Figure 1.1 Descartes' model of how an external event might cause bodily movement.
We are all very interested in what other people do, and we also want to know why people act as they do. While "common-sense explanations" about these issues are plentiful, we shall be concerned here with scientific answers to the questions raised. In the last hundred years or so, many areas of human life have been transformed by scientific and technological developments. In this first chapter, we will briefly review historical progress towards a scientific account of human behavior and a possible technology for changing human behavior.
It is never possible to identify precisely the moment at which interest in a particular subject began, but we do know that by 325 B.C., in ancient Greece, Aristotle had combined observation and interpretation into a naturalistic, if primitive, account of behavior. Aristotle sought to understand the causes of body movements, and of the discriminations made by humans and other animals. He described many categories of behavior, such as sense perception, sight, smell, hearing, common sense, simple and complex thinking, appetite, memory, sleep, and dreaming. His topics sound familiar to us today, as they are still to be found in some form or other in nearly every comprehensive text of psychology. Aristotle was less interested in the prediction of events than we are today, and consequently his explanations of behavior have a less modern flavor. Aristotle was concerned with explaining the various activities of an individual by showing them to be specific instances of general "qualities", such as appetite, passion, reason, will, and sense-ability (Toulmin and Goodfield, 1962).
The observations and classifications of Aristotle and the Greek investigators who followed him represented a substantial beginning in a naturalistic attempt to understand the causes of human and animal behavior. However, the new science declined with the demise of Hellenic civilization. In the western world, the early Christian era and the Middle Ages produced an intellectual climate poorly suited to observation and investigation: attention was turned to metaphysical matters. The Church Fathers began, and the mediaeval theologians completed, a conceptual transformation of Aristotle's purely abstract "quality" of mind into a supernatural entity named the soul. In their conceptual framework the causation of human behavior was entirely attributed to the soul, but the soul was regarded as non-material, in-substantial and super-natural.
This dualistic (or two-system) doctrine stated that there was no direct connection between soul and body, and that each inhabited a separate realm. By locating the causes of behavior in the unobservable realm of the spirit or soul, dualism inhibited a naturalistic study of behavior, and for a very long time no interest was taken in an empirical or observational approach to behavior. We have to jump forward to the seventeenth century, the time of Galileo and the rise of modern physics, to pick up the threads that were eventually to be rewoven into a scientific fabric.
The work of René Descartes (1596–1650), the French philosopher and mathematician, represents a critical point in the development of a science of behavior. Although Descartes produced one of the clearest statements of the dualistic position, he also advanced behavioral science by suggesting that bodily movement might be the result of mechanical, rather than supernatural, causes.
Descartes was familiar with the mechanical figures in the French royal gardens at Versailles that could move and produce sounds, and observations of these probably prompted him to put forward a mechanical account of behavior. The machines in the royal gardens worked on mechanical principles. Water was pumped through concealed tubes to inflate the limbs of the figures, producing movement, or was conducted through devices that emitted words or music as the water flowed by. Descartes imagined that animals and human beings might be a kind of complex machine, perhaps constructed in a similar way. He substituted animal spirits, a sort of intangible, invisible, elastic substance, for the water of the Royal Figures and supposed the spirits to flow in the nerves in such a way as to enter the muscles, thereby causing them to expand and contract, and in turn make the limbs move.
Some of the Royal Figures were so arranged that if passers-by happened to tread on hidden tiles, hydraulic mechanisms caused the figures to approach or withdraw. Descartes took this mechanical responsiveness as a model for explaining how an external environmental stimulus might cause a bodily movement. An illustration in one of his works (see Figure 1.1) shows a withdrawal of a human limb from a flame. According to Descartes, the "machine of our body is so formed that the heat of the flame excites a nerve which conducts that excitation to the brain. From the brain, animal spirits are then passed out, or reflected back via that nerve to the limb, enlarging the muscle, and so causing a contraction and withdrawal" (Fearing, 1930).
Figure 1.1 Descartes' model of how an external event might cause bodily movement.
Descartes' willingness to view human behavior as determined by natural forces was only partial. He confined his mechanical hypotheses to certain "involuntary" activities and supposed the rest to be governed by the soul, located in the brain. The soul guided even the mechanisms of the "involuntary" activities, much in the way an engineer might have directed the workings of the Royal Figures.
