I. HISTORY OF BEHAVIORAL PSYCHOLOGY

The earliest human communities undoubtedly appreciated the systematic application of rewards and punishments as an effective means to control behavior. The domestication of animals throughout prehistory, and the numerous early historical references to the proficiency of animal trainers, further establish a form of behavioral psychology as the most venerable of the folk psychologies. Thus, if the term behavioral psychology is taken to mean only a set of techniques useful for the prediction and control of behavior, then its history is coeval with human history.

As it is generally understood, however, behavioral psychology is not merely a collection of methods for controlling behavior. It also represents a judgment on the nature of psychology itself—a position informed by identifiable traditions within philosophy and the philosophy of science, as well as by the larger scientific context within which psychology seeks a proper place.

Understood in this light, the subject has its origins in the first great age of modern science, the seventeenth century— the century of Francis Bacon, Johannes Kepler, Galileo, Thomas Hobbes, René Descartes, and Isaac Newton, to mention only some of the more celebrated figures. Setting aside the many and fundamental conceptual and scientific disagreements of this era, a coherent theme exists; namely, that an unprejudiced and objective inquiry into the operations of the natural world will yield lawful and useful knowledge. The older world of logical analysis, occult powers, hidden forces, revealed truths, and scriptural authority was now to be replaced by the more modest—but more solid—discoveries of direct experience. The knowable cosmos, from this perspective, is just the observable cosmos.

The two divisions of science most fully developed in the seventeenth century were mechanics and optics, and both of these served as models and metaphors for phenomena only poorly understood. The well-ordered Hobbesian state, the clockwork precision of the Newtonian heavens, and Descartes's stimulus-response psychology are all based upon the metaphor of the machine, as well as on the conviction that fuller explanations in these areas will be drawn from the science of mechanics. Descartes's (1596–1650) psychology of animal behavior, which he extended to include those aspects of human psychology not dependent upon language and abstract thought, is entirely mechanistic and behavioristic, even in the more modern senses of these terms. His explanations for all animal, and most human, behavior were grounded in what would now be called instinctual reflex mechanisms and acquired (but still reflexive) habits. The nervous system, in this view, is an elaborate input-output system organized in such a way that specific patterns of stimulation lead to organized and adaptive patterns of behavior. The tendency to focus on Descartes's famous dualistic solution to the mind–body problem, and his emphasis on the cognitive, rational, and linguistic uniqueness of human beings should not obscure the essentially behavioristic content of his overall psychology.

Criticized in Descartes's own time by Thomas Hobbes and Pierre Gassendi, among others, Cartesian psychology was stripped of its introspective features in the eighteenth century, where it survived within progressive circles as a primitive biological psychology. In British philosophy, David Hartley (1705–1757) stands out in the movement to adapt Newtonian and Cartesian mechanistic principles to the needs of an emerging mental science. His Observations on Man (1749) provides a richly argued and illustrated defense of a behavioristic psychology grounded in (Humean) associationistic principles operating within the sort of reflex framework advocated by Descartes. In France, Julien de La Mettrie's L'Homme-machine (1748) presented an uncompromisingly materialistic psychology, at once antispiritual, reductionistic, and behavioristic. The circle of French philosophes included stridently mechanistic theorists (e.g., Paul-Henri Dietrich, Baron d'Holbach), but also those with a radically environmentalistic orientation (e.g., Claude-Adrien Helvétius), who insisted that social and familial pressures were totally responsible for human psychological development.

As the philosophes and natural philosophers of the eighteenth century were assembling strong rhetorical arguments on behalf of a fully naturalistic psychology, the medical and scientific communities were broadening and deepening its empirical foundations. Robert Whytt's (1714–1766) pioneering studies of spinal reflexes are illustrative. These were accomplished while La Mettrie was offering little more than polemical defenses of psychological materialism. Whytt's research exemplified the steady, modest, and entirely experimental approach of scientists loyal to what they took to be the methods of Newton and Bacon. Early in the nineteenth century, programmatic research of this sort had unearthed the distinct sensory and motor functions of the spinal cord (the Bell-Magendie Law) and had put the mechanistic-behavioristic perspective on firm anatomical foundations. By the 1830s, Marshall Hall (1790–1857), in a tradition of Scottish medical science that includes Whytt and Charles Bell, would put the concept of "reflex function" at the very center of a nascent biological psychology that would influence the ultimate character of modern behaviorism.

