Although their roots can be found at the beginning of the twentieth century, modern behavioral and cognitive–behavioral therapies arose during the 1950s and early 1960s when the scientific study of behavior emerged as a subject with validity in its own right. Disordered behavior was no longer taken to be purely a symptom or indicator of something else going on in the mind. Of inherent concern was its relation to past and current environmental events thought to be causally related to that behavior. Methods developed in animal laboratories began to be tested—in laboratory, institutional, clinical, and school settings—with people who had chronic mental illness or intellectual disabilities and with predelinquent adolescents. Improvements in patient behavior and functioning were often striking. These changes took place against a backdrop of growing dissatisfaction with the prevailing notion that psychopathology typically arose from unobservable psychic causes that were assessed and treated using techniques that seemed to be based more on art than science. In addition, an accumulating literature of outcome studies revealed that much of the psychotherapy as it had been practiced until the early 1960s engendered very modest and largely unpredictable results. Thus, contemporary behavior therapies emerged from three distinct psychological traditions: classical or Pavlovian conditioning, instrumental or operant conditioning, and cognitive–behavioral and rational–emotive therapies.

Classical Conditioning

The first major perspective within learning theory approaches is typically referred to as classical conditioning. This perspective dates to the first decade of the twentieth century and is largely attributed to the Russian neurophysiologist Ivan Pavlov. Pavlov was interested in studying the structure of the nervous system, in particular, simple reflex arcs between external events (stimuli) and an organism’s behavior (response). He chose to study salivation in dogs in response to food and developed an apparatus that held the dogs suspended in a harness while a small amount of meat powder was deposited on their tongues. He would vary the amount and timing of the delivery of the meat powder and recorded the subsequent variation in the nature and amount of salivation.

What happened next confounded his simple neurologic experiments but opened the way to revolutionary new insights regarding how organisms learn to adapt their behaviors in response to novel environments. Pavlov found that, after a few trials, his dogs began to salivate when strapped into the harness, well in advance of any exposure to the meat powder on a particular trial. Naïve dogs placed in the harness for the first time did not salivate; experienced dogs that had been through the procedure earlier began to salivate well in advance of the delivery of the food. In effect, the dog’s response came to precede the food stimulus, something that could not be explained in terms of a simple reflex arc.

Pavlov’s genius lay in recognizing the importance of this observation. He shifted his attention from the study of simple reflex arcs to those conditions necessary to support changes in behavior as a consequence of prior experience, that is, learning. He sounded a bell to signal the start of a trial that was followed by the delivery of meat powder and found that he could reliably train the dogs to salivate to the sound of a bell and not to respond to other aspects of the experimental situation. In effect, he introduced a particularly salient stimulus that carried all the predictive information contained in the situation (ringing the bell predicted subsequent delivery of meat powder, whereas nothing happened until the bell was sounded); and the dogs came to salivate reliably only after the bell was rung. Once the bell was established as a particularly informative stimulus, he could occasionally omit the meat powder on subsequent trials, and the dogs continued to salivate to the sound of the bell.

This simple paradigm contained the key elements of classical conditioning. The meat powder represented what Pavlov came to call the unconditioned stimulus. All dogs with intact nervous systems salivate in response to meat powder being deposited on their tongues, whether they have any experience with that stimulus or not. Salivation represented the unconditioned response. The bell (or earlier, the entire experimental apparatus) represented the conditioned stimulus. Dogs do not naturally salivate to the sound of a bell, but they come to do so if it is paired with the meat powder (the unconditioned stimulus). Salivation to the bell alone represented the conditioned response, a learned response to an originally neutral stimulus that is not found universally among all members of the species.

Early Demonstrations in Humans

J. B. Watson, one of the leading figures in American psychology, recognized the potential relevance of classical conditioning as an explanation for the development of symptoms of psychopathology. Watson and a graduate student conducted a demonstration of how the principles of classical conditioning explicated by Pavlov could be extended to humans. In this study, Watson first showed that a 3-year-old boy called Little Albert had no particular aversion to a small white laboratory rat: He would reach for it and try to pet it, as young children are inclined to do. Watson and his assistant then placed a large gong out of sight behind Little Albert and sounded it loudly every time they brought the rat into the room. Although Little Albert had shown no initial aversion to the rat, he showed a typical startle response to the sounding of the gong (again, as most young children would). Before long, he became upset and burst into tears at the sight of the rat alone and would try to withdraw whenever it was brought into the room.

According to Watson, this study demonstrated that phobic reactions could be acquired purely on the basis of traumatic conditioning. Although Little Albert had previously been intrigued by the presence of the rat and showed no evidence of any fear in its presence, pairing of the rat (the conditioned stimulus) with the loud, unpredictable noise produced by the gong (the unconditioned stimulus) led him to become anxious and upset in the rat’s presence (the conditioned response), just as he had naturally become upset by the sound of the gong (unconditioned response). He had not only acquired a fear response to the rat but also tried to escape from it or avoid exposure to it. According to Watson, Little Albert had acquired the two hallmarks of a phobia (unreasonable fear, and escape or avoidance behaviors) purely as a consequence of simple classical conditioning.

