Visual search characteristics when using a navigation system focusing on driver age, display size and environmental illumination

Navigation systems are a fast and efficient source of road information to drivers. However, navigation systems can distract a driver, often causing poor driving performance, increasing the risk of road accidents. In this work, the effect of driving environment (in urban and rural areas), navigation system display size (large and small), environmental illumination (day and night), and gender on young driver visual distraction by the GPS display and driving safety were investigated. The study was conducted on a driving simulator, where variables related to mental workload, driving performance, driving safety and eye movements were observed. This work was divided into three papers. In the first paper, mental workload data were collected with the NASA-TLX (NASA Task Load Index). In the second paper, driving performance and driving safety data were collected through driving simulator software. In the third paper, visual distraction by the GPS display, and visual search data were collected with an eye-tracking system. Twenty subjects, ten males and ten females, between 18 and 29 years old, participated in this study. All the metrics used in this study were analyzed using a repeated-measures analysis of variance (ANOVA) model. The first paper showed that drivers had higher overall task workload in the urban area and at night when compared to the rural area and daytime driving. Also, it showed that the drivers were more distracted by the GPS display in the urban area and with the small GPS display. The second paper showed that in urban areas the use of a small GPS leads to more navigation errors. Also, in the urban area more accidents by male drivers during daytime were found. In rural areas, male drivers at daytime tended to make more speeding violations. The third paper revealed that the small GPS display created a higher distraction in terms of average duration of gaze and total duration. Surprisingly, daytime driving generated a higher level of distraction by the GPS display. Also, the visual search approach used had a wider viewing pattern during daytime driving. These findings indicate that driving in urban area creates greater overall workload and distraction by the GPS with the small GPS display creating greater distraction, degrading the driving performance in urban areas. Although, while driving during daytime showed a higher level of distraction by the GPS display, it produced a lower overall workload and a wider visual search. This finding might be due to driver tendency to underestimate the need to keep their eyes on the road while driving when in relatively easy driving conditions. Moreover, young male drivers tended to underestimate speeding risks in both the rural and urban areas during daytime driving, perhaps due to their underestimating risks in the relatively less complicated driving conditions.