Behaviorism

An approach to psychology that emphasizes the study of objectively observable behavior rather than inner mental experiences. Behaviorists stress the role of the environment as a fundamental shaper of human and animal behavior. Behaviorist use behavior modification to re-shape the behavior of subjects.

For more information, see behavioral medicine and behavior modification.

About Behaviorism
If you want to learn about behaviorism this is the first book you should read. By B. F. Skinner, the father of behaviorism.