independent status as the "science of mind" for a lesser status as part of biology.  Watson, in Titchener's view, was casting away as irrelevant the very aspect that made psychology a discipline -- consciousness.

            In 1913 Watson stood almost alone in his behavioristic convictions, but by the time he issued his last major publication on behaviorism, seventeen years later,[9] his view had swept through psychology in the United States leaving it, in many respects, a new field.


Pavlov and Russian Physiology


            Titchener was correct when he said that Watson's behavioral emphasis was not new.  One generation earlier there had been the work of two Russian physiologists, Ivan P. Pavlov and Vladimir M. Bekhterev.  In turn, it was a publication by Ivan M. Sechenov, the Reflexes of the Brain,[10] which Pavlov acknowledged as the single most important theoretical inspiration for his work on conditioning.[11]




            It is generally agreed that Ivan M. Sechenov (1829-1905) founded Russian physiology.[12]  After early training in Russia and study abroad with Claude Bernard, DuBois-Reymond, Johannes Müller, and Hermann von Helmholtz, he returned to teach physiology at the St. Petersburg Military Medical Academy and at various other institutions; he spent his last years as professor of physiology at Moscow University.

            Early in Sechenov's career, he carried on experimental investigations of the inhibition of reflex movements by the cerebral cortex.  This inspired him to show that there was a physiological basis for psychical processes.  Thereafter, he labored with the problem of demonstrating that the psyche, rather than being independent of the body, is a function of the brain and central nervous system and is therefore a physiological problem.

            His thesis was that psychical activity can be explained by reflex activity.  With his physiological orientation he tended to emphasize the receptor and motor (muscular) phases of the reflex psychical processes.  All physical processes are expressed in motor activity of one sort or another.  A few of his characteristic teachings may be mentioned.  Sechenov identified reflexes as innate or learned.  Learning itself is a process of association.  He implies that contiguity is the most important principle in association, but that learning is not the primary subject of his investigation.  Thinking, Sechenov held, was an inhibited reflex.  In thinking there is the receptive phase of the reflex, and its transmission; but the end of the reflex, expressed in movement, is absent.  In all of this, as Pavlov remarked, Sechenov was developing a theoretical outline.[13]  It was Pavlov who took the giant step of submitting his contentions to experimental study.




            Ivan Petrovich Pavlov, the son of a village priest, was born in Russia in 1849, and received his early education in a local seminary.[14]  In 1870 he entered the natural history section of the University of St. Petersburg specializing in  physiology.  After obtaining his degree in 1875, he enrolled as an advanced student in the medical school, not with any thought of a career as a practicing physician, but as further preparation for a research post in physiology.  His academic success was such that on completion of his thesis, he won a scholarship to Germany, where he worked with prominent physiologists for two years.  Nevertheless, it was not until 1890 that he was made professor pharmacology (later physiology) at the St. Petersburg Military Medical Academy and head of the physiology department of the Institute of Experimental Medicine.  For many years he devoted his research to the processes of digestion.  In fact, half of his career was taken up with work on digestion, for which he received the Nobel Prize in 1904.  Only after the age of fifty did he study what became known as conditioning.  This study covered a span of another thirty years.

            The specific impetus for the study of conditioning was a phase of his work on the digestive glands.  Using the dog as the experimental animal, Pavlov's general method was a surgical arrangement so that digestive secretions flowed to the surface of the body for collection and measurement.  One aspect of his work was the functioning of saliva in digestion.  By operation, a salivary duct could be diverted so that the saliva stimulated by meat in the mouth of the dog flowed through a fistula to the outside of the body where it was collected.  Prior to 1900, and before working with the conditioned response, he had noticed that a dog secreted saliva before the meat was given him.  Further observation showed that this occurred not only when the dog saw the meat, but also when it heard the footsteps of the attendant.

            The secretory reflex with the innate response of salivation to food on the tongue had now become "conditioned" to the sight of the food or the sound of the footsteps of the attendant.  Pavlov realized that this happened because this sight or sound had been so often associated with the ingestion of food.  This is association by frequency of contiguity, as it would be called in associationistic terms.  The term "conditioned reflex" was first applied to this phenomenon in 1901.[15]

            Pavlov wondered whether he should follow up this new lead into an area that many physiologists would view with disdain, since it was "psychic" in nature.  Some leading physiologists, in point of fact, on hearing of his dilemma, advised him against embarking on the work.  On the other hand, he had the example of Sechenov before him.  After a long struggle with himself, he resolved to go ahead and make it a physiological problem by maintaining the role of the external observer with no consideration of introspective findings.[16]  This was in 1900 or 1901.

            He absorbed himself in his new task.  The basic procedures, with the exception of the selection of the stimulus to bring on salivary flow, had already been standardized through his work on digestion.  His already extensive laboratory resources were directed to this new problem.  When the Soviet government came to power his research faculties were expanded.  An increasing number of associates and assistants joined him.  Over the years, some two hundred collaborators worked with him on problems in conditioning.[17]

            The basic model for Pavlov's work was the presentation of two kinds of stimuli:  one that was "appropriate," "biologically adequate," or "unconditioned;" another that was "psychic," "conditioned," or "learned,"[18]  Each reflex has an appropriate (unconditioned) stimulus that brings it on.  If food is placed on the tongue, saliva flows; if the finger is pricked, it is jerked back.  In his studies, Pavlov tended to depend on the food power leading to the salivary response, though other forms were also used.  When a response such as salivation becomes attached to a stimulus that formerly did not arouse it, it is said to be conditioned.

            Practically any stimulus, Pavlov found, can act as a conditioning stimulus to produce a conditioned response.  The salivation to the sight of the food or the sound of the footsteps of the attendant are stimuli for conditioned responses.  Sight of food or the sound of footsteps had come to serve as signals, and they now brought about a response formerly elicited by food in contact with the tongue.

            Pavlov originally referred to "psychic reflexes," that is, reflexes aroused not by the adequate stimulus of meat in contact with the tongue but by some other form of stimulation that had been presented along with the meat.  He almost immediately dropped this term in favor of "conditioned responses".  Over the years, Pavlov preferred to use as conditioned stimuli the sound of a tuning fork, a bell, and a light flash.  These were the stimuli that acquired a new reaction, namely a flow of saliva.

            It should be remembered that, like Sechenov, Pavlov saw this work as a problem in physiology, not psychology.  Pavlov believed that psychology could never be an independent science and that its position was "completely hopeless."[19]  He believed he had completely excluded it from his own work.[20]  Still, Pavlov is honored for his insights into a line of research that significantly affected the direction psychology was to take, particularly in America.    He died in 1936.




            Something must also be said about the physiologist, V. M. Bekhterev (1857-1927), a countryman, a contemporary, and a rival of Pavlov in the opening years of the century.[21]  Independently of Pavlov, he also became interested in the study of conditioning.  He, too, worked at the St. Petersburg Military Medical Academy, from which he was graduated.  After studying abroad, and after holding a chair in psychiatry at the University of Kazan, he returned to a chair in mental and nervous disorders at the Military Medical Academy, where he later had his own research institute.  Bekhterev studied conditioning or as he called it, associative reflexes, through the study of muscular or motor responses.

            By motor responses, Bekhterev meant such processes as retracting the finger from an electric shock.  The associative reflexes were not the result of any mental process, but they remained reflexes.  He became convinced that more complex behaviors could be explained in a similar manner.  Habits were seen as the compounding of motor reflexes, and even the thought processes were essentially activities of the speech musculature.

            He expressed his convictions in a book, Objective Psychology, which appeared in Russian in 1907, was translated into German and French in 1913, and into English in 1932, under the title, General Principles of Human Reflexology.[22]  The change of title reflected the shift to his later preferred Reflexology.  It was a plea for a psychology based upon the tools and concepts of physiology with no appeal to subjective processes  Psychology expressed in a study of states of consciousness was simply ignored.  Objective study would be sufficient for a complete account of man's behavior.


American Comparative Psychology 


            Another of the sources of behaviorism was animal psychology as studied in the United States.  There were also currents in psychology in the United States contemporaneous with Watson that had influenced him, despite his expressed opposition to the views.  This was the case with the approaches of Edward L. Thorndike and Jacques Loeb.




            Edward Lee Thorndike has already been mentioned in Chapter 17 as a student of James and as one of the psychologists at Columbia University with Cattell.[23]  While at Harvard, he had started research with chickens and, lacking more suitable quarters, took advantage of James's generosity and used the basement of his home as a laboratory.  When offered a fellowship at Columbia by Cattell, he took it and continued his work with chickens, "the most educated" pair accompanying him in a basket from Cambridge to New York.

            Along with two psychologists at Clark University, Thorndike deserves credit for introducing the modern laboratory type of experiment into animal psychology.  Pavlov himself acknowledged that the researches in 1898 of E. L. Thorndike were the first experiments in this general research area, but he added that when he began his own work he was unfamiliar with them.[24]

            Thorndike's study of the behavior of kittens in a puzzle box is classic.[25]  A series of these boxes, open-slatted affairs, had each a different "combination" that, when learned, allowed the hungry kitten to escape from the box and to secure food placed outside it.  The learning tasks for a kitten involved strings to pull, buttons to turn, and levers to press.  At first, the kitten's behavior showed excessive activity, clawing all over the box and trying to squeeze through the bars.  In this struggle the kitten happened to claw the string or button, and the door opened.  In other words, the kitten carried on very actively and randomly until the successful act was hit upon.  On repeated trials, gradually, the erroneous, unsuccessful acts were dropped, one by one.  Ultimately, when the kitten was placed in the puzzle box, he would immediately claw the appropriate button or string and escape from the box.

            This process of learning Thorndike came to call trial and error learning.  As the trials succeeded one another, both the number of errors and the time taken to escape decreased.  The learning, as expressed in decrease of errors and time, was gradual.  He interpreted the results to mean that practice stamps in correct responses and stamps out incorrect ones.

            As a result of his studies, Thorndike formulated two fundamental laws of learning:  1) the law of effect, in which it is stated that any act in a given situation producing satisfaction becomes associated with that situation, so that when the situation recurs, that act is also more likely to recur, and 2) the law of exercise in two complementary parts, the laws of use and of disuse.[26]  The law of use says that there is a strengthening of connections with practice; the law of disuse, that there is a weakening of connections when practice is discontinued.  Research he conducted[27] many years later convinced Thorndike that sheer repetition was unimportant and that reward was much more effective than punishment.  The law of exercise is a direct descendant of the old law of association, not the association of ideas, to be sure, but rather a connection between stimulus and response.  In fact, Thorndike would later call his psychological position, connectionism.  The law of effect is of more dubious parentage, but it is at least partially related to the pleasure-pain or hedonistic principle.  Here again, is an objective approach in that functioning has been inferred from behavior.  Thorndike did not hold that psychology could dispense with consciousness, but he did hope that much of psychology could be objectified.  In some ways, Thorndike's influence on modern behavioral psychology is at least as great as that of its touted founder, John B. Watson.  To the degree that behavioral methodology is the significant factor that made behaviorism a viable movement, Thorndike deserves at least equal credit with Watson.

            Thorndike was not alone in the United States in performing pioneer contentually objective research studies with animals, however.  Robert M. Yerkes (1876-1956), under Thorndike's influence, went down the phylogenetic scale to study learning and intelligence in the turtle using a maze .[28]  A Clark University student, Willard S. Small (1870-1943), studied learning using rats and a miniature of the Hampton Court maze and firmly established both the maze as a method and the rat as an experimental animal.[29]




            Jacques Loeb (1859-1924), a physiologist and one of Watson's teachers, must have had some influence on him, although Watson makes little mention of him (and that disparaging), presumably because of Loeb's failure to reject completely an appeal to the psychic processes.  Loeb had revolted against anthropomorphism and sentimentality in interpreting animal activity, but he did not reject consciousness, which he thought to be associative memory or the capacity of the animal learn from experience.[30]  Loeb had announced his theory of tropisms in 1890 and thereafter embarked on mechanistically oriented studies of simple organisms and plants.  The classical or narrower theory of tropism conceives of animal behavior as nothing more than a forced movement of a physical-chemical nature.  In more general fashion, the theory of tropism has to do with the orientation of the organism in a field of force.  According to this view, recourse to such terms as sensation or pleasure is not necessary.


Influence of Functionalism


            Though Watson rejected functionalism as a school, he was at the University of Chicago during its formative years; its emphasis upon activity became part of his heritage.  From his point of view he had just as much a quarrel with functionalism as with structuralism.  From the present perspective his disagreement with the functionalist was on the grounds that they insisted mental processes were an integral part of psychology.  From his point of view they wished merely to study the biological significance of conscious processes rather than to analyze conscious states as did the structuralists,[31] and he found the distinction "unintelligible."[32]  In this connection, a case can be made that a good bit of functionalism's conservatism was no more than lip service to the old tradition of psychology as the science of the mind.[33]  Much as Watson claimed to reject functionalism, his views shared a fundamental similarity with it; he too stressed function and demanded a larger scope of application for psychology.  He differed, unpardonably to James Rowland Angell, in that he sought to analyze behavior into its simplest forms, and thus rejected the wholistic notion that was the primary basis of Chicago functionalism.

            During these years there were also other general trends toward contentual objectivity with which Watson was presumably familiar.  For example, Cattell in 1904 was so far removed from introspection that he claimed most of the research done in his laboratory "is nearly as independent of introspection as work in physics or in zoology."[34]  Cattell cited studies in which no introspective report was asked; for example studies of reaction time, accuracy of perception, color preference, fatigue, animal and child behavior studies.  At about the same time, certain psychologists were even defining psychology as the study of behavior; witness McDougall in 1905[35] and again in 1923[36] and Pillsbury, as we have already seen, in 1911.  Neither one, however, would exclude introspective data from the field of psychology.   This was the step taken most effectively by John B. Watson. 

            Others, working in the same climate of opinion but independently of Watson, also presented general behavioristic statements, excluding mind and consciousness from psychology.  In France, for example, there was  Henri Piéron (1881-1964), who had worked both with Pierre Janet and Alfred Binet, and who declared as early as 1907 that psychology could only be a science of behavior.[37] 


John B. Watson

            Watson carried out one of the most startling scientific coups in American history although his behavioral revolution did not come all at once.


Early Life


            John Broadus Watson was born in 1878 on a farm near Greenville, South Carolina.[38]  There he attended Furman University taking an old-fashioned classical curriculum.  The only science Watson took was chemistry.  There he remained through 1900, leaving with a master's degree.

            Being more interested in philosophy than in psychology, and knowing of the fame of John Dewey, Watson enrolled as a graduate student at the University of Chicago.  He found Dewey "incomprehensible" and almost immediately lost enthusiasm for philosophy.  He continued to minor in the subject however, and took a considerable number of philosophy courses; but, as he himself commented, philosophy somehow did not take hold.  In these years the department of philosophy included the courses in psychology and it was James R. Angell, the functionalist, who awakened his interest in psychology as a career.  A second minor, one in neurology, eventuated from his work in the neurological laboratory of H. H. Donaldson, where he made the acquaintance of the white rat.  He also took biology and physiology under Jacques Loeb, who wanted Watson to do his dissertation with him.  Angell and Donaldson did not consider Loeb quite "safe," so he worked with the two of them instead.  His doctoral dissertation used both neurological and behavioral techniques in the study of the correlation of the behavior and the growth of medullation in the central nervous system of the white rat.  It was to Angell and Donaldson that he dedicated his first book.  In his opinion, these two and Loeb were his most influential teachers.

            He graduated in 1903 and was offered an assistantship to work with Angell.  This he did for a year and then was made an instructor.  With his new position he was able to marry Mary Ickes, a Chicago socialite.

            While he taught the usual kind of Jamesian psychology in the classroom at Chicago, his major interest was in the studies he was conducting in the animal laboratory he had constructed in the basement.  Familiarity with C. Lloyd Morgan's work first stimulated his researches in animal psychology; so also, and even more directly, did the work of Thorndike.[39]  At this time he was not aware of the work of either Pavlov or Bekhterev.  Watson was a hard worker and produced a considerable number of studies with the white rat, the monkey, and the tern before he left Chicago in 1908 for Johns Hopkins.

            At Johns Hopkins he received a full professorship in experimental and comparative psychology and the directorship of the laboratory.  During the period between 1908 and 1920, while at Johns Hopkins University, Watson did his most important work. 

            In 1913, he published his landmark article, "Psychology as the Behaviorist Views it."  Behaviorism did not come to Watson suddenly.  Actually, Watson said, it was in 1904 that he first broached a behavioristic psychology, presumably in conversation with a colleague at the University of Chicago.[40]  He goes on to say that he was told it might work with animals, but not with humans.  Public expression of his views first occurred in 1908 at a colloquium at Yale University.  Four years later, at Columbia at the invitation of Cattell, Watson gave a series of lectures that included the contents of the crucial article.

            In 1914, in his book, Behavior:  An Introduction to Comparative Psychology, he marshalled the available evidence to demonstrate the right of animal psychology to be considered a major specialty.[41]  This was an important consideration for Watson.  Indeed, he admitted in his earliest statement of behaviorism that part of his motivation for a new psychology was embarrassment about the skepticism he met concerning the value and relevance of animal research to psychology.[42]  Animal research contributed very little of value to psychology as long as the latter was considered a study of human experience.  What Watson wished to combat was the kind of purist psychology of human experience epitomized by Titchener and his followers.  In allowing for an animal psychology, Titchener had to appeal somewhat lamely to the method of analogy.[43]  Since an animal shows movements similar to those of a man in similar circumstances, it is possible to reconstruct the animal's consciousness as essentially similar to that of man under these same circumstances.  The observations are then cautiously to be interpreted in terms of human consciousness.  This was also the same sort of procedure used by Angell at Chicago.  While Angell allowed students to do behavioral research, he always wanted analog "introspections" of their presumed conscious processes.  The attention actually paid in Angell's laboratory to this translation into mentalistic terms was not necessarily more than perfunctory, but it was done.  Even Watson's first publication bore the subtitle, "the psychical development of the white rat."  He began to object strenuously to this attitude.  Watson went so far as to call interpreting animal behavior in terms of the information it gives about conscious states, "absurd."[44]


Conditioning in Watson's Behaviorism


            The manifesto of 1913 lacked a major positive characteristic of Watsonian behaviorism--emphasis on the conditioned response as the methodological tool par excellence.  Watson had found the German and French translations of Bekhterev and was familiar with the salivary conditioned response studies of Pavlov, but at the time he was writing his article, he was thinking primarily in terms of English associationist principles, not conditioning.  However, once he came upon Bekhterev and Pavlov, he immediately assimilated their paradigm into his approach. Watson used the conditioned reflex (with particular emphasis on the value of Bekhterev's motor reflex) as the topic of his presidential address before the American Psychological Association in 1915.[45] 

            In 1918, through the facilities of the Phipps Clinic in Baltimore, Watson extended his researches to young children.  Very little experimental work on human infants had been conducted prior to that of Watson and his co-workers.  Baby biographies had been maintained, questionnaires used, and tests developed, but the deliberate manipulative introduction of forms of stimulation demanded by experimental study had hardly been attempted.

            Setting aside conditioning for later discussion, Watson's methods of studying hand preference merit mention as illustrative of the other research techniques he used.[46]  It is well known that the great majority of adults are right handed.  Whether or not this is an instinctive response is the question Watson set out to answer, applying to young infants a variety of ingenious techniques.  He measured the anatomical structure of the arm; the time that the infant would hang suspended from a bar by right and by left hand; and the total amount of work done with each hand by an infant.  The latter was measured by attaching "work adders" (wheels that turn in one direction when there is movement) to both hands; when the child slashed about with his hands the wheel revolved, pulling up the cord to which a small weight was attached.  After reaching toward an object was established in the infant's behavior repertoire, Watson noted the particular hand extended to secure a peppermint stick.  The overall evidence tended to show little or no favoring of the right hand over the left hand.  He therefore concluded the right-handedness was not instinctive but a matter of social pressure--a form of conditioning.

            Watson's book, Psychology from the Standpoint of a Behaviorist, appeared in 1919, was revised in 1924, and revised again in 1929.[47]  It was essentially an attempt to extend the methods and principles of animal psychology into the human sphere.  The value of conditioning as a method of study was extolled.


Later Life


            In 1920, Watson's academic career came to an abrupt end.  Divorce proceedings had been instituted against him, sensational publicity was the result, and he was asked to resign from the faculty of Johns Hopkins.  In the same year, he married Rosalie Raynor, with whom he had carried on a research collaboration in the study of infants.  Although he knew nothing of the world of business, he made contacts that in 1921 resulted in his affiliation with the New York City advertising agency of J. Walter Thompson.  He was advanced to vice-president in 1924 and remained with the company until 1936 when he went with William Esty and Company.

            He continued contact with psychology by writing popular articles for McCall's, Harper's, and Collier's magazines.  His book, Psychological Care of the Infant and Child, published in 1928, was meant for a general audience.[48]  It was almost inevitable that he would write this book.  He had a deep-seated enthusiasm for the practical value of psychology in controlling behavior and his environmentalist position demanded that infancy be seen as an extremely important formative period, for good or for ill.  Illustrative of its contents is the question of whether or not children should live in individual homes or even know their parents, since it was these parents who were the major source for faulty conditioning.  The avoidance of creating fears by adverse conditioning, the dangers of too much stroking, and the pernicious effect of the hampering of movements are illustrative of the advice he would give parents.  In the terminology of a later time, Watson very strongly aligned himself with the regulatory rather than the permissive school of child rearing.

            While in New York City, Watson secured a grant for research on the human infant, and the work was carried out by a research associate.  For a time, he lectured at the New School for Social Research.  These lectures are the basis for his book Behaviorism, a statement of his view in a form suitable for popular reading.[49]  In retrospect, Watson conceded that the book was too hastily prepared.  The revision of this book in 1930 marked, for all practical purposes,  his departure from psychology.  After the date Watson occupied himself primarily with work in the business world until his retirement in 1946.  He died in 1958.


Watson's Interpretations of Psychological Problems


            In his zeal to remake psychology, Watson attempted to apply the behavioristic approach to a variety of psychological problems.  Characteristic are his interpretations of instinct, emotion, thinking, learning and conditioning, and personality.  In their study he was guided by the concept of stimulus-response and would limit their study to psychological methods considered acceptable for research.


            Behaviorism and Stimulus-Response.  Psychology is concerned with the behavior of the whole organism.  Physiology, its closest neighbor among the other sciences, is concerned with the functioning of the parts of the body, the organ system, circulation, digestion, and the like.[50]  To reduce behavior to its simplest terms, it is found that the acts of human behavior always involve a stimulus that brings about a particular response.  This stimulus is provided by something in the environment, by movements of the muscles, or by glandular secretions.  The response follows upon the incidence of the stimulus.  If these assumptions are accepted, it follows that the task of psychology is to study the laws of behavior; thus, when given the stimulus, one may learn to predict the response, or, given the response, one may isolate the effective stimulus.  In terms of a formula, psychology was the science of S-R, where S refers to stimulus and R refers to response.  If the stimuli are of a complex character, it is appropriate to speak of the stimulus situation, which is ultimately resolvable into its component parts.  Actually, except in the rarest of instances, we are dealing with situations, not with an isolated stimulus.  Likewise, responses involve not only the simple responses that are also studied in physiology, such as the knee jerk or eye blink, but also more complex responses, to which the term "act" may be applied.  Usually, what is meant by action is that the organism responds by some movement in space, as in walking, talking, fighting, or eating.  Nevertheless, these actions reduce to two forms--motor and glandular responses.  Responses may be overt, that is, observable; or they may be explicit or nonovert, that is, nonobservable or implicit.  A person may show responses while standing apparently immobile; precise measurement would nevertheless show that muscular and glandular changes were taking place.

            Responses, besides being either implicit or overt, are either learned or unlearned.  Specification of the extent and nature of both the unlearned and learned responses is necessary.  So, too, is the discovery of the laws of acquisition of the learned responses.

            Stimulus-response units are, by an extension of their meaning in physiology, called reflexes.  They are not to be analyzed by the psychologist as minutely as they are by the physiologist.  Watson did devote attention to the structures that make  behavior possible, but he left to the physiologist the tasks of providing a detailed analysis and unraveling whatever organization takes place within the central nervous system.  Brain processes, as such, did not particularly interest him, because of the inaccessibility of the brain, that "mystery box," as he called it.[51]  Moreover, the brain had been used by earlier psychologists as the repository for whatever they could not explain in mentalistic terms.  Behavior involves the whole body, not the nervous system alone, but the muscles and glands as well.  Watson's interest was in somewhat larger segments of behavior:  what an individual would do in a given situation; for example, with what hand the infant would reach for the peppermint stick or what his response would be to a loud noise.

            While behavior of the whole organism might have been his announced goal, it is now apparent that his approach, problem by problem was still molecular in character, that is, he was guided by a belief that his behavioral data were to be described in terms of relatively small units.  He did not operate at the extreme lower level that he insisted the physiologist did, but used their units in larger assemblages. 


            Psychological Methods.  Watson championed methodological objectivism.  He explicitly states that methods used by the psychologists are:  1) observation, with and without the aid of instruments; 2) the conditioned reflex methods, both secretory and motor; 3) testing; and 4) the verbal report method.[52]  Observation is, of course, fundamental and the basis for all other methods.  How Watson would use it has been illustrated in his studies of handedness.  The conditioned-reflex method is described in a later section.  The test methods included use of both those instruments already extant and new ones developed, but their results have been treated as behavior samples to ascertain general level of behavior and special abilities.  Incidentally, intelligence as measured by tests is nothing more than the capability to form new habits according to Watson.


            Instinct.  Watson's views about instincts passed through three stages.  He started from a more or less conventional acceptance and ended with a sweeping denial of their existence in humans.  In his 1914 book on animal psychology, he devoted a considerable number of pages to discussing instinct, noting, however, that it was a much abused word.[53]  Nevertheless, he used it, characterizing it as a series of joined reflexes that unfold as heredity dictates.  By 1919, in his Psychology from the Standpoint of a Behaviorist, he argued that unlearned behavior can be seen only in young infants because this behavior is quickly overlain by habits.[54]  His position at this time was that, if we study infants, we can tease out the processes by which the complex learned behavior patterns, loosely called instincts, have developed.

            In his Behaviorism of 1925 he flatly rejected the concept of instinct for man.[55]  As evidence for his denial of instinct, he offers a catalogue of the reflex behavior repertoire of the human infant, such as sneezing, crying, smiling, turning the head, arm movements, feeding responses, crawling, walking, and handedness.  Because of slight structural differences among infants, there are equally slight but significant differences in how these reflexes are performed.  Given the individual differences and the capacity for rapid habit formation, we have the basis for what has erroneously been called inherited characteristics.

            Not only did Watson claim there were no instincts, he went further and said there were no inherited capacities, temperaments, or talents.  In so doing, Watson was taking an extreme environmentalist position.  Such was his insistence upon the plasticity of human nature that he wrote:


 Give me a dozen healthy infants, well-formed, and my own specified world to bring them up in and I'll guarantee to take any one at random and train him to become any type of specialist I might select--doctor, lawyer, artist, merchant-chief and, yes, even beggar-man and thief, regardless of his talents, penchants, tendencies, abilities, vocations, and race of his ancestors.[56]


            Actually, this extreme environmentalism is not characteristic of the behavioristic emphasis on objective content and methodology and rejection of introspection.  Although Watson's stand on instincts was part of his system, it did not follow that it was an integral part of behaviorism.  One could be a behaviorist and still reject his interpretation of environmental effect.


            Emotion.  To Watson, emotions were not matters of experienced states, but bodily reactions to specific stimuli.[57]  His most famous study was the search for the stimuli that produce emotional responses.[58]  Described objectively the stimulus situation and the responses that the stimuli brought forth.  He stimulated each infant in a variety of ways and narrowed down those eliciting emotional responses to a small number.  Watson believed he had found evidence for only three emotions in infants--fear, rage, and love.  Fear was produced only by a loud noise (made by striking a steel bar with a hammer) and by loss of support (carried out by allowing the child to drop a few inches, or by jerking his blanket).  Other situations, such as the presence of furry objects mentioned earlier, or the dark, or a snake, or the thousand and one things of which children are supposedly afraid simply did not at this young age produce fear responses.  Watson described the responses of fear as involving startle, a catching of breath followed by rapid breathing, changes in skin color, hand-clutching, puckering of lips and crying and, if the child was old enough, crawling, walking, or running away.

            The only stimulus for rage that Watson found from a wide variety of stimuli was hampering or restricting the infant's movements in one fashion or another, such as holding his head firmly or restraining his movements.  The behavior exhibited in response to this stimulus was described as stiffening of the body, holding the breath, and slashing movements of arms and legs.

            Love, not as fully investigated as the other two emotions because of the restrictions of convention, was produced by stroking of the skin, by gentle rocking, and by patting.  Smiling, cooing, and gurgling were the responses to this form of stimulation.

            These were the only unlearned emotional responses that Watson could find, although more cautiously than he is often pictured, he said that the presence of others must be left in doubt.  All other emotional reactions, he concluded, have to some extent a component of learning, largely acquired through conditioning during early childhood.  Just as the child acquires his motor skills, walking, skating, or typing, he acquires his fears, his loves, and his hates.

            Watson's findings on emotions stimulated considerable research interest in the emotional development of children, including many studies that attempted to refute his contentions.  A considerable amount of evidence has been collected that fails to confirm the existence of the specific emotional responses advanced by Watson.[59] 


            Thinking.  To Watson, the most important kind of implicit sensory-motor behavior occurs when the person stands stock still and, after a lapse of time, comes forth with a solution to some problem, the solution being expressed verbally or by some movement of the body, arms, or legs.  The implicit behavior prior to the overt action, of course, would be thinking.  To Watson, committed as he was to behavior as his datum, this implicit behavior was genuine and relevant.[60]  Thinking, he said, is only subvocal speech or muscular habits learned in overt speech that become inaudible as we grow up.  After learning to talk by conditioning, though is not more "than talking to ourselves."[61]  A bodily response is a word substitute.  A man thinks, that is, he makes implicit verbal reactions that do not differ in spirit from the overt movements made by a rat in running a maze.  Thinking, to be sure, is more implicit and more economical of time and effort, but this is a difference only of degree.  Attach recording devices to the larynx of the thinker, and we get movement that thus becomes explicit.  In a young child who is in the process of learning a language, these quantitative differences in amount of movement are even less great.  Often children, and occasionally adults, think aloud.  The child will say what he is going to do and then do it.  Under the influence of social pressure (conditioning), he learns to give up clear articulation for whispering and finally reaches the stage of inaudible or implicit speech, characteristic of the adult.  The most obvious source of evidence Watson could not use, namely, that we are sometimes introspectively aware that we do talk to ourselves while thinking.  he could hardly bolster behaviorism with an appeal to introspection!_

            Thought is not merely behavior of the larynx or subvocal talking; it involves the whole body as when we gesture, frown, or nod, or when we carry out any movement that stands for an object or a situation.  Watson suggested observing a deaf mute's fingers.  During his thinking, muscular movements of the fingers will be found, just as there are movements from the larynx of normal persons.  Failure always to get positive results from this method Watson attributed to the lack of delicacy of the instruments available.  As a matter of fact, use of improved methods has demonstrated that thinking does involve these peripheral muscular factors, but that central or brain processes have also been shown to be present by later research.  The judgment of later generations of psychologists is that Watson's theory of thinking as subvocal speech is too schematic and oversimplified.


