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Abstract
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It doesn't matter how beautiful your theory is, it doesn't matter how smart you are. If it doesn't agree with experiment, it's wrong. (Richard P. Feynman)
The Theory of Planned Behaviour (TPB; Ajzen, Citation1985), an extension of the Theory of Reasoned Action (TRA; Fishbein & Ajzen, Citation1975), has been the dominant theoretical approach to guide research on health-related behaviour for the past three decades. The theory is well recognised amongst researchers and is also familiar to many students, practitioners and policy-makers.
The TPB proposes that volitional human behaviour is a function of the intention to perform the behaviour and perceived behavioural control (PBC). Intention is hypothesised to be a function of attitudes towards the behaviour, subjective norm and perceived behavioural control. The degree to which PBC influences behaviour directly (rather than indirectly through intention) is hypothesised to depend on the degree of actual control over the behaviour. Attitudes, subjective norms and PBC are assumed to be based on the strength and evaluation of accessible behavioural, normative and control beliefs.
Moreover, the TPB makes three mediation hypotheses. Firstly, the effect of attitude and subjective norm on behaviour is hypothesised to be fully, and that of PBC on behaviour to be partially, mediated by intention. Secondly, the effects of behavioural, normative and control beliefs on intention and behaviour are hypothesised to be mediated through attitude, subjective norm and PBC, respectively. Lastly, the effect of all other biological, social, environmental, economic, medical and cultural influences is hypothesised to be mediated by the TPB (sufficiency assumption; Ajzen, Citation1985; Sutton, Citation2002).
The TPB has inspired a considerable amount of empirical health behaviour research. The vast majority of studies have used correlational designs to investigate cross-sectional and prospective associations between TPB cognitions and behaviour (Noar & Zimmerman, Citation2005). A recent systematic review of 237 independent prospective tests found that the TPB accounted for 19.3% of variability in health behaviour with intention being the strongest predictor (McEachan, Conner, Taylor, & Lawton, Citation2011). It was also found that the TPB was considerably less predictive of behaviour when studies used a longitudinal rather than a 'shortitudinal' design, when participants were not university students and when outcome measures were taken objectively rather than as a self-report... |
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Keywords
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Extending not retiring the theory of planned behaviour: a commentary on Sniehotta, Presseau and Araújo-Soares; From studying the determinants of action to analysing its regulation: a commentary on Sniehotta, Presseau and Araújo-Soares; Mapping modifiable mechanisms in health promotion research: a commentary on Sniehotta, Presseau, and Araújo-Soares; On retiring the TRA/TPB without retiring the lessons learned: a commentary on Sniehotta, Presseau and Araújo-Soares; Some retirees remain active: a commentary on Sniehotta, Presseau and Araújo-Soares; The theory of planned behaviour is alive and well, and not ready to retire: a commentary on Sniehotta, Presseau, and Araújo-Soares; Time to retire the theory of planned behaviour?: one of us will have to go! A commentary on Sniehotta, Presseau and Araújo-Soares; Will the new theories (and theoreticians!) please stand up? A commentary on Sniehotta, Presseau and Araújo-Soares |