Dr Phillippa Lally

Habitual actions are elicited automatically in associated settings, bypassing conscious motivation. This has prompted interest in habit formation as a mechanism for sustaining behaviour change when conscious motivation erodes. Promoting habit depends on understanding how habit develops. This chapter reviews theory and evidence around the habit formation process. First, we describe the few, recent studies that have explicitly sought to study habit development for meaningful activities in humans. Next, we outline a framework for understanding the habit formation process, and narratively review evidence regarding the factors that may directly facilitate or impede habit development, generating hypotheses for future studies. We offer practical suggestions for optimal modelling of habit formation and its determinants.

Advances in understanding how habit forms can help people change their behaviour in ways that make them happier and healthier. Making behaviour habitual, such that people automatically act in associated contexts due to learned context-response associations, offers a mechanism for maintaining new, desirable behaviours even when conscious motivation wanes. This has prompted interest in understanding how habit forms in the real world. To reliably inform intervention design, habit formation studies must be conceptually and methodologically sound. This paper proposes methodological criteria for studies tracking real-world habit formation, or potential moderators of the effect of repetition on formation. A narrative review of habit theory was undertaken to extract essential and desirable criteria for modelling how habit forms in naturalistic settings, and factors that influence the relationship between repetition and formation. Next, a methodological review identified exemplary real-world habit formation studies according to these criteria. Fourteen methodological criteria, capturing study design (four criteria), measurement (six criteria), and analysis and interpretation (four criteria), were derived from the narrative review. Five extant studies were found to meet our criteria. Adherence to these criteria should increase the likelihood that studies will offer revealing conclusions about how habits develop in real-world settings.

Maintaining weight loss requires long-term behaviour change. Theory and evidence around habitual behaviour ? i.e., action triggered by impulses that are automatically activated upon exposure to cues, due to learned cueaction associations ? can aid development of interventions to support weight loss maintenance. Specifically, weight loss is more likely to be sustained where people develop new habits that support weight management, and break old habits that may undermine such efforts. Interventions seeking to break ?bad? weight-related habits have focused on inhibiting unwanted impulses or avoiding cues. This paper draws attention to the possibility that while such approaches may discontinue habitual behaviour, underlying habit associations may remain. We use evidence from existing qualitative studies to demonstrate that, left unchecked, unwanted habit associations can render people prone to lapsing into old patterns of unhealthy behaviours when motivation or willpower is momentarily weakened, or when returning to familiar settings following temporarily discontinued exposure. We highlight six behaviour change techniques especially suited to disrupting habit associations, but show that these techniques have been underused in weight loss maintenance interventions to date. We call for intervention developers and practitioners to adopt techniques conducive to forming new habit associations to directly override old habits, and to use the persistence of unwanted habit associations as a potential indicator of longterm weight loss intervention effectiveness.

The COVID-19 pandemic saw promotion of novel virus transmission-reduction behaviours, and discouragement of familiar transmission-conducive behaviours. Understanding changes in the automatic nature of such behaviours is important, because habitual behaviours may be more easily reactivated in future outbreaks and disrupting old habits may discontinue unwanted behaviours. A repeated-measures, multi-national design tracked virus-transmission habits and behaviour fortnightly over six months (Apr-Sept 2020) among 517 participants (age M = 42 ± 16y, 79% female). Within-participant habit trajectories across all timepoints, and engagement in transmission-reduction behaviours (handwashing when entering home; handwashing with soap for 20 seconds; physical distancing) and transmission-conducive behaviours (coughing/sneezing into hands; making physical contact) summed over the final two timepoints. Three habit trajectory types were observed. Habits that remained strong ('stable strong habit') and habits that strengthened ('habit formation') were most common for transmission-reduction behaviours. Erosion of initially strong habits ('habit degradation') was most common for transmission-conducive behaviours. Regression analyses showed 'habit formation' and 'stable strong habit' trajectories were associated with greater behavioural engagement at later timepoints. Participants typically maintained or formed transmission-reduction habits, which encouraged later performance, and degraded transmission-conducive habits, which decreased performance. Findings suggest COVID-19-preventive habits may be recoverable in future virus outbreaks.

