to form an implementation intention, the person must first identify a response that
will lead to goal attainment and, second, anticipate a suitable occasion to initiate
that response. For example, the person might specify the behaviour ‘go jogging
for 20 minutes’ and specify a suitable opportunity ‘tomorrow morning before
work’.Gollwitzer (1993) argues that, by making implementation intentions, individuals
pass control of intention enactment to the environment. The specified environmental
cue prompts the action so that the person does not have to remember or decide when
to act.
Sheeran et al. (2005) provide an in-depth review of both basic and applied research
with implementation intentions (see also Prestwich et al., 2015). For example, Milne,
Orbell and Sheeran (2002) found that an intervention using persuasive text based on
protection motivation theory prompted positive pro-exercise cognition change but did
not increase exercise. However, when this intervention was combined with
encouragement to form implementation intentions, behaviour change was observed
(see Gollwitzer and Sheeran, 2006, for a meta-analysis of such studies; Prestwich
et al., 2015 for a review of the use of implementation intentions to change health
behaviours). Thus implementation intention formation moderates the intention–
behaviour relationship demonstrating that two people with equally strong goal
intentions may differ in their volitional readiness depending on whether they have
taken the additional step of forming an implementation intention. Implementation
intention formation has been shown to increase the performance of a range of
behaviours with, on average, a medium effect size. Implementation intentions appear
to be particularly effective in overcoming a common problem in enacting intentions,
that is, forgetting. Provided effective cues are identified in the implementation
intention (i.e. ones that will be commonly encountered and are sufficiently distinctive),
forgetting appears to be much less likely. Implementation intentions also appear to help
individuals resist negative health behaviours (e.g. smoking initiation in adolescents;
Conner and Higgins, 2010) and recent research has suggested that pairs of individuals
can form joint implementation intentions that can be particularly effective (referred
to as collaborative implementation intentions; Prestwich et al., 2012).
SUMMARY
There is considerable variation in who performs health behaviours. Demographic
differences explain part of this variation, although such factors are not easily modifiable.
Various modifiable cognitions have been identified, which explain differences in who
performs health behaviours. Key cognitions include intentions, self-efficacy and
outcome expectancies (or attitudes). Cognitions have been incorporated in a number
of social cognition models (SCMs) that describe the key cognitions and how they are
interrelated in the determination of behaviour. The most important SCMs include the
health belief model, protection motivation theory, theory of reasoned action/theory
of planned behaviour and social cognitive theory. These models focus on the cognitive
antecedents of motivation. Stage models attempt to describe the process of behaviour
change from first consideration to maintenance of change but there is limited evidence
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