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Interaction effects in the theory of planned behaviour: Predicting fruit and vegetable consumption in three prospective cohorts
Author(s) -
Kothe Emily J.,
Mullan Barbara A.
Publication year - 2015
Publication title -
british journal of health psychology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.05
H-Index - 88
eISSN - 2044-8287
pISSN - 1359-107X
DOI - 10.1111/bjhp.12115
Subject(s) - theory of planned behavior , psychology , structural equation modeling , consumption (sociology) , variance (accounting) , explained variation , repeated measures design , social psychology , control (management) , statistics , mathematics , social science , business , management , accounting , sociology , economics
Objective The theory of planned behaviour ( TPB ) has been criticized for not including interactions between major constructs thought to underlie behaviour. This study investigated the application of the TPB to the prediction of fruit and vegetable consumption across three prospective cohorts. The primary aim of the study was to investigate whether interactions between major constructs in the theory would increase the ability of the model to predict intention to consume fruit and vegetables (i.e., attitude × perceived behavioural control [ PBC ], subjective norm × PBC, subjective norm × attitude) and self‐reported fruit and vegetable intake (i.e., PBC × intention). Design Secondary data analysis from three cohorts: One predictive study (cohort 1) and two intervention studies (cohorts 2 and 3). Method Participants completed a TPB measure at baseline and a measure of fruit and vegetable intake at 1 week (cohort 1; n = 90) or 1 month (cohorts 2 and 3; n = 296). Results Attitude moderated the impact of PBC on intention. PBC moderated the impact of intention on behaviour at 1 week but not 1 month. Conclusion The variance accounted for by the interactions was small. However, the presence of interactions between constructs within the TPB demonstrates a need to consider interactions between variables within the TPB in both theoretical and applied research using the model.Statement of contribution What is already known on this subject?Previous studies have shown significant interactions between theory of planned behaviour ( TPB ) constructs. Interactions with the TPB have not been studied in food choice behaviour.What does this study add?The study revealed significant interactions between TPB variables. Attitude moderates the relationship between perceived behavioural control ( PBC ) and intention. Intention moderates the relationship between PBC and behaviour at 1 week but not 1 month.