The goal of classical conditioning is for a conditioned stimulus to elicit

VI. Summary

Classical conditioning theories have become considerably more complex since the early formulations by O. H. Mowrer and others. Modern conditioning models emphasize the role of cognitive factors such as memory processes and expectancies in the etiology and maintenance of conditioned responses. As theories of fear have developed, other pathways to fear acquisition have been added, although classical conditioning continues to be seen as important. Classical conditioning theories have led to a number of important treatments, with the most widely used being the exposure therapies for reducing fear. According to contemporary views, extinction of the CR can be regarded as a process of exposure to corrective information. Exposure involves having the person repeatedly exposure himself or herself to a feared stimulus until fear abates. Patients play an active role in choosing what they will be exposed to, and when the exposure will occur. Exposure therapies can successfully reduce conditioned fears and fears arising from other forms of learning.

Of the exposure therapies, graded in vivo exposure and flooding are among the most effective treatments of phobias, and play an important role in treating disorders in which fear plays a prominent role (e.g., social phobia, agoraphobia). For patients who are extremely phobic, the least demanding form of exposure (systematic de-sensitization) is typically the exposure intervention to be used first. Graded in vivo exposure is particularly important because it involves teaching patients skills for overcoming their fears. Patients can continue to apply these skills on their own, without the aid of a therapist. Exposure therapies can be combined with other psychological interventions, such as relaxation training and cognitive restructuring. For the average phobic patient, combination treatments tend to be no more effective than exposure alone. However, there are likely to be exceptions to this rule, and some patients may benefit most from a combination of psychotherapeutic procedures. Combining exposure with antianxiety drugs does not improve outcome, and may actually impair the effects of exposure. The benefits of exposure therapy tend to be long lasting, with no evidence of symptom substitution. Patients sometimes relapse, although their reemergent fears can usually be successfully treated with a further course of exposure therapy.

2 Basic Conditioning Procedure

The procedure of classical conditioning consists of the repeated presentation of two stimuli in temporal contiguity. First, a neutral stimulus (NS) is presented—that is, a stimulus that does not elicit regular responses or responses similar to the unconditioned response (UR). Immediately after that, the US is presented. Because of this pairing, the NS will become a CS and, therefore, will be capable of provoking a conditioned response (CR) similar to the UR that, initially, only the US could elicit (Fig. 1).

On the initial trials, only the US will elicit the salivation response. However, as the conditioning trials continue, the dog will begin to salivate as soon as the CS is presented. In salivary conditioning, the CR and the UR are both salivation. However, in many other conditioning situations, the CR is very different from the UR. According to Pavlov, the animals learn the connection between stimulus and response (CS–UR). Currently, it is understood that animals learn the connection between stimuli.

Publisher Summary

This chapter provides an overview of classical conditioning concept in learning behavior. While classical conditioning is often thought of as a simpler form of learning than operant conditioning; in fact, the complexity of classical conditioning from a procedural viewpoint rivals that of operant conditioning. It is generally agreed that classical conditioning, along with operant conditioning, constitutes the majority, if not all, of the learned behaviors. In general, classical conditioning involves the pairing of two stimulus events, typically a neutral conditioned stimulus (CS), and an unconditioned stimulus (US). That an association between these two events is learned is reflected in the acquisition of a conditioned response (CR) to the CS. The CR is usually topographically similar in the form to the unconditioned response (UR) to the US, although this is not universally the case. However, for classical conditioning the CR in no way changes the CS–US stimulus arrangements. One area where classical conditioning has been used extensively is in the study of drug effects on learning or acquisition. Classical conditioning procedures hold a number of advantages over operant conditioning in the study of learning.

Classical Conditioning of the Eyeblink Response

Whereas Ivan Pavlov discovered the phenomenon of classical conditioning using a conditioned reflex in the autonomic nervous system, the conditioned reflexes used in contemporary studies of classical conditioning, such as the conditioned eyeblink response, are controlled in the central nervous system. Skeletal muscle innervated by the cranial nerves controls the eyeblink. Eyeblink classical conditioning is a common paradigm for investigations of classical conditioning in general and classical conditioning in normal aging in particular. Fear conditioning, in which a neutral CS is paired with a moderately painful US, is another promising model system that has been elaborated extensively on a behavioral and neurobiological level. Studies of aging effects on fear conditioning have been reported, but the results are not consistent. The magnitude of age-related fear responses appears to be small, especially in comparison with age-related changes in eyeblink classical conditioning.

The neural circuitry that supports classical conditioning of the eyeblink response is almost completely mapped, and the behavioral and neurobiological parallels in this form of associative learning extend to all mammals that have been studied, including humans. Processes of normal aging affect eyeblink classical conditioning similarly in all species in which older organisms have been tested – mice, rats, rabbits, cats, and humans.

For several decades, the promise of eyeblink classical conditioning as a model system for the study of learning and memory in aging has been evident. Among the significant advantages of this model system for investigating processes of normal aging are that (1) age differences in the classically conditioned eyeblink responses are large and (2) striking parallels exist between the age differences in eyeblink conditioning in nonhuman mammals and humans. The initial parallels in normal aging and eyeblink conditioning were demonstrated between rabbits and humans. On no other species is there such a large body of parametric data on classical conditioning as on the classically conditioned eyeblink response in the rabbit. Indeed, much of the general literature on classical conditioning is based on data collected in the rabbit with the nictitating membrane (third eyelid of the rabbit) response and in the human with the eyeblink. Now techniques for behavioral and electrophysiological testing in rats, including neonatal rats, have been developed, along with techniques to test eyeblink conditioning in normal, mutant, and transgenic mice and rodent slice preparations.

Ernest Hilgard was the first to study eyeblink classical conditioning in animals and did classic studies on human eyeblink conditioning as well. His work established the close correspondence in properties of the conditioned eyeblink response in humans and others animals, suggesting that the underlying neuronal mechanisms of memory storage and retrieval are the same in all mammals, including humans. Here, perhaps more than in any other form of learning, neuronal mechanisms of memory elucidated in infrahuman mammals apply directly to the human condition. Isadore Gormezano was the first to publish eyeblink conditioning studies in the rabbit and to introduce measurement of the nictitating membrane extension response.

Initial research on aging and classical conditioning studied rabbits or humans. However, there are advantages of other species, such as mice and rats, for research on aging. In particular, mice and rats, with their short gestation period, large litter size, relatively small space requirements, and short life spans, are highly desirable for research on development and aging. Neither the genetic controls nor the breeding environments presently available for rabbits equal those in place for the mouse and rat. Consequently, many of the recently published studies on eyeblink classical conditioning, including those on aging, involve rodent subjects.

What is the goal of classical conditioning in psychology?

Is classical conditioning elicited?

What is classical conditioning purpose?

What elicits a response in classical conditioning?