AO3 - Theory of Planned Behaviour

• Research to support the theory of planned behaviour comes from Haggar et al. They asked 486 ppts to complete questionnaires about their alcohol-related behaviours at the start of the research and then one and three months later. They found that personal attitudes and subjective norms correlated significantly with the intention to limit drinking to match guidelines. Perceived control predicted actual unit consumption. increasing its validity in explaining behaviour change in addiction. This supports the TPB as the three components interact to affect an individual’s intention to stop.
• However, a problem with much of the research into TPB is that they rely on questionnaires which are prone to social desirability. Individual’s may lie about their intentions towards their addiction in order to present themselves in the best possible light. For example, they may say they intend to drink within guidelines to avoid being judged. Therefore, this reduces the validity of the research supporting TPB of behaviour change.
• A strength of TPB is that it has led to practical applications. This is because the principles of TPB can be used to predict who therapy is most likely to be successful for example, if person missing one of the components. This has valuable implications for the economy by helping the NHS prioritise their limited resources on individuals with high intention to change and reducing waiting times for therapy. Therefore, TPB is an important area of applied psychology as it can be used to inform addiction treatment in the real world.
• However, a limitation is that TPB assumes addiction is the result of rational decisions. In research ppts are asked about their intentions and attitudes towards the addictive behaviour. At this point they may be thinking more rationally however, in the moment when faced with their addiction and deciding about whether to do the addictive behaviour or not, emotions, stress (e.g. triggers for cravings) and cognitive biases may make them make irrational choices which TPB does not account for. TPB is based on rational thoughts which may ultimately not be reflected in actual behaviour.