The theory of planned behaviour

TPB was proposed by Ajzen and it is a cognitive theory about the factors that lead to an individuals decision to engage in a particular behaviour - according to TPB an individuals decision to engage in the behaviour can be directly predicted by their intention to engage in that behaviour

Behavioural attitude - ones own beliefs and attitudes about the behaviour and consequences of that behaviour

Subjective norms - views of society - persons belief about what others will think about their behaviour

Percieved behavioural control - the level of control an individual has over their ability to perform a behaviour - if it is high then they are more likely to avoid relapse

This model can be used not only to explain the processes that lead to an addiction but also as a way to understand prevention and treatment

It can be used to develop appropriate programmes to bring about long-lasting changes in addictive behaviour

the US office of national drug control launched a 2005 campaign to lower teenage marijuana use - success of this campaign is linked to the influence of attitudes - previous campaigns had focused on the risk of abuse such as an overdose but this wasnt found to be successful as teenagers are inclined to take risks - campaign tried to create a different attitude towards the effect of marijuana use - namely it affects making ones own decisions (being autonomous) and achieving aspirations (good grades) - target on attitudes may be the success of the current campaign - Slater

But - hard to measure the sucess of targetting behavioural attitude as they are correlations so we cannot assume the cause and effect - other factors may contribute to the decisions and the subsequent outcome

Campaigns also tend to view all teenagers as the same so doesnt take into account individual differences which may have an effect on their attitudes towards engaging in addictive behaviours

Anti-drug campaigns often aim to give adolescents actual data about the percentage of people engaging in risky behaviour - this is done to change the subjective norm

adolescents who smoke are usually part of a peer group who smoke and so they might think that smoking is the norm - but in fact most adolescents dont smoke so giving them exposure to statistics should correct the subjective norm of that individual and should form part of any campaign

So giving the truth about peer society should help the individual to see that addictive behaviours are not the norm and so they are less likely then to engage in that behaviour

Godin examined how well theory of planned behaviour could explain smoking intentions and behaviours - data was collected using questionnaires and trained interviews 

participants were surveyed at the start of the study and 6 months later 

researchers found 3 elements that helped to explain intentions whereas percieved behavioural control was the most important predictor of ultimate human behaviour as predicted by the model 

researchers concluded that prevention programmes should help smokers to focus on will power required to give up smoking and to alert smokers to the effort that is required to change smoking behaviour

A meta analysis by Armitage and Conner found that percieved behavioural control added an extra 6% of the variation intention compared to the assessment of attitude and subjective norm alone - so represents an improvement on the theory or reasoned action

But is the TPB too rational? when filling out questionnaires about attitudes and intentions people may not anticipate the emotions that compel their behaviour in real life - the presence of strong emotions may explain why some people sometimes act irrationally and fail to carry out any intention even when its in their best interest to do so

Reductionist? it ignores many other factors apart from emotion, but there are many other factors such as past experiences which may influence our behaviour

Substance abusers found that quitting was more successful in people who had decided themselves to give up rather than people who were forced to by health workers or court so the TPB needs to look at where the motivation comes from to quit and to change behaviour as this could be affecting the behaviour outcome and their intentions to change their behaviour

TPB predicts intentions rather than behavioural change - this could be a weakness as our intentions do not always lead to our behaviours

A strength for TPB is that is allows for individual differences - the model can be adapted to cater for anyone with any addiction - but however strong their self-efficacy is relates to their outcomes of behaviour - so this may influence behaviour outcome

White - looked at the sun protection intentions and behaviours in young people in a high risk skin cancer area in Australia

1000 pp's aged 12-20 completed a questionnaire assessing the behavioural attitude, subjective norm and perceived behavioural control - 2 weeks later pp's reported their sun protection behaviour for the previous fortnight - results showed that behavioural attitude, subjective norm and perceived behavioural control were significant in predicting the intention to engage in sun protection, and these intentions were significant predictors of actual sun protection behaviour

conclusions - this stidy shows that TPB does predict behaviours which suggests if we focus on the three predictors of behaviours then addicted can be prevented and or treated