Behavioral psychology is a major paradigm of psychology that focuses on describing organism behavior as a product of environmental inputs. Behaviorist view the mind as a black box and do not believe that it can be defined or investigated with the scientific method. Behavioral psychology views all organism behavior as an output derived purely from the input of the environment.
This branch of psychology was thought up by James B. Watson. James B. Watson in 1916 he started observing and making connections between animals and humans. His most famous experiment was conducted in the winter of 1919 and 1920 with a baby known as Albert B. Watson and his assistant gave Albert a white lab rat; he was unafraid and tried to touch the rat. He was afraid, however, when they clanged metal with a hammer just behind his head, and he cried. A few months later, when Albert was 11 months old, they again gave him the rat, but this time just as he touched it, the metal clang sounded behind his head. That made him cry. This was repeated several times over a few weeks. Before long just the sight of the rat made Albert cry and try to crawl away. In fact, any furry item a stuffed toy, a fur coat, even a Santa Claus mask made Albert cry and be afraid. The most well known area of investigation is the role of classical conditioning and instrumental learning. The work of Ivan Pavlov at the start of the 20th century demonstrated that an unrelated stimulus, such as a bell, could elicit a reflexive response, such as a salivation, if the bell had been paired repeatedly with a stimulus that naturally creates that response, such as the presentation of food. The number of pairings needed and the size of the response could be mathematically described and offered hope that a science of psychology could emerge that had the mathematical properties of other sciences such as physics. B.F. Skinner was a major proponent of the paradigm and developed the concept of instrumental learning, where complex behavior could be learned by rewarding small increments of behavior. Skinner believed all behavior, including that of humans, could be described completely by environmental inputs.
In modern research there are few die hard behaviorist, the cognitive revolution showed to many that it was both possible and necessary to describe the minds role in behavior.