Twist It, Touch It, Push It, Swipe It: Evaluating Secondary Input Devices for Use with an Automotive Touchscreen HMI

Touchscreen Human-Machine Interfaces (HMIs) inherently demand some visual attention. By employing a secondary device, to work in unison with a touchscreen, some of this demand may be alleviated. In a medium-fidelity driving simulator, twenty-four drivers completed four typical in-vehicle tasks, utilising each of four devices -- touchscreen, rotary controller, steering wheel controls and touchpad (counterbalanced). Participants were then able to combine devices during a final 'free-choice' drive. Visual behaviour, driving/task performance and subjective ratings (workload, emotional response, preferences), indicated that in isolation the touchscreen was the most preferred/least demanding to use. In contrast, the touchpad was least preferred/most demanding, whereas the rotary controller and steering wheel controls were largely comparable across most measures. When provided with 'free-choice', the rotary controller and steering wheel controls presented as the most popular candidates, although this was task-dependent. Further work is required to explore these devices in greater depth and during extended periods of testing.