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 Pavlov̵7;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 Pavlov̵7;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 Pavlov̵7;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 Pavlov̵7;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 Pavlov̵7;s experiments, the dog salivated less in response to the bell (conditioned stimulus) than it did to the presentation of the food (unconditioned stimulus).