Abstract
Many of the most pressing societal issues—e.g., health, illness, and associated costs; climate change—are rooted in behavior. Even small changes to everyday behaviors can bring considerable benefits. Many people successfully adopt new behaviors but fail to maintain them over time. This problem has inspired interest in habit. Within psychology, habitual behaviors are defined as actions triggered automatically when people encounter situations in which they have consistently done them in the past. Repeating behavior in the same context reinforces mental associations between the context and behavior. Habit is said to have formed when exposure to the context non-consciously activates the association, which in turn elicits an urge to act, influencing behavior with minimal conscious forethought. As an initially goal-directed behavior becomes habitual, control over behavior is transferred from a reasoned, reflective processing system, which elicits behavior relatively slowly based on conscious motivation, to an impulsive system, which elicits behavior rapidly and efficiently, based on learned context-behavior associations. Habitual behaviors thus become detached from conscious motivational processes. Spurred by development of self-report habit measures, studies have modeled the relationship between behavioral repetition and the strengthening of habit, showing that habit is characterized by initially rapid growth, which decelerates until a plateau is reached. Theories propose that habit has two effects on behavior in the associated context: habit will prompt frequent performance, and will override motivational tendencies in doing so, unless self-control is particularly strong in that moment. People may therefore continue to perform a habitual action even when they lack motivation. These characteristics have generated interest in the potential for habit to support long-term adoption of new behaviors. People often fail to maintain behavior changes because they lose motivation, but if people were to form habits for new behaviors, they should in theory continue to perform them despite losing motivation. This has prompted calls for interventions to move beyond merely promoting new behaviors, toward advocating context-dependent habitual performances. Some have also argued that habit formation may be fruitful for stopping unwanted behaviors, because new, “good” habits can be directly substituted for existing “bad” habits. Realistically, habit formation is not a viable standalone behavior change technique, as it requires that people first adopt a new behavior, which through repetition will become habitual. The promotion of context-dependent repetition should complement techniques that reinforce the motivation and action control required for behavioral initiation and maintenance prior to habit forming. Real-world behavior change interventions based on these principles have been found to be acceptable and appealing, and show promise for changing behavior, though few have used long-term follow-up periods. This entry highlights leading work in the application of habit formation to behavior change interventions, drawing on the most methodologically and conceptually rigorous empirical research available. Most of the development and application of habit theory to real-world social contexts has been undertaken in health and pro-environmental domains. This entry thus focuses most heavily on these domains, but the principles outlined are thought to be applicable across behaviors and settings.