Attentional Dynamics After Take-Over Requests: The Need for Handover Assistance Systems in Highly Automated Vehicles

Drivers in highly automated vehicles will frequently transition back to manual driving. Drivers performing Non-Driving Related Tasks (NDRTs) during automated driving are generally capable of deactivating automated systems approx. 3-6 s on average after a take-over request (e.g. Vogelpohl et al. 2018a). However, take-over time should not necessarily be considered a measure of take-over quality (e.g. Gold et al. 2016). In complex situations drivers may be prone to neglect lower priority sub-tasks (e.g. Richard et al. 2006). After take-over requests drivers may therefore be uncertain about the status of safety-relevant areas in the driving scene after they have deactivated the automation. This uncertainty can be characterized as a reduction in situation awareness (c.f. Johnson et al. 2017). We present research which shows that drivers may be slow to rebuild situation awareness after take-over requests based on delayed visual attention to lower priority sub-tasks such as looking at the mirror and looking at the speedometer. We discuss why we believe drivers' attentional dynamics (how and when attention is shifted; c.f. Lee 2014) after take-over requests should be taken into account for the design of automated driving systems. Future automated driving systems should consider not only how long a driver takes to deactivate the automation, but also take into account the process of how the driver transitions back to manual driving. If a driver neglects stages of the transition, a guided transition could ensure that uncertainty during the transition to manual driving is reduced and that situation awareness after the transition is regained as quickly and as efficiently as possible.