            Learning.  Watson's views of learning showed progressive change and expansion.  In his 1913 article he conceived of behaviorism as using stimulus-response and habit formation but made no mention of conditioning.[62]  By 1916 in his presidential address he enthusiastically endorsed conditioning.[63]  In his Behavior of 1919 the available research on discriminatory maze and puzzle-box learning was described in detail.[64]  He called Thorndike's law of effect "highly figurative."[65]  Evidently, he saw conscious feeling lurking somewhere in this way of formulating the animal's responses.  Watson would have substituted recency and frequency for the influence of effect.  The successful act, over a series of trials, was that most frequently performed and, by its position within a trial, was also the one that occurred most recently.  He argued that, after all, the animal takes the correct path at least once every trial, while particular blind alleys are skipped in a given trial; the successful path occurs last and is therefore the most recent. After 1916, Watson emphasized the importance of conditioning.  The conditioned reflex became the heir of associationism.  He expressed it in contiguous conditioning or a continuation of stimuli accompanying a movement, so that, when this combination recurred, it tended to be followed by the same movement.  Watson emphasized repetition while he rejected effect and, consequently, failed to recognize the importance of reinforcement, a key concept in later conditioning theory.

            Watson's application of conditioning principles to learning in general and to thinking and emotion in particular now becomes relevant.  Habits are nothing more than complex conditioned responses, such as those involved in playing tennis, in soling shoes, or in exhibiting maternal reactions to children.[66]  These habits are integrations of conditioned responses around an activity built up from the available behavior repertoire, starting with innate movements.  Movements combine by conditioning into complex acts.  Language habits are merely a special case in that, to some extent, they become implicit.

            Conditioning is the basis of speech, and speech is the basis of thinking.  This bald summary shows why conditioning is important in thinking.  Shortly after birth the infant exhibits vocalizations that, after conditioning, are spoken words.  The vocalization of the infant of "da-da" is attached to the person of the father; through further conditioning it becomes "daddy."  With stronger verbal habits, the child no longer has to say aloud the conditioned response of, "father," selectively conditioned from the more primitive, "daddy."  Thinking it alone now suffices.  Other words and thoughts develop in a similar fashion.  Subvocal speech, or thinking, has been developed through conditioning.

            The child's fears and other emotional reactions beyond those given to unlearned responses are brought about by conditioning.  Watson and Rosalie Rayner demonstrated this contention by building up a conditioned fear in the laboratory.[67]  Their single subject, one of the most famous in psychological literature and therefore deserving of specific mention, was Albert B., a healthy, eleven-month-old infant, raised in the hospital where his mother was a wet nurse.  The only fear reactions that he showed were to loud sounds.  His reaction to anything at all coming chose enough was to reach out toward it and, if possible, to manipulate it.  This included animals, such as the white rat.  Presented here is the experiment itself, in synoptic form from their laboratory notes, faithful in spirit, but not precise in all details:


(Eleven months, 3 days)

1. Rat introduced.  A reached.  Just as hand reached, steel bar struck (not visible to A).  A jumped violently, fell forward, but did not cry.

2. Again A reached; bar again struck.  A jumped violently and whimpered. (One week allowed to lapse so as not to disturb child too seriously.)


(Eleven months, 10 days)

1. Rat presented without sound.  Steady fixation, but at first no reaching, then tentative reaching, but withdrawal as rat touched.

2-4. Combined stimulation rat and sound.  Started, no crying.

5. Rat alone.  Puckered face, whimpered and withdrew.

6-7. Combined stimulation.  Started and cried.

8. Rat alone.  Turned away, fell over, raised himself and began to crawl away rapidly.

(Eleven months, 15 days)

1. Blocks introduced.  Reached readily.

2. Rat alone, whimpered.

3. Rabbit alone.  Leaned away, whimpered and then cried.


            A conditioned fear had been established.  A rat to which Albert had previously shown no fear, now brought forth fear.  It can be inferred that such fears could inadvertently build up a home, so that a child is being conditioned when he is in bed in the dark and hears a loud clap of thunder, producing thereafter a fear of the dark.

            This study did more than demonstrate a conditioned emotional reaction:  the two research workers went beyond this to show that the conditioned fear transferred to other previously unfeared objects.  When the rabbit was introduced, Albert showed fear.  Other furry things, a dog, a fur coat, cotton, wool, and a Santa Claus mask were introduced, to which fear responses were now shown.

            If conditioning can produce fears, can conditioning also be used to eliminate them?  In another, later study "unconditioning" was compared with other methods as to its efficiency in eliminating fear responses.[68] 


            Personality.  To Watson, with his molecular predispositions, personality was a straightforward summation of activities, neither mysterious nor necessitating concepts other than those used before.[69]  All actual and potential reactions, verbal, manual, and visceral, go to make up the personality.  Personality is the end product of an individual's habit systems.  By habit systems Watson meant general, conveniently large groupings of individual habits that cluster together, constituting a useful way of talking about the various constituents of personality.  Habits are formed just as described earlier, but now they are grouped to fit the particular topic.  In a particular illustration used by Watson, shoemaking (the man's trade), religious, patriotic, marital, parental, arithmetic, general information, special fear, personal, and recreational habit systems are listed.  These, of course, are only a sampling of the habit systems that constitute a personality.  In another person, a different classification of habit systems would be used, although some of those listed are of a general character applicable to anyone.  Since the cross section is taken at a point in time, later or earlier cross sections would show differences because habits are changeable; no individual's personality remains the same throughout life.

            In this changeability of personality lies an opportunity for the betterment of mankind.  Behaviorism, Watson believed, should stimulate adults to change themselves and especially to be prepared to bring up their children in a scientific way.  Will not they "in turn bring up their children in a still more scientific way, until the world finally becomes a place fit for human habitation?"[70]




            Watson's contribution to behavioral psychology, at least in the long run was the behavioral method rather than his systematic or organizational bravado.  The behavioral psychologies which came later and dominated American psychology from the 1930's through the 1960's were tied together primarily by their emphasis on stimulus-response connections and in their treatment of responses as actions that are objectively measurable, whether they be gross muscular acts or electrophysiological responses of the finest sort.



            Watson's behaviorism was not the only objective psychology of its time, but it remains the classic example of behavioral principles that have come down to the present day.  Like Wundt's psychology, it was a starting point for later positions that would disagree with details of the founding system.  Also, there were other influences beside Watson on later behavioral developments.


Logical Positivism and Operationism 


            Just as the positivism of Comte and Mach strongly influenced earlier generations of psychologists, the neo-behaviorists were influenced by neo-positivism, usually called logical positivism or the positivism of the Vienna Circle, a philosophical position that developed in Vienna earlier in the twentieth century.   Rudolf Carnap and Herbert Feigl were major influences in the movement.  To logical positivists, for a statement to have meaning for science, it must be expressed in terms of empirical operations.  That expression will allow its unambiguous definition and it can be empirically tested.  The emphasis was on the social observability of terminology.  Questions about the nature of things were allowable only if they could be empirically observed or measured.  The position fitted in very well with the basic approach of behaviorism, which also rejected internal and subjective processes. 

            In America, Operationism was the expression of this same approach.  It was the book,  The Logic of Modern Physics, published by  Harvard physicist, Percy W. Bridgeman (1882-1961) in 1927,[71] which triggered this interest and acceptance in operational definitions.  In physical study he argued that a concept was the same as the corresponding set of operations by which it was found.  To illustrate he gave the example of length.  What is length?  To find out, we perform certain operations.  Length is defined in terms of the actions (operations) we go through to observe it.  As Bridgeman said,  "We mean by any concept nothing more than a set of operations; the concept is synonymous with the corresponding set of operations."[72]  Psychology was ready for operationism; so much so that four years before Bridgeman, E.G. Boring, reflecting an already widespread cliche', wrote a paper for a national magazine which pointed out that it could be argued that "intelligence is what intelligence tests test," an operational definition before operationism.[73]  On this and other grounds, the climate of opinion was receptive to operationism.

            S.S. Stevens, in a 1935 paper, called psychologists to adopt "an operational base of psychology."[74]  This was followed in 1939 by a book by Carroll C. Pratt that gave the history of operationism and considered its implications for psychology._  By 1939 operationism had been seized on avidly and a flood of articles began to appear.  Besides the rigor this theory introduced into psychologists' research activities, it provided a graceful retreat from the excesses of the "schools" that by this time were embarrassing psychologists.

            Operationism is wider than a behavioristic outlook.  It can be and is used in situations where conscious experience was traditionally considered to be involved, as in studied of sensation and perception, and it could even use mentalistic terms, provided they are operationally defined.  A research situation is arranged, the observer reports what he sees -- the perception is the reaction.  The subjective had been translated into the objective because they were not public operations.  From the operational reports of one investigation another research worker can go and do likewise, thus verifying or not, as the case may be, that the operations lead to the claimed result.  Operationally, consciousness becomes discriminative behavior.  Parallel to operationism was E. C. Tolman's concept of "intervening variable" which will be discussed in the section devoted to Tolman.




