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Kothe - EHPS - Theory of planned behaviour cognitions do not predict change in fruit and vegetable consumption
1. Theory of planned behaviour cognitions do not
predict change in fruit and vegetable
consumption
Emily Kothe & Barbara Mullan
School of Psychology, The University of Sydney, Australia
emily.kothe@sydney.edu.au & barbara.mullan@sydney.edu.au
Abstract Results Results (cont).
Background The present study investigated whether Theory of planned behaviour accounted for 17% of
theory of planned behaviour (TPB) cognitions variance in fruit and vegetable intake at baseline.
predicted change in fruit and vegetable intake in a trial
cohort of Australian young adults. Attitude Theory of planned behaviour accounted for 24% of
T1 variance in fruit and vegetable intake at follow-up.
Methods Participants of a randomised controlled trial
of a TPB-based intervention (N=162) completed Theory of planned behaviour accounted for just 2.3%
questionnaires assessing fruit and vegetable intake of variance in change in fruit and vegetable
and TPB constructs at baseline and 30 days. consumption.
Fruit and
Findings The theory of planned behaviour predicted Subjective .42 Intention .37 vegetable
fruit and vegetable consumption at baseline and norm Conclusion
T1 intake
follow-up. Change in attitude, perceived behavioural T1
control and subjective norm predicted change in T1
intention, but change intention and perceived Failure of the theory to predict change in fruit and
behavioural control failed to predict change in fruit and vegetable consumption may reflect artefacts of the
vegetable intake study design.
Perceived
Discussion Failure of the theory to predict behaviour behavioural However, the lack of support for the theory of planned
change may be due to the inadequacy of the theory or control behaviour when applied to the modelling of behaviour
to artefacts of the study design that facilitate change in T1 change is consistent with a other recent intervention
fruit and vegetable consumption without corresponding studies based on the theory.5
changes in cognitions. Researchers should be
cautious when interpreting empirical support for the Researchers should not assume that theories that
predictive utility of the TPB as evidence the theory can Figure 1. Theory of planned behaviour variables successfully predict behaviour (either crosssectionally
be applied to behaviour change. predicted fruit and vegetable consumption at T1 or prospectively) will adequately model change in
beta weights shown, significant paths in dark blue
behaviour.
Introduction More research on the mediation of behaviour change
through theory relevant pathways are needed to
Attitude confirm or clarify these findings.
T2
Australian young adults are less likely than any other
age group to consume adequate quantities of fruit and Acknowledgments
vegetables.1
The theory of planned behaviour has previously been
Fruit and
found to predict a large proportion of the variance in Subjective .40 Intention .18 vegetable
intake in this population. 2,3,4 norm
T2 intake
T2
T2
Objectives
To determine whether change in fruit and vegetable Perceived
consumption in the FreshFacts study could be behavioural
explained by change in theory of planned behaviour control
cognitions. T2
Methods
Figure 2. Theory of planned behaviour variables
predicted fruit and vegetable consumption at T2
beta weights shown, significant paths in dark blue This research would not have been possible without
University undergraduates (N=162) completed a
theory of planned behaviour intervention designed to the support of staff and students at the University of
increase fruit and vegetable intake. Sydney. The researchers would especially like to thank
Vanessa Allom, Kirby Sainsbury, Jemma Todd, Alyssa
Participants were randomised to either the intervention Milton and Kristina Xavier.
Attitude
or control conditions.
change
All participants completed a theory of planned References
behaviour questionnaire and a self-report measure of
fruit and vegetable consumption at baseline and
immediate post-intervention follow-up (Day 30). 1. Australian Bureau of Statistics. National Nutrition
Change in Survey. Canberra 1997
Subjective .14 .03 fruit and
Baseline norm Intention
vegetable
2. Allom V, Mullan B. Self-regulation versus habit: The
influence of self-schema on fruit and vegetable
change
assessment intake consumption. Psychology & Health. 2011.
3. Kothe EJ, Mullan B, Butow P. Promoting fruit and
(n=180) vegetable consumption: Testing an intervention
based on the theory of planned behaviour. Appetite.
Perceived 2012;58(3).
4. Collins A, Mullan B. An extension of the theory of
Control Intervention behavioural
control planned behavior to predict immediate hedonic
change behaviors and distal benefit behaviors. Food
(n=90) (n=90) Quality and Preference. 2011;22(7).
5. Hardeman W, Kinmonth AL, Michie S, Sutton S.
Theory of planned behaviour cognitions do not
Follow-up assessment Figure 3. Change in theory of planned behaviour
variables did not predict change in fruit and vegetable
predict self reported or objective physical activity
levels or change in the ProActive trial. British
consumption Journal of Health Psychology. 2011;16(1):135-50.
(n=162) beta weights shown, significant paths in dark blue