A vegan diet, which excludes all animal-derived products, has been associated with some improvements in health, while also conferring environmental benefits. Understanding the psychological determinants of successfully switching to a vegan diet will help to inform the design of interventions supporting long-term dietary change. Studies to date have tended to focus on reasoned motives underlying the decision to initiate such a dietary shift. Yet, focusing on reasons for switching may overlook the importance of a broader range of psychological factors that may help or hinder attempts to maintain a vegan diet. This qualitative interview study, the timing of which coincided with UK Covid-19 lockdowns, documented experiences of 20 young adults (17 female; mean age 22y) who attempted to adopt a vegan diet in the past nine months and had or had not successfully maintained this change. Reflexive Thematic Analysis identified five themes surrounding initiation and maintenance. A theme of ‘motives, expectations and cues to switching’ showed that switching was motivated by ethical or health concerns, and cued by Veganuary, lockdown or health issues. ‘The effortfulness of switching’ captured experiences of the perceived burden imposed by adhering to the diet due to, for example, a perceived lack of accessible vegan options. The ‘flexibility of dietary rules’ theme showed that many found the ‘no animal products’ rule clear but restrictive, so allowed themselves occasional non-meat animal products. ‘Social acceptability concerns’ captured the importance of acceptance from vegan and non-vegan family and friends, and ‘satisfaction with the switch’ described the perceived benefits that sustained maintenance for many. Our findings suggest that interventions should seek to support people to overcome potentially unforeseen practical and social challenges to adhering to a vegan diet.

Habit formation is thought to aid maintenance of physical activity, but little research is available into determinants of habit strength aside from repeated performance. Previous work has shown that intrinsically motivated physical activity, underpinned by inherent satisfaction derived from activity, is more likely to be sustained. We explored whether this might reflect a tendency for self-determined activity to become more strongly habitual. A sample of 192 adults aged 18-30 completed measures of motivational regulation, intention, behaviour, and habit strength. Results showed that self-determined regulation interacted with past behaviour in predicting habit strength: prior action was more predictive of habit strength among more autonomously motivated participants. There was an unexpected direct effect of self-determined regulation on habit strength, independently of past behaviour. Findings offer possible directions for future habit formation work.

Habits are automatic behavioural responses to environmental cues, thought to develop through repetition of behaviour in consistent contexts. When habit is strong, deliberate intentions have been shown to have a reduced influence on behaviour. The habit concept may provide a mechanism for establishing new behaviours, and so healthy habit formation is a desired outcome for many interventions. Habits also however represent a potential challenge for changing ingrained unhealthy behaviours, which may be resistant to motivational shifts. This review aims to provide intervention developers with tools to help establish target behaviours as habits, based on theoretical and empirical insights. We discuss evidence-based techniques for forming new healthy habits and breaking existing unhealthy habits. To promote habit formation we focus on strategies to initiate a new behaviour, support context-dependent repetition of this behaviour, and facilitate the development of automaticity. We discuss techniques for disrupting existing unwanted habits, which relate to restructuring the personal environment and enabling alternative responses to situational cues.

Physical distancing remains an important initiative to curb COVID-19, and virus transmission more broadly. This exploratory study investigated how physical distancing behaviour changed during the COVID-19 pandemic and whether it was associated with identity with virus transmission avoidance and physical distancing habit strength. In a longitudinal, multinational study with fortnightly repeated-assessments, associations and moderation effects were considered for both overall (person-level means) and occasion-specific deviations in habit and identity. Participants (N=586, M age = 42, 79% female) self-reported physical distancing behavioural frequency, physical distancing habit strength, and identity with avoiding virus transmission. Physical distancing followed a cubic trajectory, with initial high engagement decreasing rapidly before increasing again near study end. Physical distancing was associated with both overall and occasion-specific virus transmission avoidant identity and physical distancing habit strength. People with strong virus transmission avoidant identity engaged in physical distancing frequently regardless of fluctuations in habit strength. However, for those with weaker virus transmission avoidant identity, physical distancing was strongly aligned with fluctuations in habit strength. To enhance engagement in physical distancing, public health messaging might fruitfully target greater or more salient virus-transmission avoidance identity, and stronger physical distancing habit.

