Final answer:
In classical conditioning, a neutral stimulus is paired with an unconditioned stimulus until it becomes a conditioned stimulus, eliciting a conditioned response.
Step-by-step explanation:
In classical conditioning, an unconditioned response is an automatic, natural reaction to an unconditioned stimulus, which does not require prior learning. During Pavlov's experiment, the unconditioned response was the dogs' salivation in reaction to the unconditioned stimulus - the food. On the other hand, a neutral stimulus is initially unrelated and does not naturally elicit a response from an organism. In the case of Pavlov's dogs, the ringing bell was a neutral stimulus.
Through repeated pairings of the bell (neutral stimulus) with food (unconditioned stimulus), the bell eventually evoked salivation. The bell became a conditioned stimulus, and the salivation in response to the bell became a conditioned response.