Psychological behaviorism developed during the mid 19th and early 20th centuries. According to Robert H. Wozniak from Bryn Mawr College, behaviorist researchers saw psychology as a natural science that could be broken down into physical processes. They focused on the physical relationships between environment and behavior. Behaviorist philosophy dominated psychology from the 1920s through the 1960s.

Pavlov's Dogs

Ivan Pavlov, a Russian researcher who lived between 1849 and 1936, became famous for his relationship studies between external stimuli and salivation in dogs. Pavlov rang a bell each time he fed his laboratory dogs. The dogs soon began to salivate when the bell was sounded even if there was no food present. He called this response a conditioned reflex. His research was influential in the Behaviorist school of thought.


John Watson published the Behaviorism theory in 1913. His theory indicated that introspection and consciousness were not an important part of psychology; rather, the implicit goal was to control behavior. In his mind there was no difference between human and animal behavior. All behaviors were based on nerve pathways that were conditioned by stimuli and responses.


Edward Thorndike developed the Connectionism theory during the 1920s. Thorndike believed that learning was a result of associations that were formed between a stimulus and response. His Law of Effect stated that if a response to a situation was followed by a positive outcome, the response would become habitual. The Law of Readiness suggested that a person or animal could develop a series of responses to reach a particular goal. He also believed that connections were strengthened if used regularly and weakened if discontinued. He termed this theory the Law of Exercise, according to the Theory into Practice database.

Drive Reduction Theory

Clark Hull's Drive Reduction Theory of the 1940s proposed that humans and animals have a hierarchy of needs that are activated based on drive and stimulation. He suggested that an organism could respond in a number of different ways to a stimulus depending internal conditions such as inhibitions or external factors such as the reward. He believed that the person's or animal's drive or motivation was a key factor in behavior.

Operant Conditioning

Operant conditioning methods are based on Watson's behaviorist theories. They are still widely used in classroom-management techniques and clinical settings as a method of controlling behavior. During the 1950s, B.F. Skinner theorized that learning was the result of a change of behavior that occurred as a response to stimuli in the environment. He believed that reinforcement, which is any motivator that elicits the desired response, was a key element in operant conditioning. He felt that behaviors that were positively reinforced through praise, treats or good grades would continue, while negative behaviors that were unrewarded would diminish.