Theory of Planned Behaviour


What is it?

The theory of planned behaviour (TPB) is a theoretical model used to predict intentions that are then used to predict actual behaviour. The theory posits that if one has an understanding of attitudes, subjective norms, and perceived behavioural control then one can create a highly predictive estimate of an agent’s intentions to behave in a certain way.

Attitudes—how one feels about a behaviour

Subjective norms—the perceptions we hold about how important others will feel about what we do

Perceived Behavioural Control—one’s perception of efficacy regarding behaviour.

Why is it important for behaviour change?

Understanding the underlying determinants to behaviour is an important prerequisite to changing behaviour.


How could you apply this theory?

  • While designing strategies maintain an awareness that attitudes, norms, and efficacy will all eventuate to behavioural change.

  • While investigating the context that surrounds a behaviour these three determinants should serve as a baseline to ascertain what drives an actor to perform a specific behaviour (i.e. do they feel capable of performing the action).

Example of theory applied

There was once a time my grandmother asked me to take her to the bank to transfer money between her cheque and savings accounts. I asked her why she didn’t want to just do it online. She responded that she didn’t know how to do it online; that she felt uneasy about all these new technological changes and that she didn’t trust the Internet; and finally, all of her friends—who were reminiscent of a simpler time—still went to the bank.


Ajzen, I. (1985). From Intentions to Actions: A Theory of Planned Behavior. In: Kuhl J., Beckmann J. (eds) Action Control. Springer, Berlin, Heidelberg. Retrieved from

Ajzen, I. (1991). The theory of planned behavior. Organizational Behavior and Human Decision Processes, 50(2), 179–211.

Armitage, C. J., & Conner, M. (2001). Efficacy of the Theory of Planned Behaviour: A meta-analytic review. British Journal of Social Psychology, 40(4), 471–499.

Hardeman, W., Johnston, M., Johnston, D., Bonetti, D., Wareham, N., & Kinmonth, A. L. (2002). Application of the Theory of Planned Behaviour in Behaviour Change Interventions: A Systematic Review. Psychology & Health, 17(2), 123–158.

Related Concepts

Lewin’s Force Field Analysis


Theory of Reasoned Action