Background Health behaviour models typically neglect habitual action. The Self-Report Habit Index (SRHI) permits synthesis of evidence of the influence of habit on behaviour. Purpose The purpose of this study is to review evidence around mean habit strength, habit–behaviour correlations, and habit × intention interactions, from applications of the SRHI to dietary, physical activity, and active travel behaviour. Method Electronic database searches identified 126 potentially relevant papers. Twenty-two papers (21 datasets) passed eligibility screening. Mean scores and correlations were meta-analysed using fixed, random and mixed effects, and interactions were synthesised via narrative review. Results Twenty-three habit–behaviour correlations and nine habit × intention interaction tests were found. Typical habit strength was located around the SRHI midpoint. Weighted habit–behaviour effects were medium-to-strong (fixed: r+ = 0.44; random: r+ = 0.46). Eight tests found that habit moderated the intention–behaviour relation. Conclusion More comprehensive understanding of nutrition and activity behaviours will be achieved by accounting for habitual responses to contextual cues.

Habitual behaviours are triggered automatically, with little conscious forethought. Theory suggests that making healthy behaviours habitual, and breaking the habits that underpin many ingrained unhealthy behaviours, promotes long-term behaviour change. This has prompted interest in incorporating habit formation and disruption strategies into behaviour change interventions. Yet, notable research gaps limit understanding of how to harness habit to change real-world behaviours. Discussions among health psychology researchers and practitioners, at the 2019 European Health Psychology Society 'Synergy Expert Meeting', generated pertinent questions to guide further research into habit and health behaviour. In line with the four topics discussed at the meeting, 21 questions were identified, concerning: how habit manifests in health behaviour (3 questions); how to form healthy habits (5 questions); how to break unhealthy habits (4 questions); and how to develop and evaluate habit-based behaviour change interventions (9 questions). While our questions transcend research contexts, accumulating knowledge across studies of specific health behaviours, settings, and populations will build a broader understanding of habit change principles and how they may be embedded into interventions. We encourage researchers and practitioners to prioritise these questions, to further theory and evidence around how to create long-lasting health behaviour change.

Objectives. Repeated action can lead to the formation of habits and identification as the kind of person that performs the behaviour. This has led to the suggestion that identity-relevance is a facet of habit. This study explores conceptual overlap between habit and identity, and examines where the two constructs fit into an extended Theory of Planned Behaviour (TPB) model of binge-drinking among university students. Design. Prospective, questionnaire-based correlational design. Methods. A total of 167 UK university students completed baseline measures of past behaviour, self-identity, the Self-Report Habit Index (SRHI), and TPB constructs. One week later, 128 participants completed a follow-up behaviour measure. Results. Factor analyses of the SRHI and four identity items revealed two correlated but distinct factors, relating to habit and identity, respectively. Hierarchical regression analyses of intention and behaviour showed that identity contributed over and above TPB constructs to the prediction of intention, whereas habit predicted behaviour directly, and interacted with intentions in predicting behaviour. Habits unexpectedly strengthened the intentionbehaviour relation, such that strong intenders were more likely to binge-drink where they also had strong habits. Conclusions. Identity and habit are conceptually discrete and impact differently on binge-drinking. Findings have implications for habit theory and measurement. Recommendations for student alcohol consumption reduction initiatives are offered.

Habitual behaviours are elicited when a familiar context activates cue-behaviour associations that have been learned through previous performance. A core hypothesis within habit theory is that, by virtue of its automaticity, habit weakens the impact of intention on action, such that in facilitating conditions, action will be guided more by habit than momentary intentions. This has led to recommendations that habit formation be harnessed as a mechanism for sustaining desirable behaviour over time, when people would otherwise relapse due to loss of motivation. This article reviews theory and evidence around the hypothesized interaction between habit and intention as determinants of behaviour. We first qualify the hypothesis by clarifying that it pertains only to determinants of the instigation of action, rather than execution. Next, drawing on a systematic review of 52 behaviour-prediction studies, we highlight mixed empirical support for the interaction. We argue that ostensibly inconsistent findings can be reconciled by recognizing the distinction between the direction and strength of intention, and identifying the "facilitating conditions" that may determine the relative influence of habit and intention on behaviour. Evidence demonstrates that when self-control is diminished, people act habitually regardless of intention direction or strength. When people possess self-control, habits can help people to act on favourable but weakened intentions, but intentions that oppose habitual tendencies can override habitual influence. This has important implications for behaviour change: even if habit has formed, a minimal level of favourable conscious motivation may be required to sustain behaviours over time. Social psychology might fruitfully move beyond askingwhetherhabit moderates the intention-behaviour relationship, and instead probehowandin which conditionshabits and intentions interact.

