In-vehicle interactive systems are widely used in modern vehicles. While these systems serve various purposes, they are also potential distracters for drivers. In this study we investigated the effect of in-vehicle spatial distractions on driving errors and driver gaze behavior by developing an experimental paradigm named, "Direction Following in Distracted Driving - Spatial: Simultaneous and Sequential (D3-SSS)." Twenty-seven drivers voluntarily participated and were required to drive an instrumented vehicle on a two-lane test-track, following directions shown on direction signboards. While driving, drivers were required to respond to in-vehicle spatial distracting stimuli presented to them through a monitor attached to the dashboard. The drivers were randomly assigned to in-vehicle spatial-simultaneous and spatial-sequential distraction conditions. Our results demonstrated that, in comparison with spatial-sequential distractions, there were shorter eye fixation durations and fewer eye fixation counts on areas of interest (AOIs) during spatial-simultaneous distractions. We also found that drivers committed more driving errors during in-vehicle spatial-simultaneous distractions than when these were not occurring. In conclusion, drivers committed more slips than lapses, and spatial-simultaneous distraction was more detrimental to driving performance than was spatial-sequential distraction.
Keywords: driving errors; fixation durations; gaze behavior; in-vehicle distractions; lapses; slips.