Theory of Planned Behaviour

Question 1

Theory of Planned Behaviour (TPB).

Answer 1

Icek Ajzen (1985, 1991).
Theory of how we can change our behaviour deliberately through rational decisions - evaluate the positive and negative consequences.
TPB assets that therefore our behaviour can be predicted from our intentions.
TPB aims to link intentions with actual changes in behaviour.

Question 2

TPB suggests our intentions to use (give up) drugs arise from three key influences:

Answer 2

Our personal attitudes.
Subjective norms.
Perceived behavioural control.

Question 3

Personal attitudes.

Answer 3

A combination of favourable and unfavourable opinions about their addictions.
Formed by the person evaluating the positive and negative consequences of their addiction-related behaviour.
Attitudes may become unfavourable and lead to reduced interest in addiction-related behaviour.

Question 4

Subjective Norms.

Answer 4

Addicted person’s beliefs about whether those who matter most to them approve/disapprove of their addictive behaviour.
Beliefs based on what an addicted person believes to be ‘normal’ behaviour.
Addicted person considers what their friends and family would think if they knew about the addiction.

Question 5

Perceived Behavioural Control.

Answer 5

How much control we believe we have over our behaviour.
Depends on their perception of the resources available to them, both external (time, support) and internal (ability, effort).
According to TPB, perceived behavioural control has 2 possible effects.
First, it can influence our behaviour indirectly via our intentions to behave, so that the more control I believe I have over my ability to stop gambling, the stronger the intention to do so.
Second, this is the only one of the three TPB components that can influence behaviour directly, so the greater my perceived control over the addiction, the longer and harder they will try to stop.

Question 6

Limitation.

P: Some research has found short-term effects only.

Answer 6

E: Rosie McEachan et al (2011) conducted a meta-analysis of 237 tests of the TPB in predicting health behaviours. They found that the strength of the correlation between intentions and behaviour varied according to the length of time between the two. Intention to stop drinking cab predict actually giving up drinking, but only if the time between intention and behaviour is less than about 5 weeks.
E: The evidence is much weaker when the time interval between intentions and behaviour is longer.
L: Therefore intentions may not predict changes to addiction-related behaviour in the longer term, limiting the usefulness of the TPB.

Question 7

Limitation.

P: It cannot account for the intention-behaviour gap.

Answer 7

E: The theory cannot adequately explain how actual behaviours are caused by intentions. Rohan Miller and Gwyneth Howell (2005) studied the gambling behaviour of underage teenagers. They found strong support for some parts of the TPB.
E: The key element of TPB was not supported - the intentions were not related to the actual gambling behaviour. Many psychologists now questions whether the TPB is a theory of behaviour change at all.
L: Therefore if the theory cannot predict behaviour change, we cannot use it to help change behaviour.

Question 8

Strength and limitation.

P: There is research evidence evidence support it.

Answer 8

E: In a study by Martin Hagger et al (2011) 486 participants completed questionnaires about their alcohol-related behaviours (and completed them again 1 and 3 months later). The researchers found that personal attitudes, subjective norms and perceived behavioural control all correlated significantly with the intention to limit drinking to the guideline number of units.
E: Intentions were also found to predict the number of units actually consumed after one month and three months. Perceived behavioural control predicted actual unit consumption directly and not just intention. These findings support the theory.
P: However, the findings of the study were not all supportive of the TPB.
E: The study failed to predict some alcohol-related behaviours. For example, attitudes, norms, control and intentions did not correlate significantly with the no of binge-drinking sessions after 1 month or 3.
E: Based on these findings, it appears that the success of the TPB may depend on the type of addiction-relates behaviour being measured.
L: This suggests that even supportive research indicates that the predictive validity of TPB is limited.