Benjamin Gardner Sood Health Behaviour Research Centre, UCL b.gardnersood@ucl.ac.uk 23rd April 2012

1. How should we
measure habit?
(And does it matter?)
Benjamin Gardner Sood
Health Behaviour Research Centre, UCL
b.gardnersood@ucl.ac.uk
23rd April 2012

2. What is a ‘habit’?
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3. Conceptualisations of habit
• “Learned sequences of acts that have become
automatic responses to specific cues”
(Verplanken & Aarts, 1999; also Hull, 1943; James, 1890)
• Learned
– through context-dependent repetition (Lally et al, 2010)
• Cue-dependent
• Automatic 3

4. Habitual versus intentional behaviour
Habitual behaviour Intentional behaviour
Bottom-up Top-down
Directly cued Consciously mediated
Impulsive Deliberative
Does not require intention Requires intention
Effortless initiation Effortful initiation
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5. Habit-behaviour effects (in associated contexts)
Triandis (1977)
1. Habit strength will be associated with behaviour
frequency
2. Habit strength will moderate the intention-
behaviour relationship:
- where habit is strong, intentions have weakened
impact on behaviour
- where habits and intentions conflict, behaviour more
likely to be habitual than intentional
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6. Habit as moderator of int-bhvr relation
Triandis (1977)

7. Automaticity is the essence of habit
Gardner (in press); Sniehotta & Presseau (2012)
1. Habit strength will be associated with behaviour
frequency
… because stronger cue-response automaticity
is more likely to prompt behaviour
2. Habit strength will moderate the intention-
behaviour relationship
… because habits are more immediately
enacted than are intentions 7

8. How to measure habit?
• Self-reporting habit is problematic
– Different interpretations of word ‘habit’
– Can people reliably reflect on automatic actions? (Eagly
& Chaiken, 1993)
• Past behaviour?
– Correlates with future behaviour
– Often moderates intention-behaviour relation (e.g.
Norman & Conner, 2006)
– Captures only behavioural stability
– And stable determinants of behaviour
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– These determinants may or may not include habit

9. How to measure habit?
Objective measures?
• Response times
– Faster = more cognitively accessible = habitual
– Cannot distinguish between habit and rapid deliberation
• Implicit associations
– E.g. lexical decision tasks (‘gym’ > ‘running’)
– Word cues (‘gym’) may not capture real-world cues (the
physical gym location)
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10. How to measure habit?
The Self-Report Habit Index
Verplanken & Orbell (2003)
• 12 items
• Incorporates
– Automaticity
– Behavioural frequency
– Self-identity relevance
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11. Verplanken & Orbell (2003, p1329)

12. SRHI appears adequate
• Reliable (alpha >.90)
• Single-factor structure
• Convergent validity with existing measures
(Verplanken et al, 2005)
• Moderates intention-behaviour relationship
(e.g. Gardner, de Bruijn & Lally, 2011)
• Assumes people can be aware on reflection that
they were not aware when performing behaviour
(Gardner, Abraham, Lally & de Bruijn, under review)

13. Towards precision in habit
measurement:
Refining the SRHI
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14. Is identity a necessary component of habit?
“[H]abits are part of how we organize everyday life and
thus might reflect a sense of identity or personal style. We
thus assumed that although this might not hold for all
habits, at least some might be descriptive of a person and
thus express someone’s identity.”
Verplanken & Orbell (2003, p1317; emphasis added)
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15. Is identity necessary in the SRHI?
Gardner, de Bruijn & Lally (in press)
• SRHI tests are biased against extraction of
identity as separate factor:
– Cronbach’s alpha increases with item quantity
– Factor analysis criterion (eigenvalue > 1) not useful
where one true factor is loaded on by only one item
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16. Is identity necessary in the SRHI?
Gardner, de Bruijn & Lally (in press)
• What happens when SRHI is augmented with 4
additional self-identity items?
• SRHI: ‘Drinking more than 8 units on one
occasion is something that’s typically “me”’
• Identity: ‘It would be out of character for me not to
drink more than 8 units on one occasion’
Sparks & Shepherd (1992)
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17. Is identity necessary in the SRHI?
Gardner, de Bruijn & Lally (in press)
• N = 167 UK students
• Prospective design
– Habit, identity, TPB measured at baseline
– Number of binge-drink sessions reported one week later
• Best model in confirmatory factor analysis:
– SRHI (minus ‘typically me’ item) = Factor 1
– Identity (‘typically me’ SRHI item + 4 items) = Factor 2 17

18. Integrating habit and identity into TPB
Gardner, de Bruijn & Lally (in press)
• Identity:
– predicted intention, not behaviour
• Habit:
– predicted behaviour, not intention
– moderated intention-behaviour relationship
(but in ‘wrong’ direction!)
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19. What does frequency add to the SRHI?
• A crude proxy for context-dependent repetition
• Conceptual error (Gardner, in press)
– Once formed, habits need not be frequently performed
– Habit will be elicited only as frequently as cue is
encountered
• e.g. habits for eating popcorn in cinema are only elicited when
visiting the cinema
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20. What does frequency add to the SRHI?
• Methodological error
– Frequency is not directly responsible for habit-
behaviour effects (Gardner, in press)
• May capture habit and non-habit influences on
behaviour (Ajzen, 2002)
• Can habit-behaviour effects be captured by
automaticity alone?
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21. Content validation of SRHI
Gardner, Abraham, Lally & de Bruijn (under review)
Aim: To systematically extract parsimonious subset
of automaticity items
- Discriminant content validity (Pollard & Johnston, 2005)
- 7 participants asked to rate extent to which each
SRHI item met definitions of automaticity, identity
and frequency
- Yes (+1) vs No (-1)
- Confidence (0-10) 21

