Theory of planned behaviour and road violations: The moderating influence of perceived behavioural control

Understanding the motivation behind unsafe driving practices is of paramount importance with a view to preventing road violations and crashes. Although the vast majority of previous studies have reported the predictive utility of the theory of planned behaviour (TPB), these studies have been conducted within an additive framework. The present study aimed to better understand the role of the TPB constructs in predicting drivers’ road violation intentions and behaviours by investigating the interaction between differentiated Perceived Behavioural Control (PBC) components (i.e. perceived capacity and autonomy) and the other TPB factors on intention and road violations. We hypothesised that attitudes or subjective norms would affect intention, and that intention would affect behaviour, only to the degree that they are accompanied by high perceived capacity or high perceived autonomy. Participants (n = 280) completed two surveys 6 months apart: the first survey (Time 1) assessed the TPB components (i.e., attitude, subjective norm, perceived behavioural control and intention); the second survey (Time 2) reported road violation behaviours. The moderator effect of differentiated PBC components was inconsistent across road violation behaviours. Drink-driving was the road violation that was best predicted by the interactive TPB components, such as both perceived capacity and autonomy moderate the contribution of subjective norms on intention formation and perceived capacity moderate the prediction of behaviour by intention. Globally, TPB was a predictor of road violation intentions and behaviours, with both additive and interactive effects. From a practical standpoint, contemporary theories of attitudes and beliefs should consider the possibility of the interactive framework for a more precise prediction of road safety behaviour.

► Additive and interactive effects of TPB on road violations intention and behaviours.
► Moderating influence of PBC components on the prediction of road violations.
► The moderator effect of PBC components varies across drivers’ behaviours.
► The interactive effects of TPB components best predicted drink-driving.