How should wemeasure habit?

(And does it matter?)

Benjamin Gardner SoodHealth Behaviour Research Centre, UCL

b.gardnersood@ucl.ac.uk23rd April 2012

What is a ‘habit’?

2

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

• Automatic3

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

4

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 intentional5

Habit as moderator of int-bhvr relationTriandis (1977)

Automaticity is the essence of habitGardner (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

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

– These determinants may or may not include habit8

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)9

How to measure habit?The Self-Report Habit IndexVerplanken & Orbell (2003)

• 12 items

• Incorporates

– Automaticity

– Behavioural frequency

– Self-identity relevance

10

Verplanken & Orbell (2003, p1329)

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)

Towards precision in habit measurement:

Refining the SRHI

13

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)

14

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

15

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)

16

• 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 217

Is identity necessary in the SRHI?Gardner, de Bruijn & Lally (in press)

Integrating habit and identity into TPBGardner, de Bruijn & Lally (in press)

• Identity:

– predicted intention, not behaviour

• Habit:

– predicted behaviour, not intention

– moderated intention-behaviour relationship

(but in ‘wrong’ direction!)

18

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

19

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?

20

Content validation of SRHIGardner, 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

Content validation of SRHIGardner, 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 automaticity23

Content validation of SRHIGardner, 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’

(SRBAI)24

Criteria for assessing the SRBAIGardner, 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

– Moderation: More clearly detected using SRBAI 25

Data sourcesGardner, 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)26

Data sourcesGardner, 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’ scale27

Secondary data analysesGardner, Abraham et al (under review)

Reliability:

• 40 tests showed SRBAI alpha >=.80

Meta-analysis of correlations:

• SRHI-SRBAI, r = .92***

• SRBAI-behaviour, r = .42***

• SRHI-behaviour, r = .47***28

Z for difference =

14.40***

Secondary data analysesGardner, 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

Primary data analysesGardner, 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

30

Primary data analysesGardner, 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

31

Conclusions of SRBAI testsGardner, 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

32

Habit measurement matters!

• Measurement precision is crucial

• Developments in habit theory and application

depend on adequate measures of habit

• Inadequate measures may misdirect development

33

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 contexts34

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

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)36

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, 139-140.37