In spite of this dualism, and in spite of his choice of a hydraulic principle, Descartes' formulation represented an advance over earlier thinking about behavior. The theory of the body as a specific kind of machine was one that was testable by observation and experiment. This property of "testability" was conspicuously lacking in the mediaeval explanations that preceded Descartes, in re-establishing the idea that at least some of the causes of animal and human behavior might be found in the observable environment, Descartes laid the philosophical foundations that would eventually lead to an experimental approach to behavior.
Descartes' views symbolize the new interest in mechanism that was to lead to experimentation on "reflected" animal action. However, a century elapsed before a Scottish physiologist, Robert Whytt, experimentally rediscovered and extended Descartes' principle of the stimulus in 1750. By observing systematic contraction of the pupil of the eye to light, salivation to irritants, and various other reflexes, Whytt was able to state a necessary relationship between two separate events: an external stimulus (for example, a light) and a bodily response (for example, a pupil contraction). Moreover, Whytt's demonstration that a number of reflexes could be elicited in the frog, even when the brain had been disconnected from the spinal cord, weakened the attractiveness of the soul as an explanation of all behavior. Yet an eighteenth-century thinker was not quite able to regard the stimulus alone as a sufficient cause of behavior in an intact, living organism. The soul, thought Whytt, probably diffused itself throughout the spinal cord and the brain thereby retaining master control of reflexes.
Figure 1.2 A simple reflex and its connections to the spinal cord.
In the following 150 years, more and more reflex relationships were discovered and elaborated, and the concept of the stimulus grew more useful in explaining animal behavior. At the same time, nerve action became understood as an electrical system and the older hydraulic or mechanical models were discarded. By the end of the nineteenth century, spiritual direction had become superfluous for "involuntary action", and Sir Charles Sherrington, the celebrated English physiologist, could summarize the principles of reflex behavior in quantitative stimulus-response laws. These laws relate the speed, magnitude, and probability of the reflex response to the intensity, frequency, and other measurable properties of the stimulus. The anatomy of an example of the simplest type of reflex, consisting of two nerve cells or neurons, is shown in Figure 1.2, One neuron (the afferent neuron) transmits neural impulses resulting from the stimulus to the spinal cord and the other (the efferent neuron) runs from the spinal cord back to the muscle. Firing of the efferent neuron results in a motor response of the muscle.
By 1900, there could be no doubt that reflexive behavior was a suitable subject for scientific analysis and that analysis was well advanced. However, reflexes clearly accounted for only a small proportion of the behavior of human beings and so-cailed "higher animals", and it had yet to be established that the remainder of behavior could be subjected to the same sort of analysis.
Just before the beginning of the twentieth century, Ivan Pavlov, the Russian physiologist, was carrying out experiments on the digestive secretions of dogs. He noticed that while the introduction of food or acid into the mouth resulted in a flow of saliva, the mere appearance of the experimenter bringing food would also elicit a similar flow. Pavlov was by no means the first person to make observations of this sort; but he seems to have been the first to suspect that their detailed study might provide a clue to the understanding of how animal behavior is able to adapt to circumstances. It was this insight that led him to a systematic study of these reflexes, which he called conditional reflexes, because they depended, or were conditional, upon some previous events in the life of the animal. The appearance of the experimenter had not originally elicited saliva. It was only after his appearance had frequently occurred along with food or acid that it had this effect. Pavlov's unique contribution was to show experimentally how conditioned reflexes (an early translation from the Russian rendered "conditional" as "conditioned", and this has become the normal expression) came to be acquired, how they could be removed (extinguished), and what range of stimuli was effective in their production. In time, Pavlov was to lay down a general law of conditioning: after repeated presentation of two stimuli at overlapping times, the one that occurs first comes eventually to elicit (that is, produce automatically) the response that is normally elicited by the second stimulus. A modified version of this law, or principle, is with us today.
Pavlov stated how the explanation of behavior should proceed:
The naturalist must consider only one thing: what is the relation of this or that external reaction of the animal to the phenomena of the external world? This response may be extremely complicated in comparison with the reaction of any inanimate object, but the principle involved remains the same. Strictly speaking, natural science is under obligation to determine only the precise connection which exists between a given natural phenomenon and the response of the living organism to that phenomenon... (Pavlov, 1928, p. 82).
