Some of the major schools of thought in the field of psychology are structuralism, functionalism, behaviorism and cognitivism. The history of modern psychology can be said to have begun around 1879, when one of the first laboratories devoted exclusively to psychological study was set up by Wilhelm Wundt in Leipzig, Germany. Wundt's interest was in studying the basic components of mental processes and he is viewed as having laid the foundation for the first major school of psychology, which is structuralism.
The next major school to develop was functionalism. Three American psychologists were instrumental in contributing to its beginnings: G. Stanley Hall, James M. Cattell and William James. Functionalism differed from structuralism in its focus on how the mind works rather than concentrating on its anatomy and structure. James played a significant role in steering psychology away from the structuralist view held by Edward Titchener, who was strongly opposed to functionalism. James' 1890 book, "The Principles of Psychology," laid the groundwork for many of the issues that psychologists would explore in the 20th century.
John B. Watson took a radical turn from the established schools of thought in 1913 by introducing the concept of behaviorism. The new school of thought became the dominant view of psychology during the 1950s. The focus was on issues that were objective and fully observable and it dealt primarily with behaviors. Behaviorism was expanded by the large body of work B.F. Skinner conducted in the area of environmental stimulus and conditioned response.
Cognitivism developed as a school of thought that was in reaction to the behaviorist concepts of stimulus, response and conditioning. Cognitive psychology is focused on how knowledge is used and formed, and it deals with a wider array of processes such as learning, decision making, creativity and language.