Habit formation is an important goal for behaviour change interventions because habitual behaviours are elicited automatically and are therefore likely to be maintained. This study documented experiences of habit development in 10 participants enrolled on a weight loss intervention explicitly based on habit-formation principles. Thematic analysis revealed three themes: Strategies used to support initial engagement in a novel behaviour; development of behavioural automaticity; and selecting effective cues to support repeated behaviour. Results showed that behaviour change was initially experienced as cognitively effortful but as automaticity increased, enactment became easier. Habits were typically formed in work-based contexts. Weekends and vacations temporarily disrupted performance due to absence of associated cues, but habits were reinstated on return to work. Implications for theory and practice are discussed.

Habitual behaviours are learned responses that are triggered automatically by associated environmental cues. The unvarying nature of most workplace settings makes workplace physical activity a prime candidate for a habitual behaviour, yet the role of habit strength in occupational physical activity has not been investigated. Aims of the present study were to: (i) document occupational physical activity habit strength; and (ii) investigate associations between occupational activity habit strength and occupational physical activity levels. A sample of UK office-based workers (n = 116; 53% female, median age 40 years, SD 10.52) was fitted with activPAL accelerometers worn for 24 h on five consecutive days, providing an objective measure of occupational step counts, stepping time, sitting time, standing time and sit-to-stand transitions. A self-report index measured the automaticity of two occupational physical activities (being active (e.g., walking to printers and coffee machines) and stair climbing). Adjusted linear regression models investigated the association between occupational activity habit strength and objectively-measured occupational step counts, stepping time, sitting time, standing time and sit-to-stand transitions. Eighty-one per cent of the sample reported habits for being active, and 62% reported habits for stair climbing. In adjusted models, reported habit strength for being active were positively associated with average occupational sit-to-stand transitions per hour (B = 0.340, 95% CI: 0.053 to 0.627, p = 0.021). Stair climbing habit strength was unexpectedly negatively associated with average hourly stepping time (B = -0.01, 95% CI: -0.01 to -0.00, p = 0.006) and average hourly occupational step count (B = -38.34, 95% CI: -72.81 to -3.88, p = 0.030), which may reflect that people with stronger stair-climbing habits compensate by walking fewer steps overall. Results suggest that stair-climbing and office-based occupational activity can be habitual. Interventions might fruitfully promote habitual workplace activity, although, in light of potential compensation effects, such interventions should perhaps focus on promoting moderate-intensity activity.

Background: The twelve-item Self-Report Habit Index (SRHI) is the most popular measure of energy-balance related habits. This measure characterises habit by automatic activation, behavioural frequency, and relevance to self-identity. Previous empirical research suggests that the SRHI may be abbreviated with no losses in reliability or predictive utility. Drawing on recent theorising suggesting that automaticity is the 'active ingredient' of habit-behaviour relationships, we tested whether an automaticity-specific SRHI subscale could capture habit-based behaviour patterns in self-report data. Methods: A content validity task was undertaken to identify a subset of automaticity indicators within the SRHI. The reliability, convergent validity and predictive validity of the automaticity item subset was subsequently tested in secondary analyses of all previous SRHI applications, identified via systematic review, and in primary analyses of four raw datasets relating to energy-balance relevant behaviours (inactive travel, active travel, snacking, and alcohol consumption). Results: A four-item automaticity subscale (the 'Self-Report Behavioural Automaticity Index'; 'SRBAI') was found to be reliable and sensitive to two hypothesised effects of habit on behaviour: a habit-behaviour correlation, and a moderating effect of habit on the intention-behaviour relationship. Conclusion: The SRBAI offers a parsimonious measure that adequately captures habitual behaviour patterns. The SRBAI may be of particular utility in predicting future behaviour and in studies tracking habit formation or disruption.

