A conditioned stimulus is presented repeatedly without the paired presentation of the US. After time, the subject no longer makes the conditioned response. This fading of the CR is known as habituation.

Conditioned Stimulus

An initially neutral stimulus that, after being associated with an unconditioned stimulus, comes to trigger a conditioned response.

Conditioned Response

A response acquired through learning to a stimulus that was once neutral but has become linked to an unconditioned stimulus due to conditioning.

Habituation

A decrease in response to a stimulus after repeated presentations; a simple form of learning.