Very often major advances in a field are the result of, or are accompanied by, methodological innovations. This is certainly true in the case of Pavlov and conditioned reflexes. Pavlov discovered that controlled environmental conditions were essential for successful behavioral experimentation. His dogs had to be kept in steady temperatures and in sound-proof chambers for the experiments, during which stimuli were presented in a controlled fashion and responses recorded in ways which did not interfere too much with the experimental participant. He also realized that only dogs in good general health made satisfactory participants in experiments. An illustration of the typical experimental arrangements, as used at the end of the nineteenth century, by Pavlov and his colleagues at the Institute of Experimental Medicine in Saint Petersburg appears in Figure 1.3.
The apparatus used is well described in the following passage:
Figure 1.3 A typical arrangement for studying salivation in a conditioning experiment in Pavlov's 19th century laboratory.
First, a normal dog is familiarized with the experimental situation until he shows no disturbance when placed in harness and left alone in a room especially designed to cut off unwanted outside stimuli. A small opening or fistula is made in the dog's cheek near the duct of one of the salivary glands. When the fistula is healed, a glass funnel is carefully cemented to the outside of the cheek so that it will draw off the saliva whenever the gland is activated. From the funnel, the saliva then flows into a glass container or fails, drop by drop, upon a lightly balanced recording platform. The magnitude of responses to various stimuli can be measured by the total volume or the number of drops secreted in a given unit of time. The experimenter, who sits in an adjoining room, can make his measurements, apply what stimuli he desires (including food), and observe the dog's behavior through a window. (Keller and Schoenfeld, 1950, pp. 16–17)
The experimenter is thus in a position to measure the salivary reflex precisely. He or she is also able to control carefully the presentations of various stimulus events to the organism.
We will examine in detail an experiment by one of Pavlov's students (Anrep, 1920), as an example of the Pavlovian method and results. In this experiment by Anrep (1920), a tone was sounded in the animal's room for 5 seconds. Then, 2 or 3 seconds later, a piece of food was given to the dog. This pairing of tone with food presentation was repeated after intervals ranging from 5 to 35 minutes. In order to observe the effect of the tone alone, the experimenter occasionally presented it for 30 seconds, unpaired with food. Over the course of 16 days, 50 tone-food presentations and 6 tone-alone tests were made. The principal data of Anrep's experiment were obtained during the 6 tone-alone tests. During these tests, he carefully measured both the total number of drops of saliva and the time (or latency) between the onset of the 30-second test tone and the first drop of saliva. He found that, after one tone-food pairing, presentation of the tone alone produced no salivation at all. After 10 such pairings, however, 6 drops appeared in the tone-alone test, and the first of these 6 drops came 18 seconds after the onset of the test tone. After 20 such pairings, 20 drops were produced, the first drop coming now at only 9 seconds. From 30 pairings onward, approximately 60 drops of saliva were obtained during each test, and they began to appear in the first second or two after the onset of the test tone. The results of the experiment are clear-cut: salivation occurs reliably to an arbitrarily-selected stimulus, an auditory tone, after the tone is paired with food 30 times.
Pavlov's realization that he was investigating phenomena that might be of general significance, his development of sound experimental techniques, and, above all, his careful collection of a body of systematically related experimental findings over a period of more than thirty years, mean that he was a great scientist. We now call the conditioning process he investigated classical conditioning, because it was the type of conditioning that was investigated earliest, and research has continued over the one hundred years since his original studies.
In the terminology we shall use here, if a conditioned stimulus (CS) –such as the ringing of a bell in one of Pavlov's experiments – is reliably followed by an unconditioned stimulus (US) – such as food in the mouth –on a number of occasions, then the CS comes to elicit (or automatically produce) a conditioned response. Pavlov demonstrated this process many times, and gradually varied features of his experiments to establish the generality of the effect. He also showed that there were a number of related phenomena concerned with extinction and discrimination, and we will discuss some of these in later chapters.
Pavlov, believed, and later investigators demonstrated, that he was investigating a process that enabled many species – not just dogs – to adapt to many aspects of their environments. He is thus credited with discovering the first "general learning process". It is general because it can affect many response systems, can involve many types of stimuli, and is seen in many animal species. We will see later that it is importantly involved in human behavior and the alleviation of human behavioral problems.