OBJECTIVES Interventions promoting habitual fruit consumption have the potential to bring about long-term behaviour change. Assessing the effectiveness of such interventions requires adequate habit and behaviour measures. Habits are based on learned context-behaviour associations, so measures that incorporate context should be more sensitive to expected habit and behaviour changes than context-free measures. This study compared context-specific and context-free measures of fruit consumption habit and behaviour following a 3-week habit formation intervention. DESIGN Prospective online study (n = 58). METHODS Behaviour frequency was assessed across five timepoints, retrospectively (Time 1 [T1], T5) or via daily diary data (uploaded weekly at T2, T3 and T4). Habit strength was assessed before (T1) and immediately after the intervention (T4), and again 2 weeks later (T5). Analyses of variance were run, with time and context specificity as within-subject factors, and habit and behaviour frequency as dependent measures. RESULTS An interaction between time and context specificity was found in both analyses (habit: F(2,114) = 12.848, p < .001, part.η2 = .184; behaviour: F(2,114) = 6.714, p = .002, part.η2 = .105). Expected habit formation patterns 5 weeks post-baseline were only detected by the context-specific habit measure. Likewise, increased behaviour frequency was only found when the target context was specified (p's < .001). CONCLUSIONS Assessments of purposeful dietary habit and behaviour change attempts should incorporate context-specific measurement.

Hagger (2019) offers an insightful synthesis of recent theoretical and empirical developments in understanding of habit and its relevance to physical activity. This commentary extends coverage of one such advance, namely the distinction between two manifestations of habit in physical activity: habitually ‘deciding’ to engage in activity (i.e. habitual instigation), and habitually ‘doing’ the activity (habitual execution). We explore the rationale for this distinction and argue that most contemporary theory and evidence around habitual physical activity – and by extension, Hagger’s review – implicitly focuses on instigation and neglects execution. We offer hypotheses around the potential roles that habitual execution may play in physical activity. Broadening the scope of inquiry within the field to more fully encompass habitual performance would achieve a more comprehensive and informative account that incorporates concepts of skill acquisition and mastery.

Translating research evidence into clinical practice to improve care involves healthcare professionals adopting new behaviours and changing or stopping their existing behaviours. However, changing healthcare professional behaviour can be difficult, particularly when it involves changing repetitive, ingrained ways of providing care. There is an increasing focus on understanding healthcare professional behaviour in terms of non-reflective processes, such as habits and routines, in addition to the more often studied deliberative processes. Theories of habit and routine provide two complementary lenses for understanding healthcare professional behaviour, although to date, each perspective has only been applied in isolation. To combine theories of habit and routine to generate a broader understanding of healthcare professional behaviour and how it might be changed. Sixteen experts met for a two-day multidisciplinary workshop on how to advance implementation science by developing greater understanding of non-reflective processes. From a psychological perspective ‘habit’ is understood as a process that maintains ingrained behaviour through a learned link between contextual cues and behaviours that have become associated with those cues. Theories of habit are useful for understanding the individual's role in developing and maintaining specific ways of working. Theories of routine add to this perspective by describing how clinical practices are formed, adapted, reinforced and discontinued in and through interactions with colleagues, systems and organisational procedures. We suggest a selection of theory-based strategies to advance understanding of healthcare professionals' habits and routines and how to change them. Combining theories of habit and routines has the potential to advance implementation science by providing a fuller understanding of the range of factors, operating at multiple levels of analysis, which can impact on the behaviours of healthcare professionals, and so quality of care provision. •Improving the quality of care involves changing healthcare professional behaviour.•Professional behaviour is driven by both reflective and non-reflective processes.•Changing non-reflective, habitual, or routine clinical behaviours is difficult.•Theory-based strategies can help address non-reflective clinical behaviours.•Future directions for research on non-reflective clinical behaviour are provided.