Martin S. Hagger1,2,3,4 and Amanda L. Rebar4
1Health Psychology and Behavioral Medicine Research Group, School of Psychology and Speech Pathology, Faculty of Health Sciences, Curtin University, Perth, WA, Australia
2Faculty of Sport and Health Sciences, University of Jyväskylä, Jyväskylä, Finland
3School of Applied Psychology and Menzies Health Institute Queensland, Behavioural Bases for Health, Griffith University, Brisbane, QLD, Australia
4Centre for Physical Activity Studies, School of Human, Health and Social Sciences, Central Queensland University, Rockhampton, QLD, Australia
“Healthy habits” are a frequent topic of conversation in everyday life. People want to “get into the habit” of exercise or healthy eating or “break bad habits” like smoking or drinking too much alcohol. These frequent references to habit tacitly acknowledge that good habits are difficult to form and bad habits difficult to stop. Psychological research indicates that habits have a strong “automatic” or “implicit” component. That is, individuals tend to perform habits with relatively little conscious thought or effort. The propensity for actions to be controlled automatically is an extremely adaptive human function, as it means that mundane actions can be carried out with little cognitive effort, which “frees up” cognitive “space” for processing higher‐order goals and actions. Health behaviors that are habitual are, therefore, regulated and enacted in an efficient and effective manner. However, the same system can automate behaviors that are detrimental to health, making them difficult to change. Health psychologists are interested in studying habit to understand the processes that lead to habit formation and perhaps develop means to change habits by promoting healthy habits and breaking unhealthy ones.
Formally, habit is defined as “a process by which a stimulus automatically generates an impulse towards action, based on learned stimulus‐response associations” (Gardner, 2015, p. 4). In contradiction to the colloquial use of the term, habit is not a behavior, but rather a psychological or cognitive determinant of behavior. Habit formation is the process by which regulation of health behavior shifts from being under conscious, deliberative control to being regulated largely by nonconscious, automatic processes (Gardner, 2015; Sheeran, Gollwitzer, & Bargh, 2013; Wood & Neal, 2009). When a person frequently and consistently enacts a health behavior in the context of a behaviorally relevant cue or—so as to form a strong mental association between the cue and behavior—a habit is formed. Research has demonstrated that the strength of people's habits is a strong influence on their health‐related behaviors and this effect is independent of conscious regulation such as goal setting, planning, or intentions (Conroy, Maher, Elavsky, Hyde, & Doerksen, 2008; Gardner, de Bruijn, & Lally, 2011). Exciting advancements in the study of health‐related habits demonstrate strategies that people may use to break unhealthy habits and the potential for targeting habit formation as a strategy for promoting maintainable healthy behaviors (e.g., Lally & Gardner, 2013; Webb, Sheeran, & Luszczynska, 2009).
Consideration for the role of habits in the study of health behaviors has been a relatively recent advancement, and as a result, most studies have incorporated a measure of habit1 as a separate correlate of health behavior alongside psychological factors from conventional social cognitive theories of behavior change (Biddle, Hagger, Chatzisarantis, & Lippke, 2007). This research has been further advanced through the application of dual‐process theories, which contend that behavior is a function of both nonconscious (e.g., habit) and conscious processes (e.g., goals, deliberation, attitudes, and values; Strack & Deutsch, 2004 #1742;Hagger, 2016 #8248). For example, Rothman, Sheeran, and Wood (2009) present a model for understanding which conscious and nonconscious processes are important for adoption versus maintenance of health‐related behaviors and outline how habits likely play a key role in the maintenance of health‐related behaviors. Similarly, Rhodes and de Bruijn propose habit as a key factor involved in the control of actions in health contexts (i.e., translating intentions into action; Rhodes & de Bruijn, 2013).
The common theme of dual‐process models is that health behaviors can be predominantly controlled by either reflective consideration of the action (e.g., weighing up the advantages, disadvantages, consequences, and barriers with respect to the behavior) or impulsive processes that lead to automatic behavioral enactment. The influences from both types of regulatory systems are supported by evidence from neuroscience that shows that activity in the fronto‐parietal and cingulo‐opercular networks is associated with deliberative actions, whereas activity in subcortical areas of the mesolimbic reward system such as the nucleus accumbens is associated with habitual behaviors (Rebar, Loftus, & Hagger, 2015).
