Ivan Pavlov was a Russian physiologist who won the 1904 Nobel Prize for his work on classical conditioning. Through a series of experiments using dogs, Pavlov discovered that animals could learn to associate stimuli with rewards through repeated pairings. He found that dogs could learn to associate the ringing of a bell with being fed, resulting in salivation upon hearing the bell alone. Pavlov's work established the basic principles of learning through conditioning and was highly influential on the field of behaviorism.