Pavlov's work showed how "new" reflexes could be acquired to supplement those "built-in" reflexes that the organism possesses prior to any appreciable experience of the world. As such, it represents the culmination of Descartes' mechanistic view of reflex behavior. However, it appeared that only those responses that form part of an existing reflex (such as the salivation produced by the stimulus, dry-food-in-the-mouth) can become conditioned reflexes, and thus much non-reflexive behavior still remained to be scientifically analyzed. This behavior comes into the category traditionally described as voluntary, or under the control of the will, and it is just this category that Descartes assigned to the control of an unobservable soul. Descartes' maneuver only postponed a scientific inquiry, however, because we are now faced with the difficult problem of describing the relations between the soul which we cannot observe, and the patterns of behavior, which we do observe.
The view that voluntary human behavior was not a suitable subject for a scientific study came under attack in 1859. In that year, Charles Darwin proposed his theory of evolution, holding that human beings are members of the animal kingdom, and that differences between humans and other animals are quantitative and matters of degree. As a distinguished historian of psychology put it:
The theory of evolution raised the problem of animal psychology because it demands continuity between different animal forms and between man and the animals. In a vague way the Cartesian [Descartes'] notion still prevailed. Man possessed a soul and the animals were believed to be soulless; and there was, moreover, little distinction then made between a soul and a mind. Opposition to the theory of evolution was based primarily upon its assumption of continuity between man and the brutes, and the obvious reply to criticism was to demonstrate the continuity. The exhibition of mind in animals and of the continuity between the animal and the human mind thus became crucial to the life of the new theory (Boring, 1929, pp. 462–463).
Darwin's theory derived support from the many careful observations that he had made of fossils and the structure of flora and fauna living in isolated areas of the earth. In addition, he had investigated the behavior by which animals adapted to their environments. Darwin's behavioral observations were so comprehensive and detailed as to mark the first systematic attempt at a comparative animal psychology (see Darwin, 1873).
Darwin's interest in behavior was, as Boring noted, based on what it could reveal about mind. Thus, the demonstration of complexity and variety in adaptive behavior of animals in relation to their changing environments seemed to prove that they, like human beings, must also think, have ideas, and feel desires. Eventually, Darwin was to be criticized for his anthropomorphism; that is, for trying to explain animal behavior in terms of mentalistic concepts generally used to account for human behavior. But few thought at the time to raise the far more radical methodological question: Do traditional mentalistic concepts (thoughts, ideas, desires) have explanatory value even for human behavior?
Darwin's friend, George John Romanes, an English writer and popularizer of science, wrote a book on animal intelligence (Romanes, 1886) in which he compared the behavior of various species of animals. Romanes gathered material from careful observation of animals, but he also took evidence from popular accounts of pets and circus animals. For this reason, his method has come to be called anecdotal. The anthropomorphic and anecdotal methods of Darwin and Romanes, respectively, marked the renewal of interest in adaptive animal behavior and its relationship to human behavior, and therefore represent important historical precursors of a truly scientific and experimental analysis of behavior. The crucial conceptual change had occurred: animal and human behavior was now approached from a scientific point of view and in a biological context.
In 1898, Edward L. Thorndike, of Columbia University in the USA, published the results of a number of laboratory studies of "problem solving behavior" in kittens, dogs, and chicks. His methods departed radically from those of the casual observers who had preceded him. The behavior studied was escape from a confining enclosure, and the acts, such as pulling a string, moving a latch, pressing a lever, or prying open a lock, were chosen for their convenience and reliability of observation. A sketch of his apparatus is shown in Figure 1.4. Since any of these responses could be arranged to be instrumental in producing escape from the box, Thorndike classed them as instrumental behavior. A common feature of all his experiments was that, as a result of experience in the experiment, the behavior of each animal participant was systematically changed.
Four aspects of Thorndike's work on instrumental behavior gave it a modern quality not seen in earlier investigations:
Figure 1.4 Thorndike's puzzle box for studying instrumental or operant behavior in animals. Escape from the box could be made contingent upon one of a number of responses.
From his work with animals in puzzle boxes, Thorndike derived a number of principles or general laws of behavior which he believed held for many species and for many kinds of behavior. One of these, in a somewhat modified form, has come down to us today. Thorndike noticed that when animals were first put into the puzzle box, they made many diffuse struggling responses. Eventually, one of these responses would happen to operate the escape mechanism and the door would open, permitting the animal to escape from the box and to obtain a small quantity of food. Thorndike observed that the behavior which first let the animal out was only one of many that the animal made in the situation. Yet, as the animal was repeatedly exposed to the situation, it came to make fewer and fewer superfluous responses. Eventually, it made practically none apart from the successful responses.
