title: Towards parsimony in habit measurement: testing the convergent and predictive validity of an automaticity subscale of the Self-Report Habit Index.
abstract: 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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Health Behaviour Research Centre, Department of Epidemiology & Public Health, University College London, Gower Street, London, UK. b.gardner@ucl.ac.uk
authors.forename: Benjamin
authors.initials: B
authors.lastname: Gardner
authors.forename: Charles
authors.initials: C
authors.lastname: Abraham
authors.forename: Phillippa
authors.initials: P
authors.lastname: Lally
authors.forename: Gert-Jan
authors.initials: GJ
authors.lastname: de Bruijn
mesh_terms: D000428:Alcohol Drinking; D002149:Energy Intake; D004734:Energy Metabolism; D015444:Exercise; D005247:Feeding Behavior; D006184:Habits; D015438:Health Behavior; D006801:Humans; D033182:Intention; D015203:Reproducibility of Results; D057566:Self Report