            Technically, any behavioral approach that came after Watson and his immediate contemporaries may be called neo-behaviorism.  The neo-behaviorists were as diverse as their forebears, but their differences as well as similarities  show how American psychology developed during the behavioral era.  For this purpose we will discuss this era in terms of four of its major contributors, Clark Hull (1884-1952), Edward C. Tolman (1886 - 1959) and B. F. Skinner (1904 - ).  Skinner may be arguably listed as being in the line of Thorndike.  Hull represented the extension of Pavlovian conditioning and Tolman represented a line with many roots, but most closely representing the behavioral extension of functionalism. 


            Clark Hull  It was during his years at Yale University that Clark L. Hull (1884-1952) carried out his collaborative investigations of learning that made reinforcement central.[75]  He had received his graduate training at Wisconsin and had taught there before moving to Yale University as a research professor in 1929.  At Yale, his weekly research seminar became one of the major training grounds for many of the those who have taught the present generation of eminent psychologists.  Either in connection with the seminar or through other means, Kenneth W. Spence, Neal Miller, John Dollard, Robert Sears, Ernest Hilgard, and O.H. Mowrer were associated with him. 

            The basic statement of the theory of behavior proposed by Hull is given in his Principles of Behavior[76] published in 1943.  It was modified in his Essentials of Behavior[77] of 1951 and extended in A Behavior System,[78] published the year of his death.

            In his autobiography, Hull stated that he:


came to the definite conclusion around 1930 that psychology is a true natural science; that its primary laws are expressible quantitatively by means of a moderate number of ordinary equations; that all the complex behavior of single individuals will ultimately be derivable as second laws from (1)these primary laws together with (2) the conditions under which behavior occurs; and that all the behavior of groups as a whole, i.e., strictly social behavior as such, may similarly be derived as quantitative laws from the same primary equations.[79]


            To implement these aims of objectivity and quantitativity, he developed statements about learning in terms of postulates, corollaries, and equations in a hypothetico-deductive framework using carefully defined symbols.  A postulate or corollary led to the formulation of empirical predictions for a particular kind of learning situation, such as multidirectional maze learning.

            After two preliminary postulates, his third had to do with the key principle of primary reinforcement.  To quote:


            Whenever an effector activity (R) is closely associated with a stimulus afferent impulse or trace (s) and the conjunction is closely associated with the rapid diminution in the motivational stimulus (Sp or Sg), there will result an increment () to a tendency for that stimulus to evoke that response.[80]


Another of his postulates, which numbered seventeen in all, had to do with habit formation, utilizing the variable of the number of reinforcements.  Others concerned primary motivation or drive, stimulus generalization, and experimental extinction.

            Hull's theoretical formulations led to many empirically testable propositions and a tremendous amount of research, which it is impossible to summarize here.  To some degree, Hull's greatest contribution to behaviorism may be the amount of research, pro and con, that his theoretical formulations stimulated.  As with all theorists, his positions were often found wanting, but Hull is one of the best examples of a theoretical psychologist who attempted to state his positions with the kind of precision that would allow their empirical test._  At last, however, his theoretical formulations had to become so complicated to take account of the various behavioral situations that it seemed to break down under its own weight.

            Each of Hull's major students carried the behavioral approach beyond him and into different areas of psychology.


            Kenneth W. Spence (1907 - 1967) was perhaps Hull's most direct successor in behavior theory.  Spence was not only Hull's successor but was an active and stimulating collaborator during Hull's later career.[81]  At first Spence concentrated on discrimination learning; then he turned to the investigation of the assumptions of a theory he had formulated concerning very simple learning.[82] While Hull had attempted to find formulations to cover all behavior, Spence limited his theoretical structures to more tightly definable experimental situations. 

            Another of Hull's major students, Neil Miller (     ) also moved away from Hull's attempt to produce a detailed but global theory of behavior.  Miller chose a less theoretical and more problem-oriented approach to the study of behavior.  This is not to say that Miller was non-theoretical, but his theories were directed to specific problem areas.  His work in conflict, displaced aggression and learned drives are examples of this problem-oriented theoretical approach.[83]  He extended behavior theory into social learning, imitation and even to personality and psychotherapy, with a fruitful collaborator, John Dollard.[84]


            Edward C. Tolman (1886-1961).  Tolman is more difficult to place in the behavioral framework, although his significance to the development of behavioristic psychology is undoubted. Is he a neo-behaviorist or one of the contemporaries of Watson, such as Hunter?  Because his contribution to behavioral psychology involves developments that came onto the scene after the early work of Watson, we are classifying Tolman as a neo-behaviorist. 

            Tolman was devoted to research on learning more or less independent of the prevailing schools of thought of his time.  But his behaviorism, his molarism, and his purposiveness outweigh his contributions to the cognitive theory of learning, which has variously been described as involving sign-Gestalts, sign-significances, or expectancies.  According to his autobiographical statement, he stressed in his work not learning, but a formulation of these other concepts.  This was done, however, in a fashion much less militant and strident than the earlier generation of behaviorists.   In many respects, Tolman could be considered as much of a neo-functionalist as a neo-behaviorist, although as one gets further away from the first generation of behaviorists and functionalists, the difference between these two positions begins to blur. He showed the influences of a number of lines of thought, including the purposivistic psychology of McDougall and the molaristic approach both of Chicago functionalism and  Gestalt psychology.[85] 

            Tolman had been a graduate student at Harvard.  In the main, his training had been in the Titchenerian vein and his encounter with Watson's Behavior in Robert M. Yerkes' course in comparative psychology was both a stimulus and a relief, for he had already been troubled about the inadequacies of introspection.  He took his degree in 1915 and in 1918 moved to the University of California at Berkeley where he remained.  On arriving at Berkeley, his choice of a new course to teach was comparative psychology and he was soon embarked on research in learning in rats.  He concluded that Watson held oversimplified notions of stimulus and response and, influenced by his exposure to Gestalt psychology (he had spent some time in Giessen with Kurt Koffka, one of the leaders of Gestalt psychology), he began to develop his particular views of psychology.  Since he conceived of psychology as dealing with something larger than muscle contractions -- with behavior as behavior, as he stated it -- it was not surprising that he borrowed from his philosophy professor at Harvard, R.B. Perry, the notion  that purpose and cognition, while essential to understanding behavior, can still be basically descriptive.  Tolman was also influenced while at Harvard on reading McDougall's Social Psychology and other works that represented McDougall's particular brand of purposive, functional type of psychology. 

            These influences as well as logical positivism, led Tolman to develop his own view of behavior.  In 1932 he published his Purposive Behavior in Animals and Men.[86]  One should say immediately that "purposive" was being used in a descriptive rather than teleological way.  In more detail, he saw purpose as an urge to get to or away from a type of goal object, shown by persistence and the tendency to use the shortest route.  By taking this position, he was calling attention to such matters as the readily observable fact that if on reaching the food box the rat finds no food, he tries other ways of finding it.  A series of trials, not a single trial, shows that blind alleys are eliminated and the shortest possible route is finally adopted -- the animal is learning a route to a goal, the means to an end.  "Learning the maze" is for Tolman decisive evidence of goal seeking.  This definitely was not a teleological use of the term.  In contrast to molecular behavior, which had to do with the underlying physiological activity, Tolman emphasized the molar behavior of men and animals acting in respect to ends. 

            Tolman made use of the concept of "intervening variables" in dealing with behavioral explanation.  Tolman had mentioned "operational behaviorism" as representing his view as early as 1936.[87]  His views on operationism paralleled those of S. S. Stevens.   The central theme of Tolman's paper was the functional and mathematical dependencies of "intervening variables" on the other variables.  He then pointed out the necessity of using operational means of specifying these intervening variables.  Discussion of intervening variables in his presidential address before the American Psychological Association, published in 1938,[88] gave his position the wider audience his earlier paper had lacked.  Thereafter, the concept of intervening variables was integrated with operationism in a way that made the two central to theoretical endeavors of the time.  In 1948, Kenneth MacCorquodale and Paul E. Meel[89] published an extremely significant paper that attempted ( and, as later events showed, in some measure succeeded) in bringing order into this confusion of terms.  They made the distinction between hypothetical constructs which involve hypothesizing a process or event that is not itself observable (such as events within the nervous system), and intervening variables that do not involve such hypothetization but abstract the empirical relationships without surplus meaning being involved.

            Tolman, more than others represents the neobehaviorist position.  He shared the widely held opinion that "grandiose" systems, such as his own, are at least temporarily out of step with the present.  His title for his article in the Koch volumes is the "Principle of Purposive Behavior," but the article is devoted almost exclusively to specification of his position on learning.  There is no mention of behaviorism as a system other than his skeptical comment just mentioned.  The structure of his system is stated in terms of independent variables (past and present), intervening variables (demand variables such as means to an end readiness, expectation, and cognitive variables such as perceptions of objects and recognition of previously perceived places), and dependent variables.   His intervening variables, he cheerfully admits, share in the surplus meaning of the hypothetical constructs as the term is used by MacCorquodale and Meehl.

            Tolman's purposive behaviorism was at odds with the straight line associationism of Watson's behaviorism and with Thorndike's connectionism.  He was, during the 1940's, the primary alternative to Hull's form of behaviorism.


            B.F. Skinner and Radical Behaviorism.  Burrus Frederick Skinner (1904 - ) more than any of the behaviorists may be seen as the founder of a school of behavioral psychology.[90]  His form of behaviorism has continued to be more militant than the other forms we have seen.  His behaviorism attempts to be a descriptive discipline, avoiding theories of behavior.  Having once accepted intervening variables,[91] even this form of hypothesis was rejected in his Science and Human Behavior of 1953.[92]  Skinner is thus the representative in the twentieth century of Francis Bacon's approach to scientific inquiry.  The variables we have available for scientific analysis, Skinner tells us, are operations performed on the organism from without, such as water deprivation and a kind of behavior, say, drinking.  The inner condition "thirst" (what would be called a hypothetical construct) is useless in trying to control behavior because we cannot manipulate it as we can the operation from without, that is, the water deprivation.  Skinner would do away with all such intermediaries entirely.[93]  Since theories depend upon these intermediaries, it is quite logical that he would also dispense with theories.  Psychology as a field, he holds, is still inadequate for theorizing and we must collect much more data.  The nearest approach to a theory he tolerates is the assumption that there is order to be found in behavioral data.  Needless to say, Skinner rejects the hypothetico-deductive theoretical approach accepted by Tolman, Hull and their intellectual successors.  An understanding of behavior is not to be found in comparing theoretical constructs with data but in meticulous description of the antecedent conditions and the behavioral results.[94] 

            Skinner and his followers have emphasized the technique of collecting large amounts of data on a small number of subjects.  The analysis of the behavior of individuals is preferable to the averaging of the data gathered on multitudes.  The use of statistical analyses, he believes, tends to lose the very events one is attempting to study.

