Edward Thorndike

Edward Lee Thorndike was an American psychologist who spent almost his whole career at Columbia University’s Teachers College. His research in comparative psychology and how learning happens produced his “theory of connectionism” and gave educational psychology a scientific foundation. He also tackled practical industrial problems, including designing employee exams and testing methods. Thorndike served on the board of the Psychological Corporation and was president of the American Psychological Association in 1912. A 2002 survey by *Review of General Psychology* ranked him the ninth most-cited psychologist of the 20th century. His law of effect became a basic framework for empirical laws in behavioral psychology, strongly influencing reinforcement theory and behavior analysis, and through that, classroom education.

Thorndike was born in Williamsburg, Massachusetts, to Edward R. and Abbie B. Thorndike; his father was a Methodist minister in Lowell. He graduated from The Roxbury Latin School in 1891, earned a B.S. from Wesleyan University in 1895, and an M.A. from Harvard in 1897. Both his brothers, Lynn and Ashley, became notable scholars—Lynn in medieval history of science and magic, Ashley as an English professor and Shakespeare authority. At Harvard, Thorndike worked with William James and became interested in how animals learn, later shifting his focus to human learning. His doctoral thesis is often considered a key document in modern comparative psychology. He completed his Ph.D. at Columbia in 1898 under James McKeen Cattell, a founder of psychometrics. After an unhappy year teaching at the College for Women of Case Western Reserve in Cleveland, he joined Teachers College in 1899 as an instructor in psychology and stayed there for his entire career, studying human learning, education, and mental testing. In 1937 he became the second president of the Psychometric Society, following Louis Leon Thurstone. He married Elizabeth Moulton on August 29, 1900; they had five children, including Frances, who became a mathematician. Early in his career, Thorndike bought a large tract of land on the Hudson River and encouraged other researchers to settle nearby, forming a colony where he acted as a kind of tribal chief.

Thorndike was a pioneer in behaviorism, learning research, and using animals in clinical experiments. His doctoral dissertation, “Animal Intelligence: An Experimental Study of the Associative Processes in Animals,” was the first psychology study to use nonhuman subjects. He wanted to know if animals could learn through imitation or observation, so he built puzzle boxes—roughly 20 inches long, 15 inches wide, and 12 inches tall—with a door opened by a weight-and-pulley system triggered by a lever or button inside. He placed animals, mostly cats, inside and measured how long they took to escape. At first they wandered and meowed, but eventually they accidentally stepped on the switch, opened the door, and received a food reward. Thorndike found that cats did not learn faster by watching others escape, nor by having their paws placed on the correct lever. This led him to a trial-and-error explanation: after the first accidental success, the cats pressed the switch faster in each subsequent trial. By graphing escape times, he produced a learning curve that was S-shaped, showing that different species learned in the same way but at different speeds. These puzzle-box experiments helped him form his theory of learning.