Video passthrough headsets cause cautious movement and eye strain
Passthrough Rigidity: The Behavioral and Visuomotor Costs of Mediated Perception
Human-Computer Interaction
Summary
Using headsets that show the real world through video screens, instead of naturally, makes people move their heads more carefully and look around less freely. The researchers studied people doing a hand-eye task wearing such headsets and found that users slowed down their head movements and focused their eyes more narrowly. This led to worse task performance and feelings of eye strain and mental effort. The authors call this the "Passthrough Rigidity" effect, and it helps explain why even with better headset technology, people still feel discomfort.
What this means in practice
- •For xr hardware designers: Adapt head-mounted display designs to reduce motor caution and eye strain caused by current video passthrough systems during complex interactions.
- •For ergonomics consultants: Develop assessment protocols and guidelines for evaluating user comfort and biomechanical efficiency in mediated reality environments based on eye and head movement metrics.
Authors
Markus D. Solbach, Mohit Goyal, Sakar Khattar, Jayant Varma, Bjorn Vlaskamp, John K. Tsotsos, Konstantine Tsotsos
Abstract
Broad public adoption of head-mounted displays using video passthrough remains elusive despite significant market investment. A precise understanding of why users experience persistent discomfort even as hardware factors such as resolution and latency have dramatically improved remains an open issue. This paper investigates the impact of viewing the world through video passthrough systems on human behavioral and physiological patterns through a large-scale multimodal study. We developed a novel protocol to capture synchronized oculomotor, kinematic, and physiological data during a block assembly task requiring complex hand-eye coordination. Using a within-subject design (N=110), we evaluated both natural and passthrough viewing conditions. Our results reveal a four-fold suppression of rotational head velocity and a pronounced decoupling of head-gaze coordination. This suggests motor caution being employed as an adaptive strategy - which we term "Passthrough Rigidity". This phenomenon appears to shift the information-gathering burden to the oculomotor system, resulting in significantly longer fixation durations and restricted visual search patterns. These kinematic shifts directly correlate with poorer task performance and measurable physiological cost, evidenced by a significant reduction in blink duration and increased reports of ocular strain and cognitive load. We conclude that current passthrough implementations induce a measurable shift from flexible exploration to motor caution, where task performance is preserved at the cost of user comfort and biomechanical efficiency. These findings provide a novel quantitative framework for evaluating and improving future XR devices, establishing that resolving "comfort" for passthrough requires addressing the deep-seated biomechanical compensations caused by mediated perception. Data available at https://data.nvision.eecs.yorku.ca/Passthrough