The next major study in the sequence was conducted by Mary Cover Jones in 1924. She reasoned that, if classical conditioning could produce a phobic reaction in an otherwise healthy child, the same laws of learning could be used to eliminate that reaction. She trained a young child to have a conditioned fear response to a small animal (a rabbit) and then proceeded to feed the child in the presence of the rabbit. She found that pairing of the conditioned stimulus (the rabbit) with a second, unconditioned stimulus (food)—which produced a different unconditioned response (contentment) that was incompatible with the first (anxiety)—came to override the original learning. The child began to relax in the presence of the rabbit and no longer showed the fear response that he had acquired earlier. Thus, Jones argued, she was able to provide relief via counterconditioning.

Despite these early demonstrations, it was several decades before behavioral principles were applied systematically to the treatment of psychiatric disorders. This delay resulted partly from the sense that these procedures were just too simplistic to be of practical use in the treatment of complex human problems. Required were methods based on these learning principles that could be adapted to deal with more complex problems of living. Andrew Salter provided the first such method. In a text that was ahead of its time, Salter described a series of procedures based on principles of conditioning that were suitable for addressing emotional and behavioral problems in human patients. Although that text attracted little attention when it was published in 1949, it described (in vestigial form) many of the strategies and procedures that would later be used in the clinical practice of behavior therapy.

Applications to Clinical Treatment

Joseph Wolpe provided the first coherent set of clinical procedures, based on principles of classical conditioning that had a major impact on the field. Wolpe had studied experimental neuroses in cats. In the course of his studies, which involved shocking animals when they tried to feed and observing the results of the conflict this produced, Wolpe replicated the essential features of Jones’s earlier attempt to reduce a learned fear via the process of counterconditioning. He soon extended his work to people with phobic disorders and was able to reduce his patients’ distress by pairing the object of their fear with an activity that reliably produced an incompatible response. Like Salter, he experimented with the induction of anger and sexual arousal before finally settling on a set of isometric exercises developed to help reduce stress in patients with heart conditions. This procedure, called progressive relaxation, consists of having patients alternately tense and relax different muscle groups in a systematic fashion and can lead to a state of profound relaxation. The isometric exercises could be paired with the presumably conditioned stimulus (whatever the patient feared) in order to have the new conditioned response (relaxation) override the existing arousal and distress that patients experienced in the presence of the phobic stimulus.

Wolpe called his approach systematic desensitization. In progressive relaxation training a hierarchy is developed that represents successive degrees of exposure to the feared object or stimulus. For example, a patient with fear of flying might be asked to visualize a variety of scenes that induce differing amounts of anxiety. Simply watching someone else board an airplane might induce only a minimal amount of anxiety, whereas boarding a plane oneself and flying through a thunderstorm would be expected to elicit more anxiety. Wolpe worked with the patient to develop a hierarchy of such imagined experiences and grade them on a scale from 0 to 100 in terms of how much distress they produced. He would then expose the patient to these stimuli (typically in imagination). He proceeded on to the next item in the hierarchy only when the client could tolerate a particular image without experiencing distress. If the patient started to become upset while visualizing an image, Wolpe would instruct the patient to stop the image and reinitiate the relaxation exercises until the feelings of arousal had passed. In this fashion, he systematically worked the patient through the hierarchy of representations of the feared object, proceeding as rapidly as the patient could without experiencing distress until the stimulus no longer elicited any anxiety.

Hundreds of studies have suggested that systematic desensitization (or its variants) is effective in the treatment of phobia and related anxiety-based disorders. Systematic desensitization has been applied widely to a host of problems and represents a safe and effective way of reducing anxious arousal in both adults and children. Major variations include substituting meditation or biofeedback for progressive relaxation as a means of producing the relaxation response (some people do not respond well to muscular isometrics) or arranging experiences in a graduated fashion. The basic approach appears to be robust to these minor modifications and is one of the few examples of a treatment intervention that is truly more effective than other interventions.

Extinction & Exposure Therapy

Despite its evident clinical utility, systematic desensitization is based on a misperception of the laws of classical conditioning. Classical conditioning is essentially ephemeral. Organisms stop responding to the conditioned stimulus when it is no longer paired with the unconditioned stimulus. Pavlov’s dogs may have learned to salivate to the ringing of the bell, but if Pavlov kept ringing the bell after it was no longer paired with the meat powder, the dogs soon stopped salivating to its ring. This is referred to as the process of extinction, in which conditioned stimuli lose their capacity to elicit a response when they are presented too many times in the absence of the unconditioned stimulus.

