Final answer:
In Pavlov's experiments, the bell was the neutral stimulus, meat powder was the unconditioned stimulus, and salivation was the unconditioned response; after conditioning, the bell also became the conditioned stimulus eliciting the conditioned response of salivation.
Step-by-step explanation:
In Pavlov's original classical conditioning experiments, the bell was the neutral stimulus (NS), the meat powder was the stimulus that would elicit a reflex (known as the unconditioned stimulus, or UCS), and salivation was the reflexive response (termed the unconditioned response, or UCR).
During the conditioning process, Pavlov consistently rang a bell before presenting the dogs with meat powder. By doing so, the NS of the bell's tone gradually became a conditioned stimulus (CS), eventually eliciting the conditioned response (CR) of salivation on its own, indicating that the dogs had formed an association between the bell and the presentation of food.