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.
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 ...