Classical conditioning (also Pavlovian conditioning or respondent conditioning) is a form of learning in which conditioned stimulus comes to signal the occurrence of an unconditioned stimulus, usually a biologically significant stimulus that elicits a response from the start called the unconditioned response.
Blocking occurs when prior experience with one stimulus prevents later conditioning to a second stimulus. The literature on blocking began with Leon Kamin in 1969. There are many theories as to why blocking occurs. Rescorla and Wagner favor the idea that only a certain amount of conditioning can be sustained by a given US. Later conditioning may be blocked simply because some limit has already been reached.
The evidence suggests that mental imagery can facilitate or diminish the outcome of classical conditioning in humans and, more tentatively, that mental images can substitute for actual US and CS in autonomic conditioning. They argue that researchers should explore the role of mental imagery in conditioning through the use of advances in the measurement of imagery. Finally, they analyze anxiety and trauma reactions as examples of how applied areas can be used to explore and benefit from developments in this area.
Classical conditioning also demonstrates how the fear response generalizes to related stimuli which can eventually develop into a full-blown anxiety disorder. Imagine a child walks by a Golden Retriever dog at a park who barks loudly at her. As a result, she becomes fearful of not only Golden Retrievers, but all dogs, parks with dogs in it, as well as large brown furry animals. This is the process of "generalization."
Pavlov noted that when his experimental subjects (dogs) were exposed to a naturally occurring stimulus (food), which he called the "unconditioned stimulus," a naturally occurring salivation response or "unconditioned response" was elicited. In a series of experiments, Pavlov paired the unconditioned stimulus (food) with a neutral "conditioned stimulus", the ringing of a bell. Each time the dogs were exposed to food, they also heard a bell ring (the conditioned stimulus). The pairing of the conditioned and the unconditioned stimuli was repeated multiple times. After a series of trials, the dogs eventually learned that the bell and the food went together -- they learned the connection between the two. As a result, when the they heard the bell in the absence of food, the dogs still salivated (now referred to as a conditioned response). What was a naturally occurring unconditioned response was now a conditioned response -- conditioned to the ringing of a bell!
Ivan Pavlov showed that classical conditioning applied to animals. Did it also apply to humans? In a famous (though ethically dubious) experiment Watson and Rayner (1920) showed that it did.
John Watson proposed that the process of classical conditioning (based on Pavlov’s observations) was able to explain all aspects of human psychology. Everything from speech to emotional responses were simply patterns of stimulus and response. Watson denied completely the existence of the mind or consciousness.
Conditioning, in physiology, a behavioral process whereby a response becomes more frequent or more predictable in a given environment as a result of reinforcement, with reinforcement typically being a stimulus or reward for a desired response. Early in the 20th century, through the study of reflexes, physiologists in Russia, England, and the United States developed the procedures, observations, and definitions of conditioning. After the 1920s, psychologists turned their research to the nature and prerequisites of conditioning.
In the act of classical conditioning, the learner comes to respond to stimuli other than the one originally calling for the response (as when dogs are taught to salivate at the sound of a bell). One says in such a situation that a new stimulus is learned. In the human situation, learning to recognize the name of an object or a foreign word constitutes a simple instance of stimulus learning.
Pavlov knew very well that performance in conditioning situations cannot be understood in terms of contiguity alone. It was he, after all, who discovered overshadowing: strong responding to B after reinforced training with B alone but very little after reinforced training with AB . Diminished responding to B alone after the AB training did not mean, Pavlov noted, that little had been learned about it; clear evidence to the contrary was provided by greater responding to AB than to A alone.
Extinction: in classical conditioning, the tendency for the response to the conditioned stimulus (called the conditioned response) to go away once the conditioned stimulus is no longer paired with the unconditioned stimulus. Note, however, that classically conditioned fears tend NOT to extinguish on their own, largely because people avoid exposure to the conditioned stimulus once they have become afraid of it.