The interaction of cognitive load and working memory capacity while driving

What is it about?

Distracted driving has received increasing attention in the literature due to potential adverse safety outcomes. An often posed solution to alleviate distraction while driving is hands-free technology. Interference by distraction can occur however at the sensory input (e.g., visual) level, but also at the cognitive level where hands-free technology induces working memory (WM) load. Active maintenance of goal-directed behavior in the presence of distraction depends on WM capacity (i.e., Lavie’s Load theory) which implies that people with higher WM capacity are less susceptible to distractor interference. This study investigated the interaction between verbal WM load and WM capacity on driving performance to deter-mine whether individuals with higher WM capacity were less affected by verbal WM load, leading to a smaller deterioration of driving performance. Driving performance of 46 young novice drivers (17–25 years-old) was measured with the lane change task (LCT). Participants drove without and with verbal WM load of increasing complexity (auditory-verbal response N-back task). Both visuospatial and ver-bal WM capacity were investigated. Dependent measures were mean deviation in the lane change path (MDEV), lane change initiation (LCI) and percentage of correct lane changes (PCL). Driving experience was included as a covariate. Performance on each dependent measure deteriorated with increasing ver-bal WM load. Meanwhile, higher WM capacity related to better LCT performance. Finally, for LCI and PCL,participants with higher verbal WM capacity were influenced less by verbal WM load. These findings entail that completely eliminating distraction is necessary to minimize crash risks among young novice drivers.

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Why is it important?

Driver distraction has been defined as “the diversion of attention away from activities critical for safe driving toward a competing activity”. Distracted driving has received increasing attention in the literature due to adverse safety out-comes. At least 20–30% of the car crashes in the United States can be related to some form of driver distraction and distracted driving is a worldwide problem. Especially the use of cell-phones and in-vehicle technologies has created situations in which driving is combined with other tasks.