With the development of highly automated driving functions, drivers will no longer be in full charge of the driving task and can instead engage in a variety of non-driving related tasks (NDRTs), such as reading or watching a movie. However, engaging in these tasks increases the risk of experiencing motion sickness in a car. So far, most studies have compared everyday tasks such as reading and watching movies regarding their impact on car sickness. In this on-road driving study, a more theoretical approach was taken and controlled tasks were chosen to compare certain task characteristics regarding their impact on car sickness. In a within subject design, N = 20 moderately to severely susceptible participants completed three experimental drives on separate days, each with one task. To induce car sickness, a standardized driving profile including highly dynamic manoeuvres was driven on open roads. Three tasks with different types of visual input were selected: an auditory n-back task, a static visual n-back task, and a dynamic visual task. Participants were instructed to look down at a tablet throughout the drive and not to look up through the windscreen in all conditions. Driving dynamics, task performance and mental workload of the tasks were used as control variables. The effect of the tasks on the occurrence of car sickness was evaluated using subjective misery scale ratings. On average a medium to high level of car sickness could be induced over all trials. The extent of car sickness differed significantly between task conditions. Both visual tasks produced more car sickness than the auditory task, with the visual dynamic task leading to the most severe symptoms. Visual input in NDRTs, particularly moving images, seem to play a crucial role for the occurrence of car sickness. Possible underlying mechanisms are discussed and methodological implications for the use of NDRTs in realistic driving studies to elicit car sickness are derived.
