The effect of cognitive load on Detection-Response Task (DRT) performance during day- and night-time driving: a driving simulator study with young and older drivers

Over the past 25 years, distracted driving and driver inattention have been one of the main risk factors for road traffic safety. Previous research has shown that increased cognitive load from non-visual activities take our mind off the driving task, by engaging our working memory resources. Studies have shown that engagement in these tasks results in a more concentrated gaze towards the road centre, reducing lateral deviation (e.g., reduced standard deviation of lane position (SDLP) and less high frequency steering reversals). The Detection-Response Task (DRT) is an International Organization for Standardization (ISO) standard used to study the impact of cognitive load, due to secondary task, on performance. This driving simulator study examined the effect of varying levels of cognitive load (using the n-back task) on driving and DRT performance. The effect of age and lighting conditions was examined by comparing the performance of a younger group of drivers (Age Mdn = 22) with that of an older cohort (Age Mdn = 66) during day- and night-time driving conditions. Results showed that young drivers’ DRT performance was better at night-time compared to day-time, when compared to that of older drivers. Young drivers also performed better at the n-back task. Overall, an increase in cognitive load increased response time to the DRT task. In line with previous studies, an increase in cognitive load also reduced SDLP, but only in the absence of the DRT. These results provide new knowledge on drivers’ detection of peripheral stimuli during different lighting conditions, and how these are affected by a cognitively loading, non-visual, working memory task. The implications of these findings on real-world road safety are discussed.