Behaviorism (or behaviourism) is a systematic approach to understanding the behavior of humans and other animals. It assumes that all behaviors are either  produced by a response to certain stimuli in the environment, or a consequence of that individual’s history, including especially reinforcement and punishment, together with the individual’s current motivational state and controlling stimuli. Although behaviorists generally accept the important role of  in determining behavior, they focus primarily on environmental factors.

Behaviorism combines elements of philosophy, methodology, and psychological theory. It emerged in the late nineteenth century as a reaction to  and other traditional forms of psychology, which often had difficulty making predictions that could be tested experimentally. The earliest derivatives of Behaviorism can be traced back to the late 19th century where  pioneered the , a process that involved strengthening or weakening behavior through the use of  and .

During the first half of the twentieth century,  devised , which rejected  and sought to understand behavior by only measuring observable behaviors and events. It was not until the 1930s that  suggested that private events—including thoughts and feelings—should be subjected to the same controlling variables as observable behavior, which became the basis for his philosophy called “.” While Watson and  investigated the stimulus-response procedures of , Skinner assessed the controlling nature of consequences and also its potential effect on the ; the technique became known as .

Skinner’s radical behaviorism has been highly successful experimentally, revealing new phenomena with new methods, but Skinner’s dismissal of theory limited its development. Theoretical behaviorism recognized that a historical system, an organism, has a state as well as sensitivity to stimuli and the ability to emit responses. Indeed, Skinner himself acknowledged the possibility of what he called “latent” responses in humans, even though he neglected to extend this idea to rats and pigeons. Latent responses constitute a repertoire, from which operant reinforcement can select.