Thorndike concluded from his experimental findings that the successful past results or effects of behavior must be an important influence in determining the animal's present behavioral tendencies. Consequently, Thorndike called this ability of the past effects of behavior to modify the behavior patterns of the animal the law of effect. It survives today as a fundamental principle in the analysis of adaptive behavior. In brief modern form, the law of effect states that if a response is reliably followed by an important consequence (such as food for a hungry organism), that response will become more frequent.
The importance of Thorndike's formulation of the law of effect for the development of behavioral analysis lies in its generality. Unlike Pavlov's laws of the conditioned reflex, the law of effect was readily applied to those responses usually regarded as voluntary. Indeed, it is more applicable to that type of behavior than to reflexive behavior, which is relatively insensitive to its consequences or effects.
Thorndike initiated the laboratory study of behavior which is adaptive; that is, behavior which enables an organism to adapt or adjust rapidly to the prevailing environmental conditions, and comes into the category often described as "voluntary". In so doing, he discovered the law of effect and this discovery has had a profound influence on the subsequent development of behavioral analysis. However, Thorndike's own interest in behavior arose from his concern as a psychologist with mental processes, which, at the end of the nineteenth century, were seen as the key to understanding psychology.
Although psychology at that time was seen as a science of mental contents, mental processes, and mental acts, it actually involved investigations of behavior. From the results of these investigations, inferences were made about the mental processes that were presumed to be crucially involved. In some of the studies that were carried out at that time, associations of ideas were inferred from the learning of nonsense syllables, or identical sensations were inferred from observations of behavior when a human experimental participant matched two different environmental objects in different contexts (for example, two samples of gray paper under different conditions of illumination), or speed of the mental process was inferred from an individual's reaction time. Given these uses of behavioral procedures, and the influence of Darwin discussed earlier, it was perhaps not surprising that when Thorndike designed his study of problem solving he chose animals to participate in the experiments. If the behavior of human organisms could lead to inferences about mental processes, why not the behavior of animals? Furthermore, as Pavlov's and Thorndike's work revealed, the study of animal behavior may allow specific research questions to be addressed more precisely through the use of carefully controlled experiments.
Despite Thomdike's innovations, the man who did the most to clarify the relationship between behavior and psychology was John B, Watson. The earliest work of this American psychologist was concerned with the sense-modalities that the rat uses in learning to find its way through a maze. As Watson carried on his animal studies, he came to be more and more disturbed by the prevailing view that behavior possessed significance only as it shed light on mental or conscious processes. It occurred to Watson that the data of behavior were valuable in their own right and that the traditional problems of psychology, such as imagery, sensation, feeling, and association of ideas, could all be studied by strictly behavioral methods.
In 1913, Watson published a now classic paper defining psychology as the science of behavior and naming this new psychology "behaviorism". Watson argued in this paper that the study of behavior could achieve an independent status within science. The goal of such a science could be the prediction and control of the behavior of all animals, and no special preference need be given human beings. The behaviorist, claimed Watson, need relate his studies of rats and cats to human behavior no more (nor less) than the zoologist need relate his dissections on frogs and earthworms to human anatomy. By his doctrine, Watson was destroying the "homocentric" (human-centered) theory of human importance in the behavioral world just as much as Copernicus had destroyed the geocentric (earth-centered) theory of the universe, four hundred years earlier. Watson's main theme was that psychology must be objective: that is, it must have a subject matter which, like that of the other sciences, remains independent of the observer. Up until that time, psychology had attempted to take as its subject matter self-observation of mental processes, but this strategy lacks an independent observer located outside of the system being considered. Watson realized that this meant that conflicts about the contents of consciousness could not be resolved, even in principle. There were no grounds for preferring one person's report over another's. This, he argued, made that approach inherently unscientific, but the problem could be resolved if behavior itself was treated as the primary subject matter of psychology. If we take "behavior" to include only those human or animal activities that are, in principle, observable, then any statement about behavior made by one observer or experimenter can be verified by another person repeating the observations.
Watson's program for the new science of behavior was far-reaching and, for its time, remarkably sophisticated. In its insistence on behavior as an independent subject matter of a science aimed at the prediction and control of behavior, and in its stress on a detailed analysis of the environment and behavior into stimuli and responses as the way to eventual understanding of complex patterns of behavior, Watson's program laid the basis for modern viewpoints.
