Original title: Quantifying and characterizing vergence-accommodation-conflict-induced cybersickness in immersive environments
Matthew Johnson, Sujal Bista, Sida Li, Jonathan Heagerty +4 · September 2026
Virtual reality can make most users feel sick with headaches, nausea, and blurred vision. One suspected cause is vergence-accommodation conflict, or VAC. This eye mismatch happens when your eyes turn toward an object at one distance while your lenses must focus on a screen at another distance. Researchers tested how this mismatch causes cybersickness. They showed people a moving sphere that shifted in and out of the Zone of Comfort, the area near the focal plane where the mismatch is small. While participants watched, the team recorded their electrical brain activity using sensors. They found clear brain changes linked to this mismatch. Certain fast brain waves dropped in front areas of the brain, while certain slower waves decreased in back areas. These brain signals could serve as a real-time way to track sickness, helping creators monitor and reduce discomfort so more people can enjoy virtual headsets.
Imagine trying to take a photo with a camera that has a fixed lens—you can only focus clearly at one distance, and moving the subject blurs the picture. Now imagine your eyes in a VR headset: they must focus on the screen at a fixed distance, but virtual objects appear to move closer and farther, straining your eyes and causing headaches. Here, the researchers measured brain waves to detect when that strain occurs.
If you've ever felt nauseous or headachy in VR, you've experienced cybersickness. This research shows that a specific cause—the conflict between where your eyes focus and where they converge—can be measured in real time using brain waves. That opens the door to systems that detect and reduce sickness before it ruins the experience, making VR usable for more people.
The authors caution that the EEG changes are candidate correlates, not a VAC-specific signature, because the baseline condition did not match the VAC scene and ocular/muscle artifacts could not be fully excluded. The study also only tested one type of visual stