use of SCMs, these findings point to the need for the use of more sophisticated designs
to distinguish measurement and predictive effects, e.g. including conditions without
baseline (time 1) questionnaires for comparative purposes. Moreover, the question-
behaviour effect suggests that SCMs are indeed tapping psychological processes crucial
to behaviour change.
THE INTENTION–BEHAVIOUR GAP
The intention–behaviour gap refers to the fact that intentions are far from perfect
predictors of behaviour. In this section we review two areas of research exploring this
gap. The first focuses on the stability of intentions across time while the second
examines the volitional processes that might be important in determining whether
intentions get translated into action.
Intention stability
In the vast majority of applications of SCMs the predictors of behaviour are measured
by questionnaire (at time 1) and then behaviour is measured at a second time point,
thereby employing a prospective survey method. One important requirement of such
a design is that the measured constructs (e.g. attitudes) will remain unchanged between
the measurement and the opportunity to act. So, for example, in using the TPB the
assumption is that intentions to exercise will remain the same from when the (time 1)
questionnaire is completed to the time points at which the respondent has the
opportunity to engage in exercise. This is one of the limiting conditions of the TPB.
However, cognitions including intentions may indeed change in this time period and
such change provides one important explanation of the intention–behaviour gap.
Several studies have now demonstrated that the intention–behaviour gap is indeed
reduced for individuals with intentions that are more stable over time. For example,
Conner, Norman and Bell (2002) found that intentions were stronger predictors of
healthy eating over a period of 6 years when these intentions were stable over a 6-
month time period. These findings show that intention stability moderates the
relationship between intention and behaviour.
A number of other factors have been found to influence the size of the intention–
behaviour gap. For example, anticipating feeling regret if one does not perform a
behaviour or perceiving a strong moral norm (that is, believing that one is morally
obliged to act) have both been found to significantly reduce the intention–behaviour
gap (see Cooke and Sheeran, 2004, for a review). Like Conner et al. (2002), Sheeran
and Abraham (2003) found that intention stability moderated the intention–behaviour
relationship for exercising but, more importantly, found that intention stability
mediated the effect of other moderators of the intention–behaviour relationship,
including anticipated regret. This suggests that the mechanism by which a number of
these other moderators may have their effect on intention–behaviour relationships
is through changing the temporal stability of intentions. Hence, factors that might be
expected to make individual intentions more stable over time would be expected
to increase the impact that these intentions have on behaviour and so reduce the
intention–behaviour gap.
HEALTH COGNITIONS AND BEHAVIOURS 159