Edward Thorndike

Edward Lee Thorndike was a highly influential American psychologist. He spent nearly his entire professional life at Teachers College, Columbia University. His research into how living things learn helped create the field of educational psychology. He is most famous for developing the theory of connectionism. This theory explains how different mental processes and behaviors become linked together. A 2002 survey ranked him as the ninth-most cited psychologist of the 20th century.

Thorndike focused heavily on comparative psychology, which is the study of how different species learn. He wanted to know if animals learned through observation or through direct experience. To test this, he designed special tools called puzzle boxes. These boxes were roughly 20 inches long, 15 inches wide, and 12 inches tall. Each box had a door connected to a weight by a string and a pulley. Inside the box, there was a lever or a button. When an animal pressed the lever, the weight lifted and the door opened.

Thorndike primarily used cats for these experiments. He observed that the cats would initially wander restlessly and meow inside the boxes. Eventually, a cat would accidentally step on a lever or button. This would cause the door to open and allow the cat to escape. Once escaped, the cat was given a reward, which was usually food. Thorndike found that the cats did not learn by watching other animals escape. Instead, they learned through a process called trial and error. They tried many different movements until they found the one that worked.

To track this progress, Thorndike used a tool called a learning curve. This is a graph that plots the time it takes to complete a task over many attempts. He noticed that the cats' escape times did not drop suddenly. Instead, the times decreased gradually as the cats practiced. This resulted in a graph with an S-shape. This gradual change proved that the cats were not using sudden "insight" to solve problems. They were instead building connections through repeated actions and rewards. This specific type of learning is known as instrumental learning.

From these experiments, Thorndike developed several important scientific laws. One major principle is the law of effect. This law states that behaviors followed by a "satisfying state of affairs" are likely to be repeated. Conversely, behaviors followed by an "annoying state of affairs" are likely to weaken. He also proposed the law of exercise. This law has two parts: the law of use and the law of disuse. The law of use says that frequent use strengthens a connection. The law of disuse says that a lack of use weakens it.

Thorndike also identified different types of intellectual development. He categorized intelligence into three main areas. The first is abstract intelligence, which involves processing different concepts. The second is mechanical intelligence, which is the ability to handle physical objects. The third is social intelligence, which involves human interaction. He also studied the "identical elements theory of transfer." This theory suggests that learning in one situation helps in another only if the two situations are similar. The more similar they are, the more information transfers from one to the other.

Thorndike's career was marked by many significant roles and achievements. He served as the president of the American Psychological Association in 1912. In 1937, he became the second president of the Psychometric Society. He also applied his expertise to the United States Army during World War I. He helped develop the Army Beta test to evaluate recruits who were illiterate or did not speak English. His work on mental testing and industrial problems helped shape how we measure human ability today.

Thorndike was born in Williamsburg, Massachusetts. His father, Edward R. Thorndike, was a Methodist minister. Edward earned his degrees from Wesleyan University and Harvard University. He completed his PhD at Columbia University in 1898 under James McKeen Cattell. He married Elizabeth Moulton in 1900, and they had five children. His brothers also became notable scholars in fields like science history and English literature. Thorndike's legacy remains a foundation for modern behavior analysis and classroom instruction.