Classical Conditioning

Description of the Strategy

The clinical applications of classical conditioning techniques have been widely accepted for both children and adult populations. However, treatment emphasis has often focused only on fear and anxiety reduction, an expectable consequence, given the historical development of classical conditioning theory. While a classical approach is effective with anxiety-based disorders, the clinical application of classical conditioning has a variety of uses. Moreover, classical conditioning procedures are significantly enhanced when used in conjunction with approaches based on operant learning theory.

Classical conditioning theory is most often related to the work of Ivan Petrovitch Pavlov. Pavlov worked on three research problems during his life: the function of the heart nerves, the primary digestive glands—which won him the Nobel Prize in 1904—and the analysis of conditioned reflexes. His work on conditioned reflexes followed a serendipitous discovery while investigating the digestive system of dogs.

When he noted, during this study, that an unlearned reflexive response to food, salivation, began to occur outside the presence of food, Pavlov became interested [Page 764]in the effects of external stimuli on reflexive behavior. He defined an unconditioned response as an innate function, which requires no learning to occur (e.g., placing food in a dog's mouth evokes salivation). Pavlov was fascinated by how a seemingly unrelated stimulus could come to elicit a reflexive response.

In Pavlov's original study, food served as the evoking stimulus, or unconditioned stimulus (US), and salivation was the unconditioned response (UR). This represented an unlearned reflexive relationship. Conditioning, then, required the systematic pairing of a neutral stimulus (an NS) with the US. A bell served as the NS and was presented immediately prior to the presentation of the food (US). Following a number of pairings of the bell (NS) and food (US), the bell came to elicit salivation. The bell comes to represent a conditioned stimulus (CS), which elicits the conditioned response (CR), salivation. While nothing is necessarily inherently different about this salivation, the CR salivation reflects the conditioning effects of the eliciting stimulus.

This paradigm serves as the basis for understanding how environmental stimuli may gain control over many reflexive behaviors. Once conditioned, however, these CS-CR relationships will only be maintained if the CS is occasionally paired with the US. In Pavlov's study, the newly acquired CS, the bell, had to be followed occasionally by the US, food. Without these occasional maintenance pairings, the bell lost its ability to elicit salivation. The process of specifically preventing these repeated pairings of the CS and US is referred to as extinction. Pavlov demonstrated the effects of extinction with his dogs by terminating the pairings of the bell and food. Over time, the CR (salivation) diminished until the bell no longer had any effect on salivation. Despite undergoing an extinction procedure, however, the CS would occasionally, again, elicit the CR, a phenomenon known as spontaneous recovery. Notably, this reappearing CS-CR can still be eliminated if the extinction procedure continues.

In addition to the basic conditioning and extinction procedures, Pavlov also demonstrated the effects of stimulus generalization and higher-order conditioning. Stimulus generalization refers to that situation in which stimuli similar to the training stimuli are presented and elicit the same CR. Obviously, the more closely the stimuli are related, the more likely stimulus generalization is to occur. Higher-order conditioning refers to using a previously conditioned stimulus to condition other stimuli to elicit responses.

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