User study design
We introduce a comprehensive protocol focused on key VST use cases to holistically assess visually-induced discomfort and cybersickness in VST HMDs. We then use this to compare our GAP algorithm to DP.
To achieve reproducibility, repeatability, and real-life relevance, we began with tasks identified in the literature, tested them in a pilot study, and iteratively refined the task nature and duration based on participant feedback. A total of 25 consenting participants with normal or corrected-to-normal vision completed the tasks for the study. Each participant experienced all conditions including NV, DP, and GAP, allowing for a direct comparison of each participant’s experience.
We devised our protocol focusing exclusively on passthrough-based real-world interactions and ensured no virtual elements were visible to participants. The tasks were inspired from fundamental real-world XR applications such as working with laptops for productivity, navigation in the physical world, and interaction with real-world objects. They emphasized user head motion while necessitating inspection and spatial awareness of the physical world. Specifically:
- Typing: This task was chosen to reflect emerging applications in productivity and to effectively engage both visual and motor components. Participants typed on a physical Dvorak keyboard, chosen because it required frequent gaze shifts between the keyboard and a laptop screen.
- Navigation: The realistic and holistic use of a VST HMD involves navigating physical spaces, avoiding obstacles, and interacting with real-world objects. We designed a navigation task where participants collected and dropped off 10 numbered cones, one at a time, into a designated drop zone. This task emphasized geometry perception and required multi-directional movements.
- Interaction: This task was designed to simulate common assembly tasks requiring both motor and cognitive skills. Participants assembled large 24-piece jigsaw puzzles by retrieving and working on only one batch of 8 puzzle pieces at a time within a rectangular frame marked on the table. The large puzzle size was selected to accommodate head motion which is often associated with motion sickness.
To measure cybersickness, we used the Simulator Sickness Questionnaire (SSQ), which categorizes symptoms along four subscales: nausea, disorientation, oculomotor, and total severity. Participants filled out the SSQ before and after each task to isolate the cybersickness experienced in each mode. In addition to the SSQ, participants rated their general discomfort on a scale of 0 to 10 after completing each task. Finally, participants provided qualitative feedback on their experiences at the end of each task.