Given that habitual behaviors are rapid, efficient, and free of conscious control and occur beyond an individual's awareness, they tend to be the “dominant” response when individuals are presented with cues that initiate their action (Gardner, 2015; Verplanken & Aarts, 1999). For an individual to change or break a habit, therefore, they must consciously monitor their environment for the habit‐triggering cue and, on its presentation, actively inhibit the automatic behavioral response. Without sufficient deliberative control over cues and associated automatic responses, referred to as self‐regulation, the dominant response is likely to pervade in situations where the cue is presented. Even when individuals identify health goals and form plans to achieve these goals, habits may compete with these, and, given that the habitual pathways to action tend to predominate, they may lead to failure to carry out the good intentions.
Research has demonstrated that habit is associated with a number of health‐related behaviors (e.g., Gardner et al., 2011; Hyde, Elavsky, Doerksen, & Conroy, 2012; Webb et al., 2009). Research has also examined the factors that determine whether health behavior is likely to be under habitual control or controlled by more deliberative, conscious processes. For example, an increasing body of evidence is demonstrating that intentions to engage in physical activity or eating healthily are better predictors of behavior for people if habits of these behaviors are weaker (Gardner et al., 2011; Rhodes & de Bruijn, 2013), and more recent evidence suggests this could be a time‐dependent process in that people act on their habits unless they make particularly strong intentions to engage in a counter‐habitual behavior on a certain day (Rebar, Elavsky, Maher, Doerksen, & Conroy, 2014). Furthermore, research has shown that individuals find it difficult to accurately recall habitual actions because such actions do not depend on awareness or conscious control (Hyde et al., 2012).
Research is also beginning to provide insight into the process by which habits form. For example, research has shown that habit formation requires more than mere repetition of the behavior (Hagger, Rebar, Mullan, Lipp, & Chatzisarantis, 2015; Lally & Gardner, 2013) and that the habit formation process is different for each person, but typically occurs quickly at first and gradually slows when a person nearly reaches full habit development (Lally & Gardner, 2013). Factors that have been shown to determine the formation of habits are planning and behavior enactment, strong cue–behavior implicit associations, or increasing the intrinsic value of the behavior by providing incentives or rewards (Lally & Gardner, 2013).
In addition, research is starting to emerge on how the formation of habits can be targeted within interventions aimed at promoting healthy habits (Gardner, Lally, & Wardle, 2012; Lally & Gardner, 2013). Habits form through repetition of behavior in a specific context, so the habitual response becomes strongly associated with a triggering cue, making the habitual response the strong default and alternative behavioral choices less salient (Wood & Neal, 2009). Simple intervention strategies to promote frequent and consistent performance of the desired habitual behavior in the context of an accessible cue (e.g., in the same manner, at the same time of day or part of a daily routine, in the same place) through a list of tips, messages via emails and SMS, or face‐to‐face training have shown not only to enhance health behavior but also to make the behavior more habitual. Additionally, incorporating “boosters” following intervention completion focused on action planning, self‐efficacy, and satisfaction behavioral outcomes may serve to maintain intervention effects on habit.
Promotion of a healthy lifestyle often requires a combination of forming stronger healthy behavior habits (e.g., healthy eating, physical activity, medication adherence) and breaking habits for unhealthy behaviors (e.g., smoking, snack eating, sedentary behavior). Research has demonstrated that effective breaking of “bad” habits requires goal setting, cue monitoring, and effortful self‐regulation (Lally & Gardner, 2013). Such efforts can be quite taxing, and engaging in effortful control over habits may be counterproductive, as it may lead to cognitive fatigue and reduced capacity for self‐control, leaving people susceptible to temptations that cue up unwanted habitual responses (Hagger & Chatzisarantis, 2014). An option for reducing habitual unhealthy behaviors may be to avoid or minimize accessibility or presence of triggering cues by, for example, moving locations or to weaken the mental cue–response association through training techniques such as evaluative conditioning (Allom, Mullan, & Hagger, 2016).
