John B. Watson was an American psychologist best known for founding the school of behaviorism. He believed that psychology should focus on observable behaviors rather than internal mental states. Watson's famous experiment with a baby named Little Albert demonstrated how emotions could be conditioned, showing that fear could be learned through association. Watson's ideas greatly influenced psychology and education, emphasizing the importance of the environment in shaping behavior. He argued that all human actions are a result of conditioning, which led to new approaches in therapy and learning. His work laid the groundwork for later psychologists, including B.F. Skinner and Albert Bandura.