Classical conditioning

Classical conditioning (also Pavlovian conditioning or respondent conditioning) is a type of associative learning found in animals. These associations are formed by pairing two stimuli--what Ivan Pavlov described as the learning of conditioned behavior-- to condition an animal to give a certain response. The simplest form of classical conditioning is reminiscent of what Aristotle would have called the law of contiguity which states that: "When two things commonly occur together, the appearance of one will bring the other to mind."

Overview
The typical paradigm for classical conditioning involves repeatedly pairing a neutral stimulus with an unconditioned stimulus.

An unconditioned stimulus is a stimulus that elicits a response--known as an unconditioned response--that does not need to be learned by the animal. The relationship between the unconditioned stimulus and unconditioned reponse is known as the unconditioned (or unconditional) reflex. The conditioned stimulus, or conditional stimulus, is an initially neutral stimulus that elicits a response--known as a conditioned response--that is learned by the animal. Conditioned stimuli are associated psychologically with conditions such as anticipation, satisfaction (both immediate and prolonged), and fear. The relationship between the conditioned stimulus and conditioned reponse is known as the conditioned (or conditional) reflex.

In classical conditioning, when the unconditioned stimulus is repeatedly or strongly paired with a neutral stimulus the neutral stimulus becomes a conditioned stimulus and elicits a conditioned response.

Pavlov's experiment
The most famous example of classical conditioning involved the salivary conditioning of Pavlov's dogs. Pavlov's dogs naturally salivated to food. Pavlov therefore called the one-to-one correlation between the unconditioned stimulus (food) and the unconditioned response (salivation) an unconditional reflex. If a tone (generated by a tuning fork, for example) was reliably sounded for a few seconds before food, however, the tone eventually came to elicit salivation even when the tone was presented without the food. Because the one-to-one correlation between the conditioned stimulus (tone) and the conditioned response (salivation) involved learning, Pavlov referred to this relationship as a "conditional reflex". The conditional reflex (food-related behaviour elicited by a stimulus that has been reliably paired with food) is said to be developed through classical conditioning.

The origins of the two reflexes are different. The food (unconditional stimulus) [UCS] causing salivation (unconditional response) [UCR] reflex has its origins in the evolution of the species. The tone (conditional stimulus) [CS] causing salivation (conditional response) [CR] reflex has its origins in the experience of the individual animal.

Behavioral therapies based on classical conditioning
In human psychology, implications for therapies and treatments using classical conditioning differ from operant conditioning. Therapies associated with classical conditioning are aversion therapy, flooding, systematic desensitization, and implosion therapy. Implosion therapy and "flooding" involve forcing the individual to face an object/situation giving rise to anxiety; both of these techniques have been criticized for being unethical since they have the potential to cause trauma.

Classical conditioning is short-term, usually requiring less time with therapists and less effort from patients, unlike humanistic therapies. The therapies mentioned in the last paragraph are intended to cause either aversive feelings toward something, or to reduce the aversion altogether. Classical conditioning is based on a repetitive behaviour system.

Aversion therapy
This is a form of psychological therapy that is designed to eliminate sexual behaviour by associating an aversive stimulus such as nausea with sex. Because the aversive stimulus performs as a UCS and produces a UCR, the association between the stimulus and behaviour leads to the same consequences each time. If the treatment has worked, the patient will not have a complusion to engage in such behaviours again. This sort of treatment has been used to treat alcoholism and drug addiction as well as--controversially--homosexuality and sexual perversions. Adams et al. (1981), states that these controversial treatments involved administering electric shocks to homosexuals to reduce the response to male nudes, and encouraging a heterosexual response to female nudes.

Systematic desensitization
Patients might learn that the object of their phobias or fears are not so fearful if they can safely relive the feared stimulus. However anxiety often obstructs such recovery. This obstruction is overcome by reintroducing the fear-producing object gradually. A person imagines a series of advancing fearful situations while the person is languid. The responses of irrational fear to the object are eventually rendered incompatible--known as reciprocal inhibition--and the fear is eventually removed if the therapy is performed correctly.