Health Psychology : a Textbook

Components of the TPB

The TPB emphasizes behavioural intentions as the outcome of a combination of several

beliefs. The theory proposes that intentions should be conceptualized as ‘plans of action

in pursuit of behavioural goals’ (Ajzen and Madden 1986) and are a result of the

following beliefs:


 Attitude towards a behaviour, which is composed of both a positive or negative

evaluation of a particular behaviour and beliefs about the outcome of the behaviour

(e.g. ‘exercising is fun and will improve my health’);


 Subjective norm, which is composed of the perception of social norms and pressures

to perform a behaviour and an evaluation of whether the individual is motivated to

Fig. 2-5 Basics of the theory of reasoned action

Fig. 2-6 Basics of the theory of planned behaviour

32 HEALTH PSYCHOLOGY