Theory of Planned Behaviour

Theory of Planned Behaviour

Purposeful behaviour has been a buzz phrase for me in the past few months and often working with clients we are inventing small seemingly unrelated purposeful behaviours to achieve. My reasoning for such small purposeful behaviours is not so much the behaviour change but the shift in perceived behavioural control. Behaviours are preceded by a range of variables and some the biggest predictors within that group are perceived behaviour control and attitude. This is demonstrated in the Theory of Planned Behaviour (TPB) which was proposed by Icek Ajzen (1991).



In a recent article by Arnautovska et al. (2018) which investigates Physical Activity (PA) in older adults, they provided a summary of TPB;

The TPB (Ajzen, 1991) proposes intention as the proximal predictor of behaviour. It is further hypothesised that intention is predicted by the three beliefbased constructs: attitude (advantages/disadvantages), subjective norm (perceived social approval/disapproval), and perceived behavioural control (facilitators/barriers). In addition, it is proposed that perceived behavioural control directly predicts behaviour. The strength of intention is predicted by a person's evaluation of the target behaviour, perceptions about approval of important others for performing the behaviour, and perceptions of control and ability in relation to behavioural performance. Findings from metaanalyses support the predictive ability of attitudes and perceived behavioural control on intention, with a weaker subjective norm–intention relationship often found (Downs & Hausenblas, 2005; Hagger, Chatzisarantis, & Biddle, 2002). In line with these findings, a review of TPBbased PA studies by Hagger et al. (2002), including persons of all ages, indicated that attitudes and perceived behavioural control were the best predictors of intention (ß = 0.40 and 0.33, respectively), and together with subjective norm predicted 45% of variance in intention. In addition, perceived behavioural control was found to be associated with PA, and together with intention explained 27% of the variance in behaviour.

Our behaviours are the end of the production line of cognitive assembly and therefore provide a function. Subjective norms, attitude and perceived behavioural control are key factors in the process and can be modified to result in modified intentions and therefore modified behaviours.


Ajzen, I. (1991). The theory of planned behavior. Organizational Behavior and Human Decision Processes50, 179–211.

Arnautovska, U., Fleig, L., O’Callaghan, F., & Hamilton, K. (2018). Older Adult’s Physical Activity: The Integration of Autonomous Motivation and Theory of Planned Behaviour Constructs. Journal of Australian Psychologist

Downs, D. S., & Hausenblas, H. A. (2005). The theories of reasoned action and planned behavior applied to exercise: A meta‐analytic update. Journal of Physical Activity and Health2(1), 76–97.

Hagger, M. S., Chatzisarantis, N. L. D., & Biddle, S. J. H. (2002). A meta‐analytic review of the theories of reasoned action and planned behavior in physical activity: Predictive validity and the contribution of additional variables. Journal of Sport and Exercise Psychology24(1), 3–32.