  Methodological behaviorism is a normative theory about the scientific conduct of psychology. It claims that psychology should concern itself with the behavior of organisms (human and nonhuman animals). Psychology should not concern itself with mental states or events or with constructing internal information processing accounts of behavior.  According to methodological behaviorism, reference to mental states, such as an animal’s beliefs or desires, adds nothing to what psychology can and should understand about the sources of behavior.  Mental states are private entities which, given the necessary publicity of science, do not form proper objects of empirical study.  Methodological behaviorism is a dominant theme in the writings of John Watson (1878–1958).