Edward Lee Thorndike

(1874 - 1949)

Compiled by Erika Reinemeyer (May 1999)

Thorndike Biography
Time Line

Edward Lee Thorndike was a son of a Methodist minister in Lowell, Massachusetts. He became an American pioneer in comparative psychology and was a typical late 19th century American scientist. He grew up in an age when scientific psychology was establishing its place in academic institutions and attracting college graduates, Thorndike being one of them. He became interested in the field of psychology after reading William Jame's "Principles of Psychology" and after graduating from Weslyan University enrolled at Harvard in order to study under James. His research interest was with children, but his initial study of "mind reading" led to their unavailability for future study. So, he developed projects that examined learning in animals to satisfy requirements for his courses and degree. He completed a study of maze learning in chicks, but for personal reasons, Thorndike did not complete his education at Harvard. Cattell invited him to go to Columbia University where he continued his animal research. He switched from chicks to cats and dogs, and made good use out of his own designed "puzzled boxes." In 1898, he was awarded the doctorate for his thesis, "Animal Intelligence: An Experimental Study of the Associative Processes in Animals", in which he concluded that an experimental approach is the only way to understand learning and established his famous "Law of Effect".

Upon graduation, Thorndike returned to his initial interest, Educational Psychology. In 1899, after a year of unhappy, initial employment at the College for Women of Case Western Reserve in Cleveland, Ohio, he became an instructor in psychology at Teachers College at Columbia University, where he remained for the rest of his career, studying human learning, education, and mental testing.

Edward L. Throndike's pioneer investigations in the fields of human and animal learning are among the most influential in the history of Psychology. In 1912, he was recognized for his accomplishments and elected president of the American Psychological Association. In 1934, the American Association for the Advancement of Science elected Thorndike as the only social scientist to head this professional organization. Thorndike retired in 1939, but worked actively until his death ten years later.


One of Thorndike's major contributions to the study of Psychology was his work with animals. Through long, extensive research with these animals, he constructed devices called "puzzle boxes." This devise is shown in figure 1. This work on animal intelligence used equipment that became both famous and controversial. Thorndike's setup of the puzzle boxes is an example of instrumental conditioning: An animal makes some response, and if it is rewarded, the response is learned. If the response is not rewarded, it gradually disappears. The entire experiment was based on animals being placed into these contraptions, and could only escape from it by making some specific response. Such escape procedures would be pulling a sting or pushing a button.

The way his experiment worked was by placing a hungry cat into the box, then observing its behavior as it tried to escape and obtain some food. puzzle box For the most part, he noticed that the cats obtained the food only by "trial-and-error." On a successive attempt, the mere trial-and-error behavior decreased and the cat would escape quickly. Thorndike studied several cats, and plotted the time it took for them to escape from the puzzle box on successive trials. These learning curves did not suddenly improve, but rather the amount of time the animal spent in the box gradually got to be shortened. From this, the animal did not merely realize what it had to do to escape, but the connection between the animal's situation and the response that gradually freed him was stamped in. With these observations, Thorndike suggested that certain stimuli and responses become connected or dissociated from each other according to his law of effect. He stated, "When particular stimulus-response sequences are followed by pleasure, those responses tend to be ‘stamped in'; responses followed by pain tend to be ‘stamped out'." The final interpretation of the law of effect was the immediate consequence of a mental connection can work back upon it to strengthen it.

This evaluation led Thorndike to conclude that animals learn, solely, by trial and error, or reward and punishment. Thorndike used the cat's behavior in a puzzle box to describe what happens when all beings learn anything. All learning involves the formation of connections, and connections were strengthened according to the law of effect. Intelligence is the ability to form connections and humans are the most evolved animal because they form more connections then any other being. He continued his study with learning by writing his famous Animal Intelligence. In this he argued that we study animal behavior, not animal consciousness, for the ultimate purpose of controlling behavior. Today, he is known for his early animal studies and the founding principle of Instrumental Learning, "The Law of Effect".

Time Line
1874 The birth of Edward Lee Thorndike
1897 Applied for graduate program at Columbia University
1898 Awarded his doctorate
1899 Instructor in Psychology at Teachers College, Columbia
1905 Formalized the Law of Effect
1911 Published "Animal Intelligence"
1912 Elected President of American Psychological Association
1917 One of the first psychologist admitted to the National Academy of Sciences
1921 Ranked #1 as an American Men of Science.
1934 Elected President of the American Association for the Advancement of Science
1939 Retired
1949 Thordike died

Beniafield, John G. A History of Psychology, (Massachusetts: Allyn and Bacon, 1996)
Fancher, Raymond E. Pioneers of Psychology, (New York: W.W. Norton & Company, Inc., 1990)
Leahey, Thomas H. A History of Psychology, (New Jersey: Englewood Cliffs, 1992)

[History Home Page] [Psychology Department Home Page]