23. Content validation of SRHI
Gardner, Abraham et al (under review)
• Of 12 items:
– 3 not consensually thought to measure automaticity,
frequency, or identity
• ‘makes me feel weird if I do not do it’
• ‘something that belongs to my (daily, weekly, monthly) routine’
• ‘I have been doing a long time’
– 1 judged to measure frequency (‘I do frequently’)
– 1 judged to measure identity (‘typically “me”’)
– 7 judged to measure automaticity
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24. Content validation of SRHI
Gardner, Abraham et al (under review)
• All judges 90+% confident that four items
measured automaticity:
– “I do automatically”
– “I do without having to consciously remember”
– “I do without thinking”
– “I start doing before I realise I’m doing it”
= ‘Self-Report Behavioural Automaticity Index’
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(SRBAI)

25. Criteria for assessing the SRBAI
Gardner, Abraham et al (under review)
• Criteria?
– Reliability (alpha) & convergent validity
– Least worst option is to evaluate against well-developed
theoretical criteria
• Correlation with behaviour
• Moderation of intention-behaviour relationship
• Because of removal of behavioural frequency
items…
– Correlation: SRBAI-behaviour r < SRHI-behaviour r
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– Moderation: More clearly detected using SRBAI

26. Data sources
Gardner, Abraham et al (under review)
Secondary data
• Systematic database search
• (47) papers citing Verplanken & Orbell (2003)
• Corresponding authors asked to reanalyse using
SRBAI
– Reliability (45 tests)
– Habit-behaviour correlations (28 tests)
– Moderation tests (7 tests)
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27. Data sources
Gardner, Abraham et al (under review)
Primary data
• Four datasets
– Inactive (car) and active (bicycle) commuting
– Snacking (habit vs intention conflict)
– Alcohol consumption with evening meal (habit incl.
potential context cue)
• Comparison of SRBAI with SRHI and 8-item ‘non-
SRBAI’ scale
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28. Secondary data analyses
Gardner, Abraham et al (under review)
Reliability:
• 40 tests showed SRBAI alpha >=.80
Meta-analysis of correlations:
• SRHI-SRBAI, r = .92***
• SRBAI-behaviour, r = .42*** Z for
difference =
• SRHI-behaviour, r = .47*** 14.40***
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29. Secondary data analyses
Gardner, Abraham et al (under review)
Moderation:
• 4 tests: SRBAI and SRHI both found moderation
• 1 test: Neither SRBAI nor SRHI found moderation
• 1 test: SRHI found moderation, SRBAI did not
• 1 test: SRBAI detected tendency (p=.052; in
‘wrong’ direction), SRHI did not 29

30. Primary data analyses
Gardner, Abraham et al (under review)
Reliability:
• SRBAI alpha >.80
Correlations:
• SRHI, SRBAI and non-SRBAI correlated >=.90
• 3 datasets: rSRBAI-bhvr < rSRHI-bhvr
• 1 dataset: rSRBAI-bhvr = rSRHI-bhvr
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31. Primary data analyses
Gardner, Abraham et al (under review)
Moderation tests:
• Commuting: SRBAI, SRHI and non-SRBAI found
moderation
• Snacking: No habit index found moderation
• Alcohol consumption: SRBAI found moderation,
SRHI and non-SRBAI did not
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32. Conclusions of SRBAI tests
Gardner, Abraham et al (under review)
• SRBAI more conceptually precise & parsimonious
• As sensitive to hypothesised moderation
• Lower correlation with bhvr, due to removal of
potential noise
• Repetition history items only needed to demarcate
habit from other automatic actions
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33. Habit measurement matters!
• Measurement precision is crucial
• Developments in habit theory and application
depend on adequate measures of habit
• Inadequate measures may misdirect development
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34. Towards better habit measurement
Cue-relatedness
• Cues can be incorporated into SRHI/SRBAI
– ‘Drinking alcohol with the evening meal’
• But if ‘wrong’ cue is chosen, habit will not be
detected
vs
• Context-free habit measures
– ‘Drinking alcohol’
• (Probably) captures only reflection on overall
automaticity across contexts 34

35. Towards better habit measurement
Study design
• Group-level data are limited
– Cues and responses are idiosyncratic
– What does moderation of intention-behaviour
relationship at group level mean?
• Individual-level studies needed (e.g. N-of-1)
• Group-level studies should be seen as pilot data
– Effects need to be explored further at individual-level 35

36. Towards better habit measurement
Is self-report adequate?
• Still largely unclear whether people can accurately
reflect on habits
• SRBAI (and SRHI) require validation against
‘objective’ measures
• We should be open to new measures (e.g. in-situ
observations)
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37. Thank you!
b.gardnersood@ucl.ac.uk
Key references:
Gardner (in press [June 2012]) Habit as automaticity, not frequency. European
Health Psychologist.
Gardner, Abraham, Lally & de Bruijn (under review)
Gardner, de Bruijn & Lally (in press) Habit, identity and repetitive action: A
prospective study of binge-drinking in UK students. Brit J Health Psychol.
Gardner, de Bruijn & Lally (2011) A systematic review and meta-analysis of
applications of the Self-Report Habit Index to nutrition and physical activity
behaviors. Annals of Behav Med, 42, 174-187.
Sniehotta & Presseau (2012) The habitual use of the Self-Report Habit Index.
Annals of Behav Med, 43, 139-140.
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