            Skinner's behaviorism seeks functional relationships between stimuli, broadly defined, and behaviors.  The technique employed to discover these antecedent-consequent relationships is operant conditioning, or instrumental conditioning.  The relationship of Skinnerian instrumental conditioning to Thorndike's methodology employed in his as "trial and error learning" in his cat box experiments is similar in spirit but quite different in detail. 

            Skinner's use of schedules of reinforcement is perhaps his greatest single contribution to behavioral psychology.  The different schedules are precisely defined environmental histories.  The degree to which they lead to different behavioral outcomes, both in modes of responding and in resistance to extinction, is essential to the descriptive, functional relationships that underlay Skinner's entire behavioral position. 

            Skinner's emphasis on the relationship between individuals' environmental history and their consequent behaviors has led Skinner far afield from the pigeon box.  The fact that behaviors can be shaped, that is, elaborate conditioned behaviors may be constructed by reinforcing parts of the behavior, places Skinner in the class of elementistic behaviorists, reminiscent of John B. Watson. Such behavioral shaping has applied consequences.  Skinner developed a system during World War II in which pigeons were trained to keep a target in the center of a cross-hair guidance system.  Mounted in gliders, these birds would have been the equivalent of modern guidance computers.  Once locked in on a target, they would manipulate the glider by pecking one side or the other of the target until the glider, armed with an explosive, crashed onto the target.  The technique was never put into effect.[95]  The same technique has been used in the training of animals to do tricks and entertain.[96]

            More seriously, reinforcement techniques originated by Skinner and his students have found wide application in present-day psychology.  Programmed learning has been widely used in educational situations.[97]

            Another application of operant techniques has been in clinical psychology in the form of behavior modification and behavior therapy.  Such techniques have been used for simple problems such as hiccoughs and nervous tics to use in catatonic schizophrenics and autistic children.

            In some respects, Skinner and his followers have realized the hope of John B. Watson in effecting not only prediction but also control of behavior.  Like Watson, Skinner has promoted behavioral psychology as an essential component in remaking society.  Skinner's novel Walden Two represents his idea of what society might be like with the concerted application of Skinnerian behaviorism.[98]  Skinner, however, seems to recognize the problem that Watson ignored, who controls the controller.  Skinner has admitted that "...a science of behavior is just as dangerous as the atom bomb.  It has the potential of being horribly misused."[99]


            Lashley and Physiological Psychology.  Karl S. Lashley (1890-1958)[100] .  He had studied with John B. Watson at Johns Hopkins, although he received his doctorate with H.S. Jennings in zoology in 1914.  He worked with the psychiatrist Adolf Meyer there as well.  Although his major degree work was in biology he worked more with Watson than with his major professor.  After graduation, he decided that psychology was the career of choice.  He stayed on after graduation with a scholarship and worked with Watson between 1915 and 1917.  It was during this time that Lashley came into contact with S. I. Franz, then at St. Elizabeth's Hospital in Washington.  In 1917, Lashley published two papers with Franz on the effects of brain damage on learning in the rat,[101] which are exemplary of his own later work.  

            The way for Lashley's work was prepared by Shepard Ivory Franz[102] (1874-1933).  Around 1900, Franz had combined the method of studying animal learning with that of the surgical extirpation of brain tissue which he used in a series of studied.  Typical was his study "Variations in the Distribution of the Motor Centres" published in 1915.[103]  In the study he attacked that most firmly established of all "facts" of localization, Frisch and Hitzig's localization of motor functions (000).  His results showed that there was considerable lack of precision to cerebral localization.  His findings, however, were seen as hardly more than negative; no more general significance was attached to them.

            Research performed by Karl S. Lashley (1890-1958), first with Franz at St. Elizabeth's Hospital, then at the University of Minnesota, and finally under the auspices of the Behavior Research Fund in Chicago, led to his appointment at the University of Chicago, and in 1935 to a call to Harvard.[104] 

            What was the research that brought on his rapid academic rise, to say nothing of the presidency of the American Psychological Association and membership in the National Academy of Science before he was forty years of age?  It concerned the effect of differential extirpation of the rat's cerebral cortex on intelligence (defined here as learning ability). Lashley saw behavior as a biological problem and felt that biological methods, including surgery, were appropriate in its study.  To appreciate the significance of this problem, it is necessary to refer to the neurophysiological interpretation  of learning then current.  At that time, learning in the nervous system was seen as a matter of isolated neurones and synaptic resistances forming reflex paths with detailed localization of function in  the cerebral cortex.  The accepted rough model of the brain's function was that of the electrical switchboard.  Changes at the synapses in a network of neurones had come to be the physiological equivalent of what started at the psychological level as association of ideas.  It still was a strongly molecular point of view.  Begun about 1920, Lashley's research culminated in his 1929 publication, Brain Mechanisms and Intelligence.[105]  In it, he reported overwhelming evidence for much less localization of function in the cortex than had heretofore been accepted and further demonstrated that large lesions affect learning more than small lesions.  For these results, he supplied a conceptual framework involving "equipotentiality" and "mass action."  Equipotentiality is the capacity of the intact portion of the brain to continue to carry out the function previously served by it and the extirpated part of the functional area.  Mass action, while indicating a functioning of an area as a whole, serves as a reminder that there can still be proportional reduction of efficiency in complex functions.  The reduction is in proportion to the extent of the injury.  Considerable evidence for modes of organization rather than isolated single specific pathways and reactions was found in a series of experiments.  In short, Lashley rejected at the physiological level the simple stimulus-response connectionism of Watson and Thorndike.[106]

            A widespread misconception of the significance of Lashley's results came about partly because of Lashley's manner of presenting them. He was interpreted as saying that what happens in the nervous system is guided by mass action, that when any area of the cortex is removed, another area can carry out its functions.  What, under this interpretation, is left for physiological psychology to do?  Based on a general acquaintance with his findings, an antiphysiological trend set in, and psychologists lost interest in physiological research, even coming to see the nervous system as irrelevant to psychology.  "Behavior theorists," to use a loose but sufficiently apt term, could trace part of their skepticism concerning physiology directly back to Lashley's work.

            This loose interpretation of Lashley's results has ignored what a more careful examination would have shown.  Lashley was not denying localization.  What he was saying was that localization was both less precise than and different from what previously had been conceived -- and considerably more complicated.  In some cases equipotentiality held; in others, it did not.  Mass action was not always a factor.  Mass action and equipotentiality are more evident in complex problems and less so in simple ones, which leaves plenty of scope for physiological-psychological research.

            The disappointment with the results of Lashley's experiments and Lashley's own argument that psychologists should stay away from neurologizing[107] had actually retarded development of physiological research within psychology. The understanding of an alternative to simple stimulus-response networks had to await Donald Hebb.


            Hebb and Cell Assembly Theory.  D. O. Hebb (1904 - 1985) probably did more than any other individual to re-establish modern physiological psychology as a part of behavior theory.  Hebb was a Canadian, born in Nova Scotia.  He received his bachelors degree at Dalhousie.  He taught for a while in public school.  In 1929 he entered McGill university part time.  He received his MA degree there in 1932.  At McGill he worked with two of Pavlov's students, Boris B. Babkin and Leonid Andreyev.[108]

            His conditioning work gained him an offer from Robert M. Yerkes of Yale.  Instead, Hebb went to Chicago to study with Karl Lashley.  When Lashley went to Harvard in 1935, Hebb went with him, completing his doctorate with Lashley there in 1936.  His dissertation with Lashley dealt with the discrimination of size and brightness by rats reared in total darkness.[109]

            Hebb worked with Lashley an additional year after his dissertation.  In 1937 he returned to Canada as fellow of the Neurologial Institute in Montreal.  There he worked with brain surgeon Wilder G. Penfield (1891-1976), an experience that would influence much of Hebb's later life and research. The problem of intelligence and brain damage which had dominated Lashley's work was being done by Penfield and his staff, but this time with humans.[110]   After a short stint at Queens University in Ontario, he spent the years 1942-1947 at the Yerkes Laboratories of Primate Biology in Orange Park, Florida.  It was at Yerkes' laboratory that Hebb noticed the emotional response elicited by chimpanzees on seeing a clay model of a chimpanzee's head.  This response could be elicited by any detached body member such as a hand.  Their response also extended to humans, since they reacted to a mannequin hand.  Since this emotional response increased with age.  This and other experiences dealing with the personalities of the chimps led Hebb away from the "hard-boiled" view of behavior theorists who rejected talking of such things in animals as "mentalistic."[111]  Many years later he would write on this in an article titled "The Social Significance of Animal Studies."[112]

            Hebb continued to deal with the problem of human intelligence and brain action.  It was in 1944 that he hit upon the position that would come to be known as Cell Assembly Theory. Hebb tells us:


...I found out that Rafael Lorente de Nó had recently shown:  (1) that reentrant or closed circuits were to be found throughout the brain, which thus was no longer to be seen as a through-transmission, sensorimotor mechanism, but as one capable of a purely internal activity  also, as a possible basis of thought; and (2) that one neuron by itself may not be able to excite a second neuron at the synapse, but can do so if supported by simultaneous action from another neuron.  (That is, two presynaptic neurons can be effective when one is not, which, in principle, offers an explanation of the selective effect of attention, when some activity that is going on in the cortex provides such support for one sensory input but not for another.)  The first idea offered a solution for my earlier problem, What is a concept? -- namely, that it is a group of cortical neurons exciting and reexciting each other.  The second idea was a fascinating one, for attention and set had been a complete mystery up to that time... and now I had a possible solution.[113] 


Hebb was now looking at thought "as a sequence of brain events, each excited jointly by the preceding event and by the sensory stimulation of the moment.  The schema implied that thought must be disrupted in a strange environment with unfamiliar contingencies:  A being accompanied by C instead of the usual B."[114]  It was then that Hebb thought back to the chimpanzees at Yerkes's laboratory and their fear reactions to dismembered organs.  He came to the view that "emotional disturbance is a disruption of thought due to a conflict with environmental events or to a lack of usual sensory support....[115]

            This notion would become part of Hebb's Cell Assembly Theory.  Hebb returned to Canada with a professorship at McGill in 1947.  At that time, most behavior theorists ignored physiology.  Hebb later assessed the situation in the late 1940's as follows:


Positivism and the black box were the style, Hull avoiding and Tolman and Skinner denouncing any involvement with the brain.  Apart from Lashley's lab, only Frank Beach's and Harry Harlow's that I knew of did much physiologically.[116]


Hebb's influential book, The Organization of Behavior[117] appeared in 1949, which detailed his theory.  The significance of cell assembly theory is that it provided a theoretical structure for research, not only in physiological psychology but in behavioral psychology as well.  For this reason, Hebb is included as one of the primary post-war behavior theorists.   His theory went beyond only one area, however, and did much to stimulate research in a number of areas.

