The existence and impact of the Psychological Refractory Period effect in the driving environment

Driver distraction from in-vehicle tasks can have negative impacts on longitudinal and lateral vehicle control and brake reaction time. The distraction problem is wellestablished in the literature, and is increasing due to advances in the functionality, availability, and number of in-vehicle systems. One approach to a solution is managing in-vehicle task presentation to reduce associated distraction. This paper reports a driving simulator experiment, designed to investigate the existence of the Psychological Refractory Period in the driving context and its effect on driver performance. The PRP effect is observed when a surrogate in-vehicle task is presented in close temporal proximity to a lead vehicle braking event. Brake responses are subject to an increasing delay as the interval to an in-vehicle task is decreased. In-vehicle task modality modulates this effect. The impact of the PRP effect on driving performance is quantified and recommendations are made for reducing the driver distraction problem through the management of in-vehicle task timing and modality. The potential impact of these results on driver safety is discussed.