The impact of courteous and discourteous drivers on physiological stress

Prior studies into road safety have concentrated largely on studying unsafe forms of driving behaviour such as aggressive, stressed, and risky driving. Little attention has been given to ‘positive’ driving behaviour, such as how pro-social driving may help to promote cooperation with other road users and decrease incidences of aggressive and stressful driving. This study aimed to compare the impact of courteous and discourteous driving on the immediate physical health of other drivers (blood pressure, heart rate, and markers of stress) whilst controlling for other recognized factors responsible for driver stress such as road infrastructure (e.g. roadworks, traffic lights, freeways) and driving maneuvers (e.g. merging, tail-gaiting, navigating roundabouts). Using actors in a deception study, a naturalistic driving scenario was created in a lab-based simulation. All participants (n = 10; 39 ± 14.5 years) drove the same route in a simulator and engaged with the same driving behaviours and other virtual road users on two separate occasions separated by 7 days. The difference between conditions was whether the participant interacted with other drivers who displayed: a) courteous or b) discourteous behaviours. Blood pressure, heart rate variability and salivary hormone concentrations (cortisol and alpha amylase) were measured before and immediately after each simulated drive. After interacting with the discourteous drivers, participants experienced significantly higher mean arterial blood pressure, systolic and diastolic pressure, central systolic and diastolic pressure, and heart rate, and lower heart rate variability (indicative of acute stress) compared to interacting with the courteous drivers. Conversely, these markers of stress were reduced after interacting with the courteous drivers. The results support courtesy on the road to provide short-term benefits for the recipient of the action, while also increasing road safety more generally.