The effects of age, interface modality, and system design on drivers' attentional demand when making phone calls while driving on a limited-access highway

January 2019

In-vehicle information systems that allow drivers to use a single voice command to complete a task rather than multiple commands better keep drivers' attention toward the road, especially compared with when drivers complete the task manually. However, single voice commands are longer and more complex and may be difficult for older drivers to use. The current study examined the glance behavior, workload, and driving performance of drivers ages 20–66 years when they placed a call using their hands or voice with the Chevrolet MyLink or Volvo Sensus information system during highway driving. In general, as age increased, drivers took longer to complete phone calls, reported greater workload when using voice commands, and made significantly more off-road glances lasting longer than two seconds when placing calls relative to younger drivers. Both the voice-command systems of MyLink and Sensus increased the proportion of time that drivers were looking at the road when calling compared with manual phone calling, but the relative increase was greater when using MyLink's single-voice-command system compared with the multiple-command system of Sensus, and this advantage grew as drivers aged. The findings indicate that placing calls while driving using voice commands helps drivers of all ages keep their attention toward the road better than doing so manually, and that, contrary to expectation, using a single-command system like MyLink's worked better than a multiple-command system like Sensus for older drivers as well as younger ones.