            Two concepts are important in Hebb's theory, cell assemblies themselves and phase sequences.  A cell assembly is a group of neurons that are clustered together functionally.  This functional clustering has resulted because of a past history of being stimulated together.  Their main characteristic is that they are capable of acting together for a time as a closed system.  They may have been produced through some sensory event or they may have been aroused by some previously existing assembly. One cell assembly may activate another assembly. Patterns of these mutual activations represent central facilitation which is Hebb's nucleus for the function of attention.  The cell assemblies that are activated at the same time may become organized into "phase sequences," which are a sequence of cell assembly functions.  Taking the child as his subject, Hebb tells us that when a baby hears footsteps: assembly is excited; while this is still active, he sees a face and feels hands picking him up, which excites other assemblies -- so that "footsteps-assembly" becomes connected with "face assembly" and the "being-picked-up assembly."  After this has happened, when the baby hears footsteps only, all three assemblies are excited; the baby then has something like a perception of a mother's face and the contact of her hands before she has come in sight -- but since the sensory stimulations have not taken place, this is ideation or imagery, not perception.[118]


            Hebb pointed away from the straight-line connectionistic approach which explained behavior as a simple stimulus-response chain.  The serial model or connectionist approach was held by associationists for centuries, including their modern counterparts in behavior theory such as John B. Watson and E. L. Thorndike.  Hebb held that "Neural transmission is not simply linear, but apparently always involves some closed or recurrent circuits; and a single impulse cannot ordinarily cross a synapse -- two or more must act simultaneously, and two or more afferent fibers must, therefore, be active in order to excite a third to which they lead."[119] The reflex-arc is not a simple loop but one that may have many loops built into it, some of which may be recurrent or reverberatory in nature and others of which are simply closed.  He also opposed the notion that the nervous system was a passive transmitter of sensory information from receptors.  This he denies on the basis that the central nervous system may be activated without external stimulation. 

            These are broad notions, although explicated in terms of physiological structures and processes.  In spirit it is in line with other attempts of explanation using hypothetical nervous processes, such as William James's physiological explanation for the stream of thought.[120]  Like James' notion, Hebb's cell assembly theory excited a considerable interest in physiological processes underlying mental and behavioral events.  As we will see, Hebb was also, in a way, one of the stimuli in the coalescence of cognitive psychology. 




            With the rise of behaviorism, the prescription of both methodological and contentual objectivism came to dominate the psychological scene.  This is not to say that the study of sensation, perception and its allied topics disappeared with the appearance of Watson's behaviorism or even the neo-behaviorists.  Even these traditional topics came to be studied different, however.  Introspection, both in the elaborate form used by Titchener and in the more restricted form used by the functionalists began to fade, however.  By the late 1930's, such studies involved more objective methodology such as discrimination tasks and threshold tasks.  Even sensory and perceptual psychology became more quantitative and far less qualitative. 

            The behaviorisms and neo-behaviorisms differed among themselves just as much as the orthodox introspectionistic psychologies had done.  There were as many behaviorisms as there were behaviorists.  What they shared, however, was an attempt to use objectifiable concepts and to make the acceptable psychological terms empirically definable and measurable. 



[1]Raymond Dodge published his paper as "The Theory and Limitations of Introspection,"  American Journal of Psychology 23 (1912): 214-229.

[2]Walter B. Pillsbury, Essentials of Psychology. (New York: Macmillan, 1911).

[3]J. B. Watson, "Psychology as a Behaviorist Views It,"  Psychological Review, 20 (1913):  158-177 (Herrnstein and Boring, Excerpt No. 94).




[7]Franz Samelson, "The Struggle for Scientific Authority:  The Reception of Watson's Behaviorism 1913 - 1920,"  Journal of the History of the Behavioral Sciences 17 (1981): 399-425.  For developments in the twenties, see Samelson, "Organizing for the Kingdom of Behavior:  Academic Battles and Organizational Policies in the Twenties,"  Journal of the History of the Behavioral Sciences 21 (1984): 33-47.

[8]E. B. Titchener, "On `Psychology as the Behaviorist Views It'," Proceedings of the American Philosophical Society, 53 No. 213 (1914), 1-17.

[9]J. B. Watson, Behaviorism, 2nd ed. (New York:  W. W. Norton, 1930).

[10]I. M. Sechenov, "Refleksy golovnogo mozga," trans. as "Reflexes of the Brain," by A. A. Sobkov, in I. M. Sechenov, Selected Works (Moscow and Leningrad:  Gozmedizdat, 1935), pp. 264-322 (1863) (Herrnstein and Boring, Excerpt No. 63).

[11]I. P. Pavlov, Selected Works, ed. K. S. Kostoyants, trans. S. Belsky (Moscow:  Foreign Languages Publishing House, 1955) (1873-1936).

[12]Sechenov, Selected Works.

[13]Pavlov, Selected Works.

[14]I. P. Pavlov, "Autobiography," Selected Works, pp. 41-44 (undated); B. P. Babkin, Pavlov, a Biography (Chicago:  University of Chicago Press, 1949).

[15]I. P. Pavlov, Lectures on Conditioned Reflexes, 3rd ed., trans. W. H. Gantt (New York:  International Publishers, 1928) (1904).


[17]I. P. Frolov, Pavlov and His School (London:  Kegan Paul Trench, Trubner, 1937).

[18]Pavlov, Selected Works, pp. 76-80 (Herrnstein and Boring, Excerpt No. 101).

[19]Lectures, p. 219.


[21]A. L. Schniermann, "Bekhterev's Reflexological School," in C. Murchison, ed., Psychologies of 1930 (Worcester:  Clark University Press, 1930), pp.  221-242.

[22]V. M. Bekhterev, General Principles of Human Reflexology, trans. 4th Russian  ed. (New York:  International Publishers, 1932) (1907).

[23]E. L. Thorndike, "Edward Lee Thorndike," in C. Murchison, ed., A History of Psychology in Autobiography (Worcester:  Clark University Press, 1936), III, pp. 263-270; Geraldine M. Joncich, The Sane Positivist:  A Biography of Edward L. Thorndike (Middletown, Conn.:  Wesleyan University Press, 1968).

[24]Pavlov, Lectures on Conditioned Reflexes.

[25]E. L. Thorndike, "Animal Intelligence:  an Experimental Study of the Associative Processes in Animals,"  Psychological Review Monograph Supplement 2 (1898):  No. 4. (Herrnstein and Boring, Excerpt No. 97).

[26]E. L. Thorndike, The Elements of Psychology (New York:  Seiler, 1905), p. 203.

[27]E. L. Thorndike, The Fundamentals of Learning (New York:  Teachers College, 1932); E. L. Thorndike, The Psychology of Wants, Interests, and Attitudes (New York:  Appleton, 1935). An excellent collection of Thorndike's papers is his Selected Writings From A Connectionist's Psychology (New York: Appleton-Century-Crofts, 1949).

[28]R. M. Yerkes, "The Formation of Habits in the Turtle,"  Popular Science Monthly, LVIII (1901):  519-525 (Herrnstein and Boring, Excerpt No. 98).

[29]W. S. Small, "Experimental Study of the Mental Processes of the Rat, II," American Journal of Psychology, 12 (1901):  206-232 (Herrnstein and Boring, Excerpt No. 99).

[30]J. Loeb, Einleitung in die vergleichende Gehirnphysiologie und vergleichende Psychologie mit besonderer Berucksichtigung der wirbellosen Thiere     (Leipzig:  Barth, 1899) (English trans. 1900) (Herrnstein and Boring, Excerpt No. 89).

[31]J. B. Watson, Behavior: An Introduction to Comparative Psychology (New York:  Henry Holt, 1914), p. 8.


[33]G. Bergmann, The Contribution of John B. Watson,"  Psychological Review, LXIII (1956):  265-276.

[34]J. M. Cattell, "The Conception and Methods of Psychology," Popular Science Monthly, LXVI (1904):  175-186.

[35]W. McDougall, Physiological Psychology (New York:  Macmillan, 1905).

[36]Cattell, "Founding."

[37]Paul Fraisse, "French Origins of the Psychology of Behavior:  The Contribution of Henri Piéron," Journal of the History of the Behavioral Sciences, 6 (1970): 111- 119.

[38]J. B. Watson, "John B. Watson,"  C. Murchison, ed., A History of Psychology in Autobiography (Worcester:  Clark University Press, 1936):  III, 271-281; R. S. Woodworth, "John Broadus Watson:  1878-1958," American Journal of Psychology, 72 (1959):  301-310. An excellent biography of Watson is Kerry W. Buckley, Mechanical Man:  John Broadus Watson and the Beginnings of Behaviorism. (New York:  Guilford Press, 1989).

[39]J. B. Watson, Psychology from the Standpoint of a Behaviorist, 3rd ed. rev. (Philadelphia:  Lippincott, 1929), preface.


[41]Watson, Behavior.

[42]Psychology as a Behaviorist Views It.

[43]E. B. Titchener, A Textbook of Psychology (New York:  Macmillan, 1909).

[44]Watson, Behavior, p. 3.

[45]J. B. Watson, "The Place of the Conditioned-Reflex in Psychology," Psychological Review, XXIII (1916):  89-117.

[46]Watson, Behaviorism.

[47]J. B. Watson, Psychology from the Standpoint of a Behaviorist (Philadelphia: Lippincott, 1919).

[48]J. B. Watson, Psychological Care of Infant and Child (New York:  Norton, 1928).

[49]Watson, Behaviorism.

[50]Ibid, Watson, Psychology, 1929.

[51]Watson, Behaviorism, p. 49.

[52]Watson, Psychology, 1929.

[53]Watson, Behavior.

[54]Watson, Psychology, 1919.

[55]Watson, Behaviorism.

[56]Ibid., p. 104.


[58]Watson and J.J.B. Morgan,  "Emotional reactions and psychological experimentation,"  American Journal of Psychology, 1917, 28, 163-174.

[59]M. Sherman, "The Differentiation of Emotional Responses in Infants," Journal of Comparative Psychology, VII (1927), 265-284, 335-351.

[60]Watson, Behaviorism; Psychology, 1929.

[61]Watson, Psychology, 1929, p. 238.

[62]M. F. Washburn, "Introspection as an Objective Method,"  Psychological Review, XXIX (1922):  89-112.

[62] Watson, Psychology as the  Behaviorist Views It.

[63]Watson, "Place of Conditioned-Reflex."

[64]Watson, Behavior.

[65]Ibid., p. 256.

[66]Watson, Behaviorism.

[67]J. B. Watson and R. Rayner, "Conditioned Emotional Reactions,"  Journal of Experimental Psychology, III (1920):  1-14.

[68]Watson, Behaviorism.


[70]Ibid., p. 304.

[71]P.W. Bridgeman, The Logic of Modern Physics (New York: Macmillan Company, 1927).

[72]Ibid., p. 36.

[73]E.G. Boring, "Intelligence as the Tests Test It," New Republic 34 (1923): 35-36.

[74]S.S. Stevens, "The Operational Basis of Psychology,"  American Journal of Psychology 47 (1935): 323-330.

[75]C.C. Pratt, The Logic of Modern Psychology (New York: Macmillan Company, 1939).

[75]Clark L. Hull, "C.L. Hull," in Boring, et al., eds., A History of Psychology in Autobiography, (New York: Appleton-Century-Crofts, Vol. ;IV, pp. 143-162. 

[76]Clark Hull, Principles of Behavior:  An Introduction to Behavior Theory (New York: Appleton-Century-Crofts, 1943).

[77]Hull, Essentials of Behavior (New Haven, Conn.: Yale University Press, 1951).

[78]Hull, A Behavior System:  An Introduction to Behavior Theory Concerning the Individual Organism (New Haven, Conn: Yale University Press, 1952).

[79]Boring, et al., A History of Psychology in Autobiography, Vol. IV,  p. 155.

[80]Hull, A Behavior System, pp. 5-6.

[81]An excellent collection of Hull's papers is Abram Amsel and Michael E. Rashotte, eds.  Mechanisms of Adaptive Behavior: Clark L. Hull's Theoretical Papers, with Commentary. (New York: Columbia University Press, 1984).

[81]Howard H. Kendler, "Kenneth W. Spence:  1907 - 1967," Psychological Review 74 (1967): 335-341.

[82]Kenneth Spence, Behavior Theory and Conditioning (New Haven, Conn.: Yale University Press, 1956); Behavior Theory and Learning:  Selected Papers (Englewood Cliffs, N.J.: Prentice-Hall, 1960); H. W. Kendler and J.T. Spence, eds., Essays in Neobehaviorism: A Memorial Volume to Kenneth W. Spence (New York: Appleton-Century-Crofts, 1971).  For an excellent review of the Hull-Spence approach, see F.A.Logan, "The Hull-Spence Approach," in Sigmund Koch, ed., Psychology: A Study of A Science, Vol. 2, General Systematic Formulations, Learning and Special Processes (New York: McGraw-Hill, 1959), pp. 293 - 358.

[83]Neal E. Miller, "Liberalization of Basic S-R Concepts:  Extensions to Conflict Behavior, Motivation and Social Learning. In Koch, ed., Psychology: A Study of A Science, Vol. 2, pp. 196 - 292; "Experimental Studies in Conflict," In J. McV. Hunt, ed., Personality and the Behavior Disorders (New York: Ronald Press, 1944); Theory and Experiment Relating Psychoanalytic Displacement to Stimulus-Response Generalization," Journal of Abnormal and Social Psychology, 43 (1948): 155-178; Learnable Drives and Rewards, In S.W. Stevens, ed., Handbook of Experimental Psychology (New York: John Wiley & Sons, 1951), 435-472.

[84]Miller and John Dollard, Social Learning and Imitation (New Haven, Conn: Yale University Press, 1941); Dollard and Miller, Personality and Psychotherapy. (New York: McGraw-Hill, 1950).

[85]E.C. Tolman, "Edward Chace Tolman," in Boring, et al., eds., A History of Psychology in Autobiography, Vol. IV, pp. 323-339.

[86]E.C. Tolman, Purposive Behavior in Animals and Men (New York: Century Book Company, 1932).

[87]Tolman, "Operational Behaviorism and Current Trends in Psychology," Proceedings of the 25th Anniversary Celebration of the Inauguration of Graduate Studies at the University of Southern California (Los Angeles: University of Southern California Press, 1936), pp. 89-103.

[88]E.C. Tolman,"The Determiners of Behavior at A Choice Point,"  Psychological Review 45 (1938): 1-41.

[89]K. MacCorquodale and P.E. Meehl, "On a Distinction Between Hypothetical Constructs and Intervening Variables,"  Psychological Review 60 (1948): 95-157.

[90]Skinner has given us excellent and exhaustive accounts of his life.  See, B. F. Skinner, Particulars of My Life (New York: Alfred A. Knopf, 1976); The Shaping of a Behaviorist (New York: Alfred A. Knopf, 1979); A Matter of Consequences (New York: Alfred A. Knopf, 1983).

[91]B. F. Skinner, The Behavior of Organisms: An Experimental Analysis (New York:  Appleton-Century-Crofts, 1938)

[92]Skinner, Science and Human Behavior (New York: Macmillan, 1953)

[93]Skinner, "Behaviorism at Fifty," Science, 140 (1963): 951-958; also in Trenton Wann, ed., Behaviorism and Phenomenology: Contrasting Bases for Modern Psychology (Chicago: University of Chicago Press, 1964), pp. 79-108.

[94]Skinner, Contingencies of Reinforcement:  A Theoretical Analysis (New York: Appleton-Century-Crofts, 1969).

[95]Skinner, "Pigeons in a Pelican," American Psychologist, 15 (1960), 28-37.

[96]K. Breland and M. Breland, Animal Behavior, (New York: Macmillan, 1966).

[97]Skinner, "Teaching Machines," Science, 128 (1958), 969-977; F. S. Keller and J.G. Sherman, PSI: The Keller Plan Handbook (Menlo Park, CA: Benjamin, 1974); Skinner did not originate teaching machines, however.  See, Ludy Benjamin, "A History of Teaching Machines," American Psychologist, 43 (1988): 703-712.

[98]Skinner, Walden Two (New York: Macmillan, 1948).

[99]Skinner, in Richard I. Evans, B.F. Skinner: The Man and His Ideas (New York: Putnam, 1968), p.  .

[100]D.O. Hebb, "Karl Spencer Lashley:  1890 - 1958,"  American Journal of Psychology, 72 (1959) 142-150.

[101]S.I. Franz and K. S. Lashley, "The Retention of Habits by the Rat after Removal of the Frontal Portion of the Cerebrum," Psychobiology, 1 (1917) 3-18; The Effects of Cerebral Destruction upon Habit-formation and Retention in the Albino Rat," Psychobiology, 1 (1917) 71-139.

[102]S.I. Franz, "Shepard Ivory Franz," in C. Murchison, ed., A History of Psychology in Autobiography (Worcester, Mass.:  Clark University Press, 1932), Vol. II, pp. 89-113.

[103]S.I. Franz, "Variations in the Distribution of the Motor Centres," Psychological Monographs #19, 81 (1915).

[104]D.O. Hebb, "Karl Spencer Lashley

[105]K.S. Lashley, Brain Mechanisms and Intelligence: A Quantitative Study of Injuries to the Brain. (Chicago: University of Chicago Press, 1929).

[106]For an understandable but generally ignored article by Lashley on this topic, see Lashley, "The Problem of Serial Order in Behavior," in Lloyd A. Jeffress, ed., Cerebral Mechanisms in Behavior: The Hixon Symposium, (New York:  John Wiley & Sons, 1951), pp. 112-136.

[107]Karl Lashley, "Basic Neural Mechanisms in Behavior," Psychological Review, 73 (1930), 1-37.

[108]E. R. Hilgard, Psychology in America:  A Historical Survey (New York:  Harcourt Brace and Jovanovich, 1987), p.437.

[109]Hebb, "The Innate Organization of Visual Activity:  I.  Perception of Figures by Rats Reared in Total Darkness,"  Journal of Genetic Psychology, 51 (1937): 101-126; "The Innate Organization of Visual Activity:  II.  Transfer of Response in the Discrimination of Brightness and Size by Rats Reared in Total Darkness."  Journal of Comparative Psychology, 24 (1937): 277 - 299.

[110]Hebb, "D.O. Hebb," p. 290.; "Intelligence in Man after Large Removals of Cerebral Tissue:  Report of Four Left Frontal Lobe Cases," Journal of Genetic Psychology, 21 (1939) 73-87; Intelligence in Man after Large Removals of Cerebral Tissue:  Defects following Right Temporal Lobectomy.  Journal of Genetic Psychology, 21 (1939) 437-446; Hebb and Penfield, "Human Behavior after Extensive Bilateral Removal from the Frontal Lobes," Archives  of Neurology and Psychiatry, Chicago, 44 (1040): 421-438.

[111]Hebb, "D.O. Hebb," p. 294-295.

[112]Hebb and W. R. Thompson, "The Social Significance of Animal Studies," in Gardner Lindzey, ed., Handbook of Social Psychology, vol. 2, (Cambridge, Mass.: Addison-Wesley, 1968), 532-561.

[113]Hebb, "D.O. Hebb," p. 295.

[114]Ibid., p. 296.


[116]Ibid., p. 299.

[117]Hebb, The Organization of Behavior (New York:  Wiley, 1949).

[118]Hebb, Textbook of Psychology (Philadelphia: Saunders, 3rd ed., 1972), p. 67.


[120]William James, Principles of Psychology (New York: Holt, 1890), vol. 1, pp. 224-290.