Preexposure to a conditioned stimulus retards the development of a conditioned response to that same stimulus compared with an unconditioned stimulus.

Conditioned Stimulus

An initially neutral stimulus that, after being linked with an unconditioned stimulus, starts to produce a conditioned response.

Conditioned Response

A conditioned response is an automatic reaction established by learning to an initially neutral stimulus after being repeatedly paired with an unconditioned stimulus that triggers an automatic response.

Unconditioned Stimulus

A stimulus that naturally and automatically triggers a response without prior learning or conditioning.