Safety impacts of using smartphone voice control interfaces on driving performance

Distraction from the use of mobile phones has been identified as one of the causes of road traffic crashes. Voice control technology has been suggested as a potential solution to driver distraction by the manual use of mobile phones. However, new evidence has shown that using voice control interfaces while driving could require more from drivers in terms of cognitive load and visual attention compared to using a mobile phone manually. Further, several factors that moderate the use of voice control interfaces, for example, usability and acceptance are poorly understood. Thus, the current study aims to investigate the safety impact of using voice control interfaces on driving performance. A preliminary study, an online survey and a driving experiment were conducted to investigate how drivers interact with smartphone voice control interfaces and their effects on driving performance. First, the usage pattern of voice control interfaces while driving was explored using focus groups and interviews (preliminary study) and an online survey. Next, 55 participants completed a simulated driving task that utilises a valid and standardised method called the Lane Change Test (LCT). The purpose was to measure degradation of driving performance due to the concurrent performance of secondary tasks; either contact calling, playing music or text messaging task. These secondary tasks were identified as common tasks in the survey of the pattern of use of voice control interfaces while driving. Secondary tasks were performed in both visual-manual and voice control modes with either an Apple or a Samsung smartphone. Data on eye glance behaviour, workload and, usability and acceptance of the voice control interfaces were also collected. Findings support the view that interacting with voice control interfaces while driving reduces distraction from visual-manual interfaces but is still distracting compared to driving without using any devices. Texting was found to degrade task and driving performance regardless of control modes and phone type. Moreover, poor system performance leads to low acceptance of voice control technology. Smartphone voice control interfaces have an apparent advantage over visual-manual interfaces. However, they still can impose some elements of distraction that may have negative implications for road safety