Major Movements in Psychology


What was Thorndike’s Law of Effect?

Edward Thorndike (1874–1947) was originally a student of Henry James, although his research veered far from James’s fascination with consciousness. As a side note, he was also the author of the Thorndike dictionary. Thorndike turned to the study of chickens while still a graduate student and then expanded his research to observations of cats and dogs. By placing an animal in a puzzle box, or an enclosure with only one means of escape, he could study how the animal learned to escape the box. He observed that animals initially stumble on the escape route (e.g., stepping on a peddle or biting a string) through trial and error. With repeated trials, however, animals take less time to find their way out.

Based on this research, Thorndike formulated two laws of learning. The Law of Effect states that the effect of an action will determine the likelihood that it will be repeated. In other words, if the response generates a satisfying effect (the cat pulls the string and the door opens), the cat is more likely to pull the string again. If the action generates a negative impact, the animal is less likely to repeat the action.

This concept forms the bedrock of B.F. Skinner’s later theory of operant conditioning. Thorndike’s Law of Exercise likewise contributed to theories of associative conditioning. Here he stated that the strength of an association between a response and a stimulus will depend on the number of times they have been paired and the strength of their pairing. Thorndike thus took the associationism of philosophers such as Thomas Hobbes and placed it into a scientific paradigm.


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