Research on purpose is aimed at identifying the perceptual variables that a system is controlling when it is carrying out various purposeful behaviors. The basic methodology used to do this kind of research is the test for controlled variable or TCV, which involves testing hypotheses about the perceptual variables the organism is controlling. These hypotheses are formal definitions of the perception under control. They are tested by looking for lack of an expected effect of disturbances to the hypothesized controlled variable. The TCV has to start with the formulation of hypotheses about the variables around which behavior is organized. The researcher has to be able to look at what an organism is doing and come up with definitions of the variables it is controlling – definitions that are precise enough so that it is possible to predict how disturbances would affect these variables if they were not being controlled.

Application of control theory to predict human behavior is largely based on Powers’s (1973) work, which can be traced indirectly through Carver and Scheier’s (1982) self-regulation theory and directly through interventions in areas of child development, mental health, education, and organizational psychology. Control theory proposes that behavior changes from moment to moment to keep perceived aspects of the self and world close to desired reference values – a person’s goals, standards, or ideals. Control is achieved through actions that help the individual meet their standards. Individuals can change their behavior to either cooperate or conflict with their attempts to control the same perceived aspect of the world (e.g., money, food, alcohol, drugs, medicine). Control theory is a “building blocks” theory from which working models can be built and tested and sets a new standard for empirical testing of psychological theory. This chapter reviews the evidence for each component of control theory. It describes how behavior change emerges for many different reasons, each of which can be modeled and tested. The chapter also questions whether “behavior change” itself is an appropriate, or efficient, objective. Finally, the chapter summarizes evidence for behavior change interventions informed by control theory and provides suggestions for future research and interventions using the theory.