Thorndike's early experiments on animal behavior and Watson's definition of a science of behavior established the potential value of experimental research with animals. However, relatively little had been discovered at that early stage. In Pavlov's principle of conditioned reflexes, Watson thought he saw an explanatory mechanism for the many complex and subtle adjustments that adult organisms, including humans, make to their environments. But the attempt to force all behavior into the reflex mold was to prove a failure, and Watson failed to appreciate the significance of Thorndike's law of effect. Further progress was slow until another American, B.F. Skinner, made a number of innovations.
In a series of papers beginning in 1930, Skinner proposed a formulation of behavior which arose out of observations made on single organisms responding in a carefully controlled and highly standardized artificial experimental situation. Skinner's organism was the white rat, which had also been studied by Watson and others, but his apparatus consisted of an enclosure or box containing a small metal bar, or lever, which, if depressed by the rat, resulted in the delivery of a small pellet of food to a cup located directly under the lever. Atypical version of the apparatus is shown in Figure 1.5. Under these experimental conditions, a hungry rat left alone in the box would soon come to press the lever at a sustained moderate rate until the number of food pellets delivered had begun to satiate the animal. Skinner's experimental situation and his approach to the problems of behavior were unique in many respects. Skinner saw the necessity for making available a sensitive and reliable dependent variable; that is, some quantitative aspect of behavior which could vary over a wide range and enter into consistent and orderly relationships with past and present environmental, or independent, variables. His discovery that the frequency of occurrence of the lever-press response during a given interval of time, the response rate, satisfied these conditions was a major step towards an analysis of how behavior is modified by many aspects of the environment.
Skinner's approach to the study of behavior differed in certain ways from those of both his predecessors and his contemporaries. As a fundamental proposition, he held that a science of behavior could be what he called descriptive or functional; that is, it could limit itself to the discovery of relationships or correlations between measurable variables. He maintained that the identification of such functional relationships between aspects of behavior (the dependent variables) and parameters of the environment (the independent variables) should be the goal of a science of behavior. Skinner also argued that the investigations must be systematic, in that the relationships obtained should be linked by a common thread. By confining his observations to the ways that a single dependent variable (the rate, or frequency in time, of an arbitrary piece of behavior) changed with varied environmental conditions, Skinner kept his own work highly systematic (Skinner, 1938).
Figure 1.5 An experimental chamber, usually called a Skinner box, based on the one originally devised by B.F. Skinner for the study of operant conditioning.
Skinner's methodological contributions to the development of the experimental analysis of behavior were numerous, and we will mention only some of the more important ones here. He recognized a methodological analogy between particle emission in physics and the emitted character of spontaneous voluntary action. Many categories of behavior are emitted in the simple sense that they will occur from time to time. Skinner adopted the unique strategy of scientifically studying these emitted behaviors – which he called operants, because they generally operate upon the environment to change it – and he explored their systematic and quantitative relationship to motivational variables, and to a host of reward and punishment (or reinforcement) parameters. He formulated a precise vocabulary whose terms were defined by reference to the observable properties of the stimuli used and the behavior recorded, and coined the phrase, "the experimental analysis of behavior", to describe this type of research.
From the outset, Skinner emphasized the importance of detailed prediction and control of individual behavior. His own researches were invariably characterized by a great many measurements on very few organisms, with the reproducibility of the process under study as the test for reliability. Skinner's focus on the rate of a representative operant response has avoided many of the problems associated with more indirect measures of behavior. Thorndike had observed the number of errors made and the time taken to achieve success in his puzzle box, but neither of these was a property of the instrumental (that is, operant) behavior that was being acquired, if we wish to train a dog to jump through a hoop, for instance, we are less interested in the errors he makes, than in the hoop jumping itself. Errors are a measure of responses other than those we are in the process of investigating. Interesting questions about whether or not a given act will occur, or how often it will occur, can, however, be answered by Skinner's basic measure, rate of response.
The empirical basis of the experimental analysis of behavior has been gradually, but steadily, broadened. Starting from the lever-pressing of rats for food, many other responses, reinforcers and species have been examined and it has been possible to thereby show that principles derived from the original situation can be generalized to many other superficially dissimilar situations and, most importantly, to ourselves. Clearly the scope of the experimental analysis of behavior would be limited and its progress very slow if it had turned out that principles coming from one experimental situation did not apply to substantially different situations, or had no relevance to human behavior.
