Aggressive driving behaviours may be associated with greater crash risk in situations where drivers engage in riskier types of behaviours such as following too closely. It also appears that many drivers who do not normally regard themselves as angry or aggressive report engaging in aggressive driving acts. Qualitative studies have suggested that drivers explain these behaviours with reference to justified retaliation or beliefs that such acts ‘teach’ other drivers a ‘lesson’ or to exercise better driving manners or etiquette. Drivers may also argue that their behaviour does not have a negative impact on others. Such descriptions of motives bear a strong resemblance to the psychological mechanisms of moral disengagement. Moral disengagement is where individuals detach themselves from their usual self-regulatory processes or morality in order to behave in ways that run counter to their normal moral standards. Moral disengagement offers a potential explanation of how apparently ‘good’ or moral people commit ‘bad’ or immoral behaviours. Categories of moral disengagement are: cognitively misinterpreting the behaviour (e.g euphemistic labelling); disconnecting with the target (e.g. attributing blame to the target); and distorting or denying the impact of the behaviour. An on-line survey with a convenience sample of general drivers (N = 294) was used to explore the potential utility of moral disengagement in explaining self-reported driving aggression over and above the explanatory power provided by constructs that are normally associated with self-reported on-road aggression. Hierarchical regression analysis was used with measures of trait anger, driving anger (DAS), moral disengagement, and driving moral disengagement (an adaptation of the measure of moral disengagement for the driving context). Results revealed that the independent variables together explained 37% of the variation in self-reported driving aggression (as measured by the Driving Anger Expression scale, DAX). Driving moral disengagement was a significant predictor of driving aggression (p < .001) after accounting for the contribution of age, gender, driving anger, and moral disengagement. Moreover, inspection of the beta weights suggested that driving moral disengagement (beta = .57) was the strongest predictor for this sample, accounting for 20% of the unique variance in driving aggression (sr2 = .20). The pattern of results suggests drivers with higher tendencies to morally disengage in the driving context may respond to others more aggressively on-road. Moreover, driving moral disengagement appeared to add to our understanding of why some angry drivers do not respond aggressively on-road while others do. Seeking to prevent drivers from activating moral disengagement while driving may be worthy of exploration as a way of reducing non-violent, yet potentially still risky, forms of driving aggression