This basic feature was considered so troublesome by early behaviorally oriented psychopathologists that they felt compelled to explain how such an ephemeral process could account for a long-lasting disorder such as a phobia (most phobias do not remit spontaneously over time). O. Hobart Mowrer solved the riddle when he postulated that phobic reactions essentially involve two learning processes: classical conditioning, to instill the anxiety response to a previously neutral stimulus; and operant conditioning, to reinforce the voluntary escape or avoidance behaviors that remove the patient from the presence of the conditioned stimulus before the anxious arousal can be extinguished. In essence, people who acquire a phobic reaction to a basically benign stimulus do not extinguish (as the laws of classical conditioning predict they should), because they do not stay in the situation long enough for classical extinction to take place.

This conclusion led some behavior theorists to suggest that although systematic desensitization was undoubtedly effective, it was unnecessarily complex and time consuming. The essential mechanism of change, they suggested, was extinction, not counterconditioning, and the only procedure needed was to expose the patient repeatedly to the feared object or situation. Of course, the therapist would also have to do something to prevent the patient from running away or otherwise terminating contact with the feared situation. Thus, according to exposure theorists, it was not necessary to ensure that patients experienced no fear in the presence of the phobic stimulus (as Wolpe claimed). Rather, all that was required was to get them into the situation and to prevent them from leaving until the anxiety had diminished on its own.

Several decades of controlled research have suggested that the extinction theorists were correct and that exposure (plus response prevention) is at least as effective as systematic desensitization and is more rapid in its effects. That does not necessarily mean that it is more useful than systematic desensitization in practice; many patients find exposure therapy very distressing and prefer the gentler alternative provided by systematic desensitization. Although exposure typically works more rapidly than does systematic desensitization (and both work more rapidly than do nonbehavioral alternatives), it often takes as long to persuade a patient to try exposure techniques as it does to complete a full course of systematic desensitization. Nonetheless, it is now clear that exposure (with response prevention) is a sufficient condition for symptomatic change and that Wolpe was in error when he suggested that allowing a patient to experience anxiety in the presence of the phobic situation delayed the process of change. Although patients who already have acquired a conditioned fear response will undoubtedly experience distress when exposed to the object of their fears, the fact that they become anxious during the course of that exposure neither facilitates nor retards the extinction process. (This is why most behavior therapists no longer use the term “flooding” to refer to exposure therapy; although it may be descriptive of the level of anxiety induced, it is misleading in that it seems to imply that the induction of anxiety is itself curative in some way.)

Exposure plus response prevention has a clear advantage over systematic desensitization (and virtually every other type of nonbehavioral intervention) in the treatment of more complex disorders related to anxiety. It appears to be particularly helpful in the treatment of obsessive–compulsive disorder (OCD) and severe agoraphobia. For example, treatment for a patient who has a fear of contamination and repetitive hand-washing rituals might involve having a therapy team spend a weekend locked in the patient’s home, having the patient intentionally contaminate his or her hands and food with dirt (by shutting off the water to prevent hand washing). Similarly, a patient with severe agoraphobia would be encouraged to visit settings that he or she typically avoids (e.g., shopping malls or grocery stores) during the busiest times of the day and would be prevented (again by a therapy team or group) from leaving until his or her anxiety had subsided. Although systematic desensitization has had limited success with such severe disorders, the process of constructing and working through the literally dozens of hierarchies required typically makes the approach wildly impractical.

Summary

Strategies based on classical conditioning have been used in the treatment of depression, somatoform disorders, dissociative disorders, substance abuse, sexual difficulties, medical problems, and a variety of other disorders. In general, these approaches represent some of the most effective of the therapeutic interventions. As is the case with other types of behavioral strategies, they rest on a solid foundation of empirical work, much of it with nonhuman animals, and on the creative adaptation of those basic principles to human populations.

Emergence of Instrumental & Operant Learning Theory

As a graduate student at Columbia University, Edward Thorndike began a series of experiments that set a new course in the study of processes underlying behavior change and learning. He placed a cat in an enclosed chamber and attached a vertical pole in the center of the compartment to a rope that passed over several pulleys. When the cat bumped against the pole, the pole would tilt, causing the rope to open the door. The cat could then leave the compartment and drink milk from a nearby bowl outside the cage. At first, the cat seemed to move about unpredictably each time it was returned to the compartment. The time required for the cat to tilt the pole grew shorter on successive repetitions of the task, and the cat’s method for opening the door on each trial became progressively similar to the method used on the preceding trial. The trial-by-trial record of time to escape from what Thorndike called his “puzzle box” was the first instrumental learning curve published in a scientific journal. Eventually, each cat quickly approached the pole—seemingly purposively—and tilted it to one side, opening the door. Thorndike described this as an instrumental conditioning process because the pole tilting was instrumental in releasing the cat from the chamber and permitting access to a reward. Thorndike’s method differed from Pavlov’s classical conditioning because no specific response was elicited by a conditioned stimulus. The form of each cat’s behavior that tilted the pole was idiosyncratic and variable. There was nothing fixed about the behavior, as was typical of classically conditioned behavior. Thorndike’s Law of Effect described the necessary and sufficient conditions for instrumental learning to occur.

Skinner & Operant Behavior