In the last forty years of the twentieth century, the successes of the experimental analysis of behavior have led to many applications of the principles that have emerged in the laboratory in dealing with serious real-world human problems. These applications have led in turn to the development of further principles that arise primarily in real-world applications, rather than in the laboratory. In this text we seek to introduce principles of both "pure" and applied behavioral analysis.
The move to applications was initially promoted by Skinner (1953), but was taken up by a vast number of investigators. Many of these were clinical psychologists who saw in applied behavioral analysis the possibility of introducing techniques to their work that would be effective in bringing about behavior change. Some early studies involved engaging human participants in procedures that closely resembled Skinner's experimental studies with animals. For example, Lindsley (1960) examined the rate of lever press responding in psychiatric patients when this behavior was followed by presentation of money as a reinforcer. He found that the amount of lever pressing was a sensitive index of the current level of psychotic behavior, with lever pressing increasing as the frequency of psychotic behavior declined. More typically, many early studies showed that if an appropriate reinforcing stimulus was arranged to occur following socially-acceptable or personally-useful behavior, then that behavior increased in frequency while other destructive or socially unacceptable behavior declined. In making these applications to the behavior of human adults, it was often necessary to select reinforcers that were effective for particular individuals. These might include events as diverse as attendance at church services (Ayllon & Azrin, 1968) or feeding a kitten (Lindsiey, 1956).
The behavioral orientation of applied behavioral analysis distinguishes it from all other approaches to ameliorating human psychological problems, most notably from those that derive from either a medical or a psychodynamic model. This behavioral orientation involves an initial behavioral assessment of the problem, the specification of behavioral objectives (that is, the changes in behavior that would be desirable), the use of an intervention strategy derived from the experimental analysis of behavior, and an assessment of whether the behavioral objectives have been achieved. As applied behavioral analysis developed, most attention was directed to the use of effective intervention strategies and demonstrations that behavioral objectives had been achieved following intervention. By 1968, there was a sufficient level of activity to support the publication of a specialist academic journal, the Journal of Applied Behavior Analysis, and the amount and range of work conducted has grown tremendously since then.
Some of the pioneers in this field (Baer, Wolf, & Risley, 1968) proposed some defining features of applied behavior analysis that are still useful today. It is applied in that the problems studied are those that are important to society rather than those crucial to theory development; it is behavioral in that it asks how it is possible to get an individual to do something effectively; and it involves analysis, and thus requires a demonstration of the events that can be responsible for the occurrence of the behavior in question. Other features are that it must be effective, in that substantial behavior change must be produced, and the behavior change should show generality. That is, it endures over time, and is also seen in a range of situations.
As noted earlier, this approach is not confined to clinical psychology and applications continue to be developed in an increasing number of areas. It can now be argued that applied behavioral analysis is capable of embracing the whole field of applied psychology (Goldstein and Krasner, 1987).
The experimental analysis of behavior, on the one hand, and applied behavior analysis, on the other hand, can be seen as the science and technology of behavior, as the former is concerned with the elucidation of basic scientific principles while the latter is concerned with their real-world applications. However, we are describing a new science and an even newer technology, and, not surprisingly the relationship between this science and technology is still under development and a matter for continuing debate among researchers.
By 1980, there were many areas in which applied behavioral analysis had been shown to be useful in dealing with serious human behavioral problems. It had often been "the treatment of last resort" in the sense that a "case" (for example, of a child with moderate intellectual disability who showed a severe level of self-injurious behavior through gouging at his face with his hand) had been approached using applied behavioral analysis only after more conventional medical and psychological treatments had failed to be effective. When applied behavioral analysis succeeded in producing behavioral improvements in such cases, great impetus was given to its use in similar cases, and it became more likely that it would become the preferred initial approach to this type of behavioral problem.
These early successes were important for the development of applied behavior analysis, but also led to an approach which some recent commentators have seen as excessively technological (for example, Hayes, 1991), in that it is concerned solely with the meticulous implementation of well-established procedures directed at significant human problems and not at all directed at basic research questions. If this trend continues, Hayes argued, there would not be an adequate basic science to generate useful applications, These issues have resulted in calls (for example by Mace, 1994a, Wacker, 1999) for research that bridges between experimental analysis and applied analysis of behavior, The bridge should be a two-way connection, with developments in each field informing the other. Mace suggested three important strategies: (a) the development in the laboratory (with other species) of models of human behavioral problems using operations that resemble those thought to be important in human life, (b) replication (repetition) of the same experimental design with humans in a laboratory setting, and (c) tests of the generality of the model with real-world problems in natural settings. Through such strategies, applied behavior analysis is moving away from being concerned almost exclusively with the application of a simple model of operant conditioning to human problems, and towards embracing the implementation of an ever-increasing range of behavioral principles.
