Behavioural change theories are attempts to explain why behaviours change. These theories cite environmental, personal, and behavioural characteristics as the major factors in behavioural determination. In recent years, there has been increased interest in the application of these theories in the areas of health, education, criminology, energy and international development with the hope that understanding behavioural change will improve the services offered in these areas. Some scholars have recently introduced a distinction between models of behavior and theories of change. Whereas models of behavior are more diagnostic and geared towards understanding the psychological factors that explain or predict a specific behavior, theories of change are more process-oriented and generally aimed at changing a given behavior. Thus, from this perspective, understanding and changing behavior are two separate but complementary lines of scientific investigation.
Each behavioural change theory or model focuses on different factors in attempting to explain behavioural change. Of the many that exist, the most prevalent are the learning theories, social cognitive theory, theories of reasoned action and planned behaviour, transtheoretical model and the health action process approach. Research has also been conducted regarding specific elements of these theories, especially elements like self-efficacy that are common to several of the theories.
Self-efficacy is an individual's impression of their own ability to perform a demanding or challenging task such as facing an exam or undergoing surgery. This impression is based upon factors like the individual's prior success in the task or in related tasks, the individual's physiological state, and outside sources of persuasion. Self-efficacy is thought to be predictive of the amount of effort an individual will expend in initiating and maintaining a behavioural change, so although self-efficacy is not a behavioural change theory per se, it is an important element of many of the theories, including the health belief model, the theory of planned behaviour and the health action process approach.