Conditioned Stimulus: Any stimulus that, through conditioning comes to evoke a conditioned response. The CS is an originally neutral stimulus.

Conditioned Response: Any response which is learned or altered by conditioning. The CR is a response that comes to be elicited by a previously neutral stimulus.

Unconditioned Stimulus: Any stimulus that reliably elicits from an organism a particular unconditioned response.

Unconditioned Response: Any response that is reliably elicited from an organism by a particular unconditioned stimulus.

Neutral Stimulus: Any stimulus that does not naturally elicit the conditioned response and, as a result, can serve as a conditioned stimulus.

Contiguity: A state of close proximity or association either in space or in time of two or more events.


Lefrancois, G.R. (2000). Theories of Human Learing, What the old man said, Fourth Edition, Wadsworth Publishing Company: Belmont.

Creative Quotations: (2001) Ivan Pavlov Retrieved (August 15, 2001) from

A Science Odyssey: People and Discoveries: (1998) Ivan Pavlov Retrieved (August 15, 2001) from

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