A number of priorities for future research on habits in the context of health‐related behavior have been identified. Researchers are beginning to differentiate between habitual instigation (i.e., the initiation of a behavior) and execution (i.e., the movement through the sequence of the behaviors) (Gardner, Phillips, & Judah, 2016). A proposed model is that in early stages of taking up a new behavior, behavioral initiation is predominantly controlled by more deliberative, reflective processes in which an individual weighs up the benefits and detriments of the behavior in a given context and makes decisions on whether or not to act accordingly. This process becomes more “automated” or habitual over time with repeated decisions to engage in behavior raising the possibility of links being made between the behavior and the decision‐making process and external or internal cues. However, while behavioral initiation may become more automated, more complex processes involved in executing the behavior may not become automatic as they require elaborate planning and deliberation. Such distinctions may provide a comprehensive framework for promoting complex health‐related behaviors that involve more than a single act (e.g., physical activity, eating, sedentary behavior).
Another avenue of research, that is, essential for advancing theory of health‐related habit is to understand how the influence of habit compares to and interacts with that of other nonconscious regulatory processes such as automatic evaluations (e.g., implicit attitudes) or primed motivation (Conroy et al., 2008; Hagger, 2016; Sheeran et al., 2013). Most research on health‐related habit has been studied alongside consciously controlled psychological constructs, but this largely downplays and likely simplifies the impact that other nonconscious processes have on health behaviors. Researchers should consider merging what have, to this point, been largely separate avenues of research on habit and these other nonconscious regulatory processes that are not reliant on learning.
Finally, the role of implicitly presented cues in developing habitual responses should be explored. Research examining the potential for environmental contingencies, structural changes, and means to prompt behaviors (e.g., posters and advertisements) to promote healthy behavior, often beyond an individual's conscious awareness, has shown promise (Hagger, 2016). However, the research on the mechanisms and processes by which these contingencies affect behavior and assist in the development of habits is relatively sparse. Future research should explore the longevity of such prompts in promoting lasting behavior change and whether these develop into habits.
A health behavior is considered habitual if it is predominantly determined by “automatic” or “nonconscious” processes. Habitual behaviors tend to be developed over time through repetition and reward or reinforcement by external or internal contingencies or reinforcing agents. Habits may be represented schematically in memory and activated by the presentation of cues or prompts in the environment with which enactment of the habituated behavior is associated. As links between prompts and habitual behaviors tend to be very strong, changing habitual behaviors that are detrimental to health is challenging. However, the strong links also present an opportunity for interventionists as they provide a means to develop healthy habits and lasting behavior change. Research on habits has provided insight into the processes by which habits impact health behavior and an evidence base on which to develop interventions to break or change habits. Breaking bad habits requires effortful, goal‐directed behavior, and self‐regulatory skills such as goal setting and cue monitoring have been shown to be effective strategies to break health behaviors. Future research should seek to examine the role of priming interventions, implicit constructs, and the distinction between initiation and execution of health behavior to provide further insight into the processes that lead to health behavior.
Martin S. Hagger is John Curtin Distinguished Professor in the School of Psychology and Speech Pathology at Curtin University, Australia. His research applies social cognitive and motivational theories to understand and to intervene and change diverse health behaviors such as physical activity, healthy eating, smoking cessation, alcohol reduction, and medication adherence. He is also at the forefront of theory development and has contributed to the advancement of social psychological theory including theory integration and self‐control.
Amanda L. Rebar is senior lecturer in the Centre for Physical Activity Studies in the School of Health, Medical and Applied Sciences at Central Queensland University, Australia. Her research interests include physical activity motivation—specifically automatic regulation of physical activity (e.g., habits, automatic evaluations) and the mental health benefits of physical activity. She is also interested in structural equation modeling, hierarchical linear modeling, and the open‐source data analysis program, R.