In Ivan Pavlov's famous studies, the was the unconditioned stimulus, and the was the unconditioned response.

In Ivan Pavlov's famous studies, the food was the unconditioned stimulus, and the salivation was the unconditioned response.

Explanation:

Ivan Pavlov (1849-1936) was a Russian physiologist who conducted studies on behavior conditioning with dogs. In his studies, dogs would learn to associate different stimuli and produce certain responses.

A unconditioned stimulus is something that produces a natural, automatic response. That natural response is called unconditioned response. In Pavlov's studies with the dogs, he would show them food, and the dogs would start salivating because of it. That means the unconditioned stimulus was the food, and the unconditional response was the salivation.