In the early days of applied behavioral analysis, when practitioners were mostly concerned with the simple strategy of implementing an operant conditioning procedure, there were successes, but also a considerable "unevenness" in treatment outcomes. That is, not every person showing a particular problem, such as self-injurious behavior, was helped by the behavioral intervention methods typically used. A major breakthrough on this issue began with the work of Iwata, Dorsey, Slifer, Bauman, and Richman (1982) on self-injury. They noted that earlier work had focused on specifying behavioral objectives and implementing treatment, but had paid little attention to establishing the environmental determinants of self-injury prior to any intervention. That is, the question as to why the behavior was occurring was not being properly addressed. They remedied this by devising operant methods for assessing functional relationships between self-injury and the physical and social environment. In that study, and subsequent ones, they found that self-injury occurs for different reasons in different people. Persons that engage in self-injury may do it because it results in attention from others, because it allows them to escape from other demands (such as doing school work), because it raises the level of sensory stimulation, or for a combination of these reasons, importantly, behavioral interventions become much more effective when the treatment strategy for each individual is directly based on a prior functional analysis of their behavior.
Methods of functional analysis have now been developed for many types of behavioral problem, and functional analysis is now seen as the key element in the behavioral assessment which should precede any behavioral intervention. We noted in Section 1.7 that Skinner (1938) stated that functional relationships between aspects of behavior and parameters of the environment should be the goal of a science of behavior. With the increasing prominence of functional analysis in behavioral assessment, along with the use of functionally-defined behavioral intervention, functional relationships can now be seen as the central feature of applied behavioral analysis as they are in the experimental analysis of behavior.
Progress towards a scientific account of human behavior has been erratic. Although interest in it is very long standing, and dates back at least as far as Aristotle in the fourth century BC, the centuries-long domination in the Western world of religious explanations of human action made scientific progress slow. In the seventeenth century AD, Descartes provided a new dualistic framework which facilitated scientific accounts of animal behavior and even human physiology, but still impeded a scientific account of human behavior.
From the eighteenth century, developing knowledge of reflexes indicated that parts at least of the nervous system could be analyzed scientifically. I.P. Pavlov took a giant step beyond this in the late nineteenth and early twentieth century by demonstrating conditioned reflexes, or classical conditioning, in the dog. Pavlov realized that he was investigating how interaction with the environment modifies subsequent behavior in individual organisms, and he suggested that his conditioning paradigm could account for much learning and adaptation in animal behavior.
Conceptions of the relationship between human behavior and that of other animals changed radically in the late nineteenth century, following publication of Charles Darwin's theory of evolution by natural selection which implied that similar behavioral processes should be seen in humans as in other species. Also in the late 19th century, E.L. Thorndike's work on the law of effect and problem solving behavior illustrated such a behavioral process. If kittens, dogs, and chicks can "learn through experience" of the effects of their behavior, it seemed likely that this process affects humans as well as many other species.
Major shifts in the intellectual landscape usually come about through the promotional zeal of individuals, and in the early twentieth century behaviorism was fervently and brilliantly promoted as an alternative to the prevailing mentalism by J.B. Watson. Although few scientific data were available, Watson saw the potential of a science of behavior, which would be applicable to humans and to other species. Beginning in 1930, B.F. Skinner began to provide those scientific data by building on Thorndike's findings and establishing the branch of science known as the experimental analysis of behavior. Not only did he improve experimental techniques and thus show powerful control of animal behavior in laboratory experiments, but he also spent much of his long career suggesting how the findings of the experimental analysis of behavior could be extrapolated to explain much human behavior in real world settings.
Since 1960, those speculations about human behavior have been replaced by applied scientific data. In the developing field of applied behavior analysis, principles of behavioral analysis derived from laboratory studies are deployed in the explanation and amelioration of human behavioral problems. This applied science has progressed more rapidly in recent years, because the importance of functional analysis has been recognized. A successful functional analysis reveals the functions that a class of behavior currently has for an individual, and thus provides a sound basis for an intervention intended to change the frequency of that class of behavior.