Edward Lee Thorndike, was born in Williamsburg, Mass., Aug. 31, 1874, d. Aug. 9, 1949, was a major figure in several fields of psychology: learning theory, applied psychology, and mental measurement. First influenced by William James at Harvard, he studied at Columbia University and taught there from 1909 to 1940. His learning theory, applied to animals and human beings, added the principle of effect (success, pleasure, satisfaction) to Hermann Ebbinghaus's principle of exercise.

Thorndike rid his theories of the mentalism of earlier psychologists and paved the way for the behaviorism of B. F. Skinner and John B. Watson. He published about 500 books and articles, including his thesis Animal Intelligence (1898), Educational Psychology (1903, later in three volumes), and Mental and Social Measurements (1904), and was president of the American Psychological Association. Thorndike's law of effect. Although evidence of classical conditioning was there, E. L. Thorndike did not believe that it was comprehensive because most behavior in the natural environment was not simple enough to be explained by Pavlov's theory.

He conducted an experiment where he put a cat in a cage with a latch on the door and a piece of salmon outside of the cage. After first trying to reach through the cage and then scratching at the bars of the cage, the cat finally hit the latch on the door and the door opened. With the repetition of this experiment, the amount of time and effort spent on the futile activities of reaching and scratching by the cats became less and the releasing of the latch occurred sooner. Thorndike's analysis of this behavior was that the behavior that produced the desired effect became dominant and therefore, occurred faster in the next experiments. He argued that more complicated behavior was influenced by anticipated results, not by a triggering stimulus as Pavlov had supposed. This idea became known as the law of effect, and it provided the basis for Skinner's operant conditioning analysis of behavior (Schwartz & Lacy, 1982, pp. 24-26).