The dangers of driver distraction caused by in-vehicle technologies have been widely researched. Since the 1930s and the advent of the first car radios, the variety and complexity of in-vehicle technologies which can distract drivers has grown, and now includes devices such as mobile phones and satellite navigation systems. Each new technology that enters the market has the potential to influence driving behaviour in ways that are difficult to anticipate. ‘Smart glasses’ are an example of one of these new classes of technologies which may affect driver distraction. Smart glasses are multifunctional wearable computers which are worn on the head and typically display visual information to the user through lenses mounted in or near the eye line. Presently, the extent to which smart glasses may positively or negatively affect driver distraction is not understood. On the one hand, they offer the promise of reducing driver distraction in comparison to traditional means of satellite navigation by, for example, having a more sophisticated voice control interface, which has been consistently shown to outperform manual control (Basacik, Reed & Robbins, 2011; Caird et al., 2014); and by displaying visual information near the forward visual field, the time a driver spends with their eyes off the road in order to assimilate navigation information may be reduced. However, they may also present information in a more compelling manner, resulting in additional distraction; or the display may potentially obscure important visual information, resulting in a failure to perceive hazards. This study comprises two parts: a review of current literature on driver distraction related to smart glasses; and an on-the-road experimental study comparing driver behaviour whilst navigating using (1) smart glasses; (2) smartphone-based satellite navigation (satnav); and (3) verbal instructions. The literature review discusses the nature of driver distraction and examines the evidence available, to ascertain the extent to which smart glasses might distract or assist drivers in the primary driving task. Although relatively little research on this technology exists, those papers which have been published are reviewed. The evidence obtained suggests that smart glasses are likely to distract drivers from the activities required for safe driving; however, it is possible that they will do so to a lesser degree than other in-vehicle information systems, in particular handheld smartphones being used for communication. This is due mainly to the use of voice control, which has been shown consistently to distract less than manual interfaces. However, a note of caution must be sounded, as smart glasses do possess the potential to distract from the visual field1 by: masking important road features behind a display; diverting driver attention away from the driving task and onto their display; and/or creating ‘cognitive capture’ in users (the phenomenon whereby drivers focus too heavily on the central forward field and ignore important cues in their peripheral vision). The use of smart glasses when driving must therefore be carefully considered until further research conclusively demonstrates their effect on driving performance. This experimental study focuses on the consequences of having visual information displayed over a portion of the forward visual field. A representative sample of 16 members of the general driving population completed three successive drives on public roads whilst navigating to an unknown destination. During each drive they followed the directions of one of three different forms, or ‘conditions’, of navigation: standardised voice instructions from a driving instructor (i.e. verbal information only), navigation information displayed on a smartphone (the ‘satnav’ condition — visual information only), or navigation information displayed on smart glasses (visual information only). Driving behaviour was assessed using a modified form of the Viennese Driving Test (VDT) (Chaloupka & Risser, 1995) and questionnaires were administered to gather subjective self-reported data from each participant on their experiences of each drive. Results showed, when assessed by the VDT, that drivers were equally likely to commit a driving error when receiving verbal instructions or using either satnav or smart glasses. Furthermore, the number of times an incorrect turn was taken was also recorded,2 and this showed that drivers were equally likely to take a wrong turn when using either satnav or smart glasses, but much less likely to take a wrong turn when receiving verbal instructions. Participant self-reported measures of workload (using the NASA-TLX questionnaire) and their impressions of the drives showed a clear trend for giving verbal instructions the most positive ratings, followed by satnav, and then smart glasses. A log of technical problems encountered during the trial with the satnav and smart glasses was recorded. There were no technical problems with the satnav. In contrast, only one trial out of 16 did not experience some form of technical problem related to the operation of the smart glasses. These problems were related mostly to overheating and loss of Bluetooth connectivity between the smartphone and smart glasses. Reasons for these technical problems are considered. The results of this study suggest that the visual distraction caused by presenting navigation information in the upper right portion of the user’s forward visual field via smart glasses does not reduce driver performance compared to verbal navigation or use of a satnav. On the other hand, participants demonstrated a clear subjective preference for verbal navigation and least preferred the smart glasses tested. The extent to which this was due simply to their unfamiliarity with smart glasses technology is unclear. The study involved a limited number of participants, so further research on this topic is needed if further confidence is to be gained in the extent to which these results can be generalised to the wider population. (Author/publisher)
Abstract