conditioned response

n. Psychology
A new or modified response elicited by a stimulus after conditioning. Also called conditioned reflex.

A learned response performed by a trained animal to a signal that was previously associated with an event of consequence for that animal. Conditioned reflex (CR) was first used by the Russian physiologist I. P. Pavlov to denote the criterion measure of a behavioral element of learning, that is, a new association between the signal and the consequential event, referred to as the conditioned stimulus (CS) and unconditioned stimulus (US), respectively. In Pavlov's classic experiment, the conditioned stimulus was a bell and the unconditioned stimulus was sour fluid delivered into the mouth of a dog restrained by harness; the conditioned stimulus was followed by the unconditioned stimulus regardless of the dog's response. After training, the conditioned reflex is manifested when the dog salivates to the sound of the bell.

Ideally, certain conditions must be met to demonstrate the establishment of a conditioned reflex according to Pavlov's classical conditioning method. Before conditioning, the bell conditioned stimulus should attract the dog's attention or elicit the orienting reflex (OR), but it should not elicit salivation, the response to be conditioned. That response should be specifically and reflexively elicited by the sour unconditioned stimulus, thus establishing its unlearned or unconditioned status. After conditioned pairings of the conditioned stimulus and the unconditioned stimulus, salivation is manifested prior to the delivery of the sour unconditioned stimulus. Salivation in response to the auditory conditional stimulus is now a “psychic secretion” or the conditioned reflex.

To this day, Pavlov's methods provide important guidelines for basic research upon brain mechanisms in learning and memory. Scientists all over the world have paired a vast array of stimuli with an enormous repertoire of reflexes to test conditioned reflexes in representative species of almost all phyla, classes, and orders of animals. As a result, classical conditioning is now considered a general biological or psychobiological phenomenon which promotes adaptive functioning in a wide variety of physiological systems in various phylogenetic settings. See also Cognition; Memory.

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conditioned reflex

A response that is trained or learned. In classical conditioning, a conditioned response is elicited by a stimulus other than that which normally produces the response. In operant conditioning, a conditioned response is one that has become more frequent after being reinforced.

In psychology, the response made by a person or animal after learning to associate an experience with a neutral or arbitrary stimulus. Conditioned response experiments by Ivan Pavlov (see Pavlov's dogs) paired a neutral stimulus (sounding a bell) with a natural response (salivating) by associating the bell with the presentation of food. Conditioned response experiments by B. F. Skinner and other behaviorists (see behaviorism) associated an arbitrary action (an animal's pressing a lever) with a positive reward (presentation of food) or a negative reward (an electric shock).

Response conditioning is used in behavior modification. Stop-smoking clinics, for example, may use an electric shock whenever a patient lights up. The patient will then associate smoking with the unpleasant experience of the shock.