Define Unconditioned Stimulus

The term "unconditioned stimulus" is used in the theory of classical conditioning to refer to a stimulus that automatically and unconditionally elicits a response. This theory, developed by Ivan Pavlov, explains how experience causes people (and animals) to develop emotional responses to hitherto neutral stimuli through conditioning.

The Classic Study

• In Ivan Pavlov’s famous study on dogs, he noted that the presentation of food elicited the salivation response. Pavlov found that when another stimulus, such as the ringing of a bell, was presented simultaneously with the food repeatedly, the salivation response eventually was elicited by the bell alone.

Unconditioned Stimulus

• In Pavlov’s study, the scent of the food is the unconditioned stimulus. There was no training or experience required to get the dog to salivate to the presentation of food.

Unconditioned Response

• The unconditioned response is the response that naturally is elicited by the unconditioned stimulus. In Pavlov’s experiment, the scent of the food is the unconditioned stimulus, and salivation is the unconditioned response.

Conditioned Stimulus

• The conditioned stimulus is the stimulus that over repeated exposures becomes associated with the unconditioned stimulus. For example, in Pavlov’s study, the bell (conditioned stimulus) becomes associated with the food (unconditioned stimulus). Over time, the bell alone elicited a salivation response.

Conditioned Response

• The conditioned response becomes associated with the conditioned stimulus. Typically, the conditioned response will differ somewhat from the unconditioned response. In Pavlov’s experiments, the dog salivated less in response to the bell (conditioned stimulus) than it did to the presentation of the food (unconditioned stimulus).