Edward Thorndike was an American psychologist, professor and educator. He is renowned for his ‘Law of effect’ theory, animal research, and trial-and-error theory of learning. He is often referred to as the father of modern educational psychology. Born into a religious family, he excelled at studies and acquired several degrees from prestigious American institutions in his youth. During his doctoral studies, he conducted his famous puzzle box experiments with cats that led to the introduction of his groundbreaking work, ‘Law of effect’. Thereafter, he switched his focus to educational psychology. After an initial unhappy employment, he became a faculty at Columbia University, where he spent his entire career. During World War I, he even assisted the American armed forces in recruitment of soldiers based on his testing methodologies. As a result, he emerged as an expert in designing tests, which transferred to education, testing and employee exams as well. He held several prestigious positions in the American psychological field and authored many books. His research has influenced many fields like comparative psychology, behavior analysis, animal psychology, education, etc.