Effects of Environmental Clutter, Head-Mounted Display Clutter, and Head-Mounted Display Transparency on Human Efficiency, Safety, and Mental Demand During Navigation

Objective Explore the under-investigated display attribute of head-mounted display (HMD) opacity and its relationship with display clutter and environment clutter in real-world nautical navigation tasks. Background Effect of overlay clutter is a prominent factor of HMD research, but there are many factors to displaying information, and the role of opacity has seen little empirical investigation. Method Thirty participants performed a realistic nautical navigation task in a virtual environment with obstacles, navigating a small speedboat that rendered navigational information that replicated an HMD interface. The display interface was manipulated by the amount of information present (clutter) and the level of opacity. Environmental obstacles were varied in their number. Participants were evaluated on completion time of the tasks, proximity to obstacles, and mental demand. Results Participants performed the task faster when there were more islands, especially in transparent displays. Hazard proximity increased when the environment had more islands and while navigating highly cluttered displays. Increased proximity to hazards occurred only when the display was opaque and highly cluttered. Mental demand followed the same pattern as completion time. Conclusion The study revealed preliminary findings that high-cluttered environments should be navigated with more transparent displays and less display clutter. Application The data from the study highlights the relationship between display opacity, display clutter, and environmental clutter. This provides a foundation upon which more work can ask more complex questions about these relationships and how they can impact navigational efficiency.