Testing the capacity within an extended theory of planned behaviour to reduce the commission of driving violations

The capacity within an extended theory of planned behaviour (TPB) to change young drivers’ intentions and reduce their commission of driving violations was tested using regression-based statistical simulations. Participants (N = 198) completed questionnaire measures of TPB variables, plus moral norm and anticipated regret, each with respect to 11 different driving violations. One month later, subsequent behavioural performance was measured, again using self-completion questionnaires. Statistical simulations indicated substantial capacity within the extended TPB to reduce driving violations, with maximum changes to all of the cognitive predictors generating large degrees of intention and behaviour change (i.e. d > 0.80). However, the degree of intention change that was generated was greater than the degree of behaviour change, and sensitivity analyses demonstrated that behavioural interventions need to successfully change multiple cognitive variables in order to achieve meaningful reductions in driving violations. Implications of the findings for developing behaviour change interventions are discussed.