Final answer:
Ivan Pavlov is most similar to John B. Watson in his approach to psychology.
Step-by-step explanation:
Ivan Pavlov, a Russian scientist, is most similar to John B. Watson in his approach to psychology. Both Pavlov and Watson were behaviorists who focused on observable behavior rather than inner experiences. Pavlov is known for his experiments in classical conditioning, which involved training dogs to associate a stimulus (such as a sound) with a reflex response (such as salivation). Watson, influenced by Pavlov's work, championed the idea that all behavior can be studied as a simple stimulus-response reaction without consideration of internal processes.