It should be noted that it was during this same period (1750–1850) that the so-called animal model became accepted, and, in the early decades of the nineteenth century, a single laboratory might perform vivisection on thousands of animals, none of them anesthetized. Cartesianism, in still another sense, was the gray eminence here, fortifying the scientific community in the belief that nonhuman animals were merely a species of machinery. This perspective, shorn of its horrific surgical practices, would survive in the confident antimentalism of twentieth-century behaviorism.

By the middle of the eighteenth century, the medical clinic was also yielding an ever more coherent account of the causal efficacy of the nervous system in human sensory and behavioral functions. By the end of the century, and as a result of his own original and exhaustive studies (including postmortem examinations of exceptional as well as feeble and felonious persons) Franz Joseph Gall (1758–1828) would offer the "science" of phrenology as a developed and systematic psychology—a psychology grounded in the principle that all sensory, motor, affective, and cognitive functions are brought about by conditions in the brain and its numerous subsystems. Once again, the evidence all pointed to a quasi-mechanistic system, both complex and lawgoverned, functioning in such a manner as to adjust (or fail to adjust) behavior to the demands of the environment.

The Evolutionary Perspective

By the time Charles Darwin published On the Origin of Species (1859), the "Darwinian" perspective was already dominant in scientific and progressive circles. Adam Smith's The Wealth of Nations (1776), Jacques Turgot and his party of "physiocrats, " and the writings of any number of philosophes point to a (more or less) settled Enlightenment position: The free movement of ideas, goods, and persons— constrained by no more than "natural" forces—produces an ever more refined, successful, and robust stock.

But Darwin's monumental contribution went beyond this general perspective and reached the level of a developed and richly integrative theory. Its implications for psychology were clear: As there is no sharp line dividing places along the broad evolutionary continuum that humanity shares with the balance of the animal economy, there is no reason to confine inquiries into complex psychological functions to the study of human beings.

Antecedents in Psychology

Darwin's evolutionary theory emphasized differences in degree, not in essence. Thus, the most complex human psychological attributes could, in principle, be examined in a more systematic fashion by studying their simpler, but kindred, manifestations in nonhuman animals. Studies of this sort, it was assumed, would establish psychology's own independent scientific status. As Herbert Spencer (1820–1903) declared:

The claims of Psychology to rank as a distinct science … are not smaller but greater than those of any other science. If its phenomena are contemplated objectively, merely as nervo-muscular adjustments by which the higher organisms from moment to moment adapt their actions to environing coexistences and sequences, its degree of specialty, even then, entitles it to a separate place. (Principles of Psychology, p. 141)

In the patrimony of Darwin, and influenced chiefly by his Descent of Man (1871), specialists in animal psychology appeared before the end of the nineteenth century and made their own contributions toward a behavioral science. For all his anthropomorphic tendencies, George Romanes (1848–1894), in his Animal Intelligence (1882) and Mental Evolution in Animals (1883), put the study of animal behavior on the map of the new psychology. All that was needed to prepare this Darwinian psychology for adoption by the forthcoming generations of behaviorists was to strip it of just this anthropomorphism. C. Lloyd Morgan, in his Introduction to Comparative Psychology (1894), delivered his famous canon:

In no case may we interpret an action as the outcome of the exercise of a higher psychic faculty, if it can be interpreted as the outcome of the exercise of one which stands lower in the psychological scale. (p. 53)

Thus, with this insistence on explanatory parsimony, did the "ism" in behaviorism begin to take shape.

It is customary, if misleading, to date the birth of experimental psychology with Wilhelm Wundt's founding of the discipline's first university laboratory at Leipzig in 1878–1879. Wundt (1832–1920) was perhaps the discipline's most prolific writer. His texts, which were wideranging and immensely influential at the time psychology departments were being formed in Europe, England, and the United States, emphasized experimental over ethological (naturalistic) modes of inquiry. But the reading of Wundt was rather selective. In his less-consulted multivolume Völkerpsychologie (best rendered as "anthropological psychology") he developed and defended the nonexperimental and essentially historical anthropological mission of psychology, drawing attention to the limits of reductionistic strategies and explanations. Even with this broadened perspective, Wundt remained loyal to the scientific views of his age, acquired in his medical education and as he assisted the great Hermann von Helmholtz. In these respects he was representative of an entire generation of thinkers committed to the scientific study of psychology and the abandonment of purely philosophical modes of analysis, wherever the scientific and experimental alternative was practicable.

