Drivers’ Attention to Dash-based Human-Machine Interfaces: The Effect of Partial Automation and Cognitive Load

A vehicle’s dash-based Human-Machine Interface (HMI) provides critical information to drivers. However, the location of these displays can take drivers' visual attention away from the forward view and compromise safety. As vehicle automation becomes increasingly common, its impact on drivers’ visual attention to dash-based HMI remains under-explored. Moreover, drivers tend to engage more frequently in non-driving-related tasks during automation, but how the cognitive load imposed by these tasks affects drivers’ inspection of HMI displays is unclear. This driving simulator study examined how partial automation and cognitive load (imposed by a 2-back task) influence drivers’ visual attention to dash-based HMI containing speed and automation status information (N=41). Results showed that increased levels of automation and cognitive load additively reduced drivers’ visual attention to the dash area. Drivers prioritized inspecting the speedometer over the automation status information across all conditions. Our findings provide important implications for HMI design in automated vehicles.