A validation study of a fixed-based, medium fidelity driving simulator for human-machine interfaces visual distraction testing

Studies comparing results captured in a simulator with those on road are important to validate the approach but are scarce in the context of secondary task distraction due to the potential ramifications of diverting attention away from safe driving. The authors compare distraction-related data from two studies exploring human-machine interfaces (HMI) design: one conducted in a static, medium-fidelity driving simulator with a vehicle enclosure and immersive visual environment, and one conducted on road. In both, 19 drivers undertook an identical selection of touchscreen, point-and-select tasks. The magnitude of visual distraction (defined as off-road glances directed towards the touchscreen) differed between the road and the simulator, with drivers making more and longer off-road glances when interacting with the interface on road. However, the ordering of effects in response to changes to the complexity of interface design was the same. For example, the number and duration of off-road glances increased with increasing number of interface elements, and smaller targets attracted longer off-road glances, in both the road and simulator studies. The work demonstrates good relative validity for the use of medium-fidelity driving simulators for HMI-visual distraction testing, supporting their application in this context, and adds to the literature regarding the visual demand characteristics of in-vehicle interfaces.