In the Wundtian tradition, however, the subjects of scientific inquiry were taken to be mental processes and functions—those now generally dubbed cognitive. Moreover, although he did much to advance comparative psychology in his textbooks, the bulk of his theoretical writings, and all of the research undertaken in the Leipzig laboratory, focused on human psychology and the development of a science of mental life. To this extent, Wundtian psychology formed a path distinct from that so heavily trod by the neurophysiologists, anatomists, and clinicians, a path more readily associated with the introspective philosophical psychologists (e.g., John Locke and David Hume). Nor was it clear that Wundtian psychology had a place within the larger naturalistic context of Darwinian science.

Labels offer useful shortcuts, but they can be misleading. It may be said, with ample qualifications, that the Wundtian perspective, at least in the hands of his most influential students (e.g., Edward B. Titchener), was structuralist. Any number of passages and entire chapters in books by Wundt are devoted to the (hypothetical) constituents or components of thought. And, if structuralism (according to which the task facing a scientific psychology requires an analysis of the structure of consciousness) and functionalism (which focuses instead on the functions served by the behavior of animals or the functions of the nervous system itself) are to be understood in essentially dialectical terms, it is also the case that Wundt's major works are not beholden to the idiom of functionalism. But his attention to the workings of the nervous system, his attempts to provide a loosely evolutionary framework for both human and animal psychology, and his problem-centered cognitive psychology are all anticipations of the functionalist psychology so explicit in the works of William James (1842–1910).

What is relevant here in the tension (real or apparent) between structuralism and functionalism in the history of modern psychology is the claim later made by John B. Watson (1878–1958) that behaviorism was to replace both. In significant respects, it may be said to have replaced both by merging the two rather than by fully rejecting either. Structuralism, which was never a central feature of Wundt's own agenda for the discipline, has this much in common with behaviorism: It is a reductionistic theory or strategy, according to which complex and psychologically significant ensembles can be analyzed into more elementary components. Further, both posit that the only valid evidence is the observable and repeatable evidence gleaned by laboratory investigations. For all their differences, then, behaviorism and structuralism, in their mechanistic and reductive commitments, were faithful to that "religion of science" launched in the seventeenth century.

Functionalism, of course, is the immediate precursor to behaviorism and even a version of it, depending on how the term is to be understood. One account of it is defended by Alexander Bain (1818–1903), the founder of the journal Mind and intimate friend of John Stuart Mill. In The Senses and the Intellect (1855) and The Emotions and the Will (1859), Bain argued that the discipline of psychology was to be advanced by merging its issues and findings with the science of physiology in such a way as to ground psychological processes in the functions of the nervous system. Functionalism, in this sense, is a function-based psychology whose general laws are derived from neurophysiology. From still another (but quite compatible) perspective, such as that defended by William James, the question to ask of any psychological process or phenomenon is what function it serves in the larger context of the organism's (person's) overall and long-term interests. The psychological event is explained when the functions it serves are delineated. These, in the most general sense, are adaptive functions, rendering the organism more successful in its transactions with the environment. In the writings of William James, this orientation is tied to a pragmatism that anticipates the central tenets of modern behaviorism.

Modern Behavioral Psychology

The Nobel Prize–winning research of Ivan Pavlov (1849–1936) addressed gastric physiology and the chemistry of digestion. But in the process of studying the formation and secretion of digestive enzymes, Pavlov discovered that initially automatic or innate reflex mechanisms could be controlled externally by associating them with specific events in the environment. His theories of classical conditioning were grounded in neurophysiology and were intended to replace the mentalistic approach of traditional psychology. In this aim he was joined by the American psychologist John B. Watson, widely regarded as the father of behaviorism.

