Display Alternatives for In-Vehicle Warning and Sign Information: Message Style, Location, and Modality

In-vehicle displays offer a promising alternative to road signs; however, little human factors research exists to guide their design. In this study, the authors examined message style, the physical grouping or location, and visual as opposed to auditory messages to identify how such message characteristics affect driving safety and compliance. Variables such as driver self-confidence, trust in the system, situation awareness, and workload helped explain the influence of in-vehicle messages on driving behavior. Data collected from 16 older and 16 younger drivers using a driving simulator suggest that message style may be an important design characteristic influencing both compliance and safety. Results indicate that command messages promote greater compliance but may also reduce safety. Results also suggest that message style merits further consideration along with more commonly studied design parameters of display modality and location. In-vehicle messages without redundant roadway signs led to lower levels of safety; this was probably due to drivers distributing their attention inappropriately as opposed to in-vehicle messages exceeding their information-processing limits.