Institute of Transportation, MOTC

       Advancements in technology have introduced mobile devices and in-car systems that offer not only navigation and entertainment but also raise concerns about distractions. However, there's a noticeable lack of research when it comes to power-two-wheelers (PTWs). The primary objective of this study is to comprehend how PTW riders' eye movements and driving behavior differ when utilizing different navigation methods. We employed a mixed experimental approach, considering the type of navigation as a between-factor and whether navigation was used or not as a within-factor. We examined visual, auditory, and audiovisual navigation, comparing these scenarios to a memory-based scenario. We quantified mental workload through questionnaires and also analyzed gaze position, duration, and cycle duration across scenarios. To assess safety performance, we used multilevel regression. In comparison to the memory-based scenario, all navigation modes led to reduced non-forward gaze duration. Notably, auditory navigation performed the best. Concerning the sight distance to stopping distance ratio, the memory scenario exhibited superior performance, while all navigation modes negatively affected this ratio. Overall, auditory and audiovisual navigation outperformed the others, auditory navigation excels in terms of safety indicators, while audiovisual navigation holds an advantage in terms of efficiency. However, due to the difficulty in estimating cognitive distractions, it's not easy to definitively determine which one is superior. Additionally, we made an important observation regarding leftward maneuvers in PTWs riding. Whether in terms of psychological workload or eye movement and behavior, left turns required greater attention. This highlights that leftward maneuvers are more complex for PTWs riders compared to right turns.