Edward Thorndike was an American psychologist best known for his work in educational psychology and the development of the theory of connectionism. He is famous for his experiments with animals, particularly cats, which led to the formulation of the Law of Effect. This principle states that behaviors followed by satisfying outcomes are more likely to be repeated, while those followed by unpleasant outcomes are less likely to occur. Thorndike's research laid the groundwork for later theories in behaviorism and influenced the field of learning theory. His work emphasized the importance of reinforcement in learning and contributed to the development of practical applications in education, such as standardized testing and instructional design.