In his influential essay "Psychology as the Behaviorist Views It" (1913), and in his widely read and cited Psychology from the Standpoint of a Behaviorist (1919), Watson waged relentless war on introspective psychology, structuralism, "folk" psychology, and the entire tradition of philosophical speculation regarding the nature of human nature. He insisted that the only proper subject matter of any science is directly observable events, which for psychology means observable behavior. In tying his recommendations to a version of the Pavlovian theory, Watson failed to produce the sort of behavioral psychology compatible with the functionalistic and pragmatic bent already dominant in America. But his writing did much to put mentalistic psychologies on notice and promote a seemingly objective, scientific, and descriptive discipline, practical in its aims and stridently antimetaphysical.

This much of the Watsonian legacy was accepted by the most influential figure in the history of behavioral psychology, B. F. Skinner (1904–1991). In numerous books and articles, in scores of laboratory demonstrations, and through a veritable legion of students and coworkers, B. F. Skinner dominated psychology in the United States and, indeed, much of psychology around the world, for a quarter of a century. From 1950 until the 1970s, specialists in a wide variety of psychological employments came to regard themselves as "behavioral scientists, " adopting the idiom and perspective of "Skinnerian" psychology and fashioning methods and measurements akin to those of the "Skinner box" and the cumulative recorder.

As early as 1938, in The Behavior of Organisms, Skinner had argued for the independence of behavioral science from physiology or other (even if somehow related) sciences. The facts of observed behavior, he insisted, remain what they are, no matter what the nervous system is found to be doing, no matter what the genetic composition of the organism proves to be, and no matter what theory is invented or adopted to account for these facts. Taking his lead from the research of Edward L. Thorndike (1874–1949), Skinner devoted himself to the study of operant, or instrumental, behavior—the behavior that is instrumental in securing positive reinforcers or in avoiding aversive stimulation. Unlike Pavlovian reflexes (or respondents, in Skinner's terminology), operant behaviors actually operate on and alter the animal's environment. Behavior that results in positive reinforcement (food, for example) becomes statistically more probable. Nonreinforced behavior—behavior that has no systematic effect on the environment—simply drops out. Thus, behavior within an environment containing reinforcing contingencies is not unlike the evolutionary arena itself. Those behaviors that result in more successful adaptations survive, while those that do not are extinguished.

As developed by Skinner, behavioral psychology is a descriptive, empirical science—more akin to engineering, perhaps, than to physics—and is able to identify the conditions under which behavior is rendered more or less probable. Useless to this enterprise are theories laden with hypothetical processes, hidden variables, or private "states." Perhaps the most concise philosophical defense of the perspective was provided by Gilbert Ryle in The Concept of Mind (1949), in which the Cartesian "ghost in the machine" was analytically exorcised, leaving in its wake a collection of psychological attributes uniquely specified by observable behavioral events and dispositions.

Skinner's version of behavioral psychology, though the most influential, is but one of several developed in the twentieth century. The main points of division among various schools or types are three: (1) the level of explanation to be attained by a behavioral psychology; (2) the room within such a psychology for nonobservable (mental) events and processes; (3) the proper place of such a psychology within the larger context of the natural (biological) sciences. On each of these points, major and self-proclaimed behaviorists have taken positions at variance with Skinner's.

Clark Hull (1884–1952), for example, adopted the nomological-deductive model of scientific explanation. According to the dominant version of the model, an event is explained when it is shown to be deducible from a general law, not unlike explanations in classical physics. He attempted to develop a formal theory of behavior based on a number of hypothetical constructs (e.g., "habit-strength") and intervening variables (e.g., fatigue-substances generated by muscular activity). Hullian behavioral psychology is characterized by pages of mathematical equations expressing such relationships as that between learning and practice, between strength of response and magnitude of reward, or between speed of response and hours of food-deprivation.

E. C. Tolman (1886–1959) defended a form of cognitive -behavioral psychology that grounded explanations of problem solving on the part of nonhuman animals in such notions as "cognitive maps." Rats, for example, who learn the various turns in a maze and are later placed on top of the maze box will run directly toward the goal rather than retracing the successful learned paths. What the rats have, in Tolman's theory, is a map or representation of the situation, and very different patterns of behavior can be arranged to achieve the same results.

Yet other behavioristic psychologists, notably Karl Lashley (1890–1958), retained their commitment to the study of observable behavior, while insisting that a science of behavior had to be fully integrated into the brain sciences, and had to make contact with the well-established cognitive dimensions of human and animal psychology. In this, the influences and criticisms of such Gestalt psychologists as Wolfgang Köhler (1887–1967) wrought changes on the behavioristic outlook—or otherwise rendered the outlook itself dubious.

Ethical Implications

From the first, the Darwinian, reductionistic, and positivistic character of behaviorism targeted it for criticism from expected (humanistic) quarters. Yet, unlike the value-neutral orientation of much of modern science, behaviorists have tended to defend their perspective on ethical grounds. Both Watson and Skinner were explicit in this regard. Skinner's Beyond Freedom and Dignity (1971), though dismissive of traditional moral theories and their supporting "folk" psychologies, contended nonetheless that a behaviorally engineered society would achieve the most precious of the ends envisaged by ethical theorists. His work inspired the formation of several small communities organized around principles of operant conditioning, with desired behavior brought about without the moral tags of "praise" and "blame." His work also provided the theoretical and technical foundations for various "behavior therapies" applied to disturbances ranging from bed-wetting to catatonic withdrawal. Considered ethically, these methods would seem to be neither more nor less coercive than those arising within other theoretical contexts and employed for the benefit of consenting patients.

In viewing human nature as part of nature at large, and as impelled by the same evolutionary pressures faced by the balance of the animal kingdom, behavioral psychology is neither more nor less humanistic than, say, psychoanalytic theory or, for that matter, the contemporary neurocognitive psychologies that have all but replaced behaviorism. Skinner rejected moral theories grounded in deontological or transcendental arguments, but accepted the proposition that complex societies require the imposition of constraints, and that coercive principles and practices must be justified in ways conducive to a flourishing and productive life within such societies.

It was clear by the end of the twentieth century that the central precepts and methodology of behaviorism would be steadily overtaken and replaced by what is generally referred to as cognitive neuroscience. Though the term is new, the perspective is not, for it has been the guiding perspective within physiological psychology at least since early in the nineteenth century. Rejected is the claim that the chief sources of behavioral control are external to the organism. Rather, what is assumed is the evolution of the nervous system as "pre-wired" (though not necessarily "hard-wired"); that is, it is able to perceive the environment selectively, to code or represent it in quasi-computational ways, and to do so by way of distinguishable "modular" processes in the brain.

If cognitive neuroscience has overtaken behaviorism within the theoretical and experimental domains, the complexities of mental and social life have rendered it suspect in the wider realms of thought and action. Life, as depicted by Watson and Skinner and otherwise implicit in the very language of behavioral psychology, matches up poorly with the life actually lived by most human beings and many other species. In ignoring or depreciating the richly social, self-moving, and self-conscious dimensions of life—and thus the irreducibly moral terms that rational beings must invoke to live together in a principled way—the architects and defenders of radical versions of behavioral psychology have more or less resigned from the domain of ethical discourse.

daniel n. robinson (1995)

revised by author

BIBLIOGRAPHY

Hartley, David. 1998 (1749). Observations on Man. Washington, D.C.: Woodstock Books.

Morgan, C. Lloyd. 1978 (1893). Introduction to Comparative Psychology: The Limits of Animal Intelligence. Significant Contributions to the History of Psychology, Series 2, ed. Daniel N. Robinson. Westport, CT: Greenwood Press.

Robinson, Daniel N. 1986. An Intellectual History of Psychology. Madison: University of Wisconsin Press.

Robinson, Daniel N. 1998. The Mind: An Oxford Reader. Oxford: Oxford University Press.

Ryle, Gilbert. 1949. The Concept of Mind. London: Hutchinson.

Skinner, B. F. 1938. The Behavior of Organisms: An Experimental Analysis. New York: Appleton Century.

Skinner, B. F. 1971. Beyond Freedom and Dignity. New York: Knopf.

Spencer, Herbert. 1896. The Principles of Psychology, 3rd edition. New York: Appleton.

Tolman, Edward C. 1948. "Cognitive Maps in Rats and Man." Psychological Review 55(4): 189–208.

Watson, John B. 1919. Psychology from the Standpoint of a Behaviorist. Philadelphia: Lippincott.