Ivan Pavlov was a Russian physiologist best known for his groundbreaking work in the field of psychology. He is most famous for his experiments with dogs, where he discovered the concept of classical conditioning. In these experiments, Pavlov noticed that dogs would salivate not only when they were presented with food but also when they heard the sound of a bell that had been paired with feeding time. Pavlov's findings laid the foundation for understanding how behaviors can be learned through association. His work has had a lasting impact on psychology, influencing various fields, including behaviorism and cognitive psychology. Today, his research continues to be relevant in understanding learning and behavior.