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Autonomous cars are becoming a more and more popular topic of research, although not without concerns from the public over the safety of this new technology (Kyriakidis, Happee, & Winter, 2014). To address such worries, there is careful examination of road accidents involving autonomous vehicles from technology providers (Google, 2015b). This shows the importance of safety while automation is becoming more robust. Car autonomy is a staged rather than binary process, with levels of autonomy increasing as driver involvement decreases (National Highway Traffic Safety Administration, 2013; SAE J3016 & J3016, 2014). Therefore, user interfaces are required that improve safety when driver involvement is reduced but still necessary. The handover, the point of transition of control from the car to the driver, and vice versa, is a critical part of this interaction. An effective warning mechanism for such a critical case is essential, as lack of clarity over who has control of the vehicle at a given moment can be catastrophic, e.g. (Politis, Brewster, & Pollick, 2015a).
In parallel, as vehicle automation increases, drivers are more likely to engage in tasks other than driving. Gaming is a popular activity that drivers are expected to engage in while the car is in autonomous mode, and is a topic of ongoing research, e.g. (Krome, Goddard, Greuter, Walz, & Gerlicher, 2015; Neubauer, Matthews, & Saxby, 2014). Due to the high level of concentration required by a game, a particularly demanding scenario would be attending to a critical handover while gaming. A critical handover often examined is an automation failure, since it happens unexpectedly, leaving little time to react (Gold, Damböck, Lorenz, & Bengler, 2013; Mok et al., 2015; Pfromm, Khan, Oppelt, Abendroth, & Bruder, 2015). Signifying handovers with multimodal warnings (Naujoks, Mai, & Neukum, 2014; Politis et al., 2015a), using varying message contents (Koo et al., 2014) and evaluating transition times (Gold et al., 2013; Christian Gold & Bengler, 2014) are important aspects of this critical case. However, there is no work on how critical handovers can be facilitated by multimodal warnings originating from the game area. In this study, we use an engaging tablet gaming task and test the time required to resume driving during an automation failure. Handover notifications are moved to the tablet and abstract versus language-based multimodal warnings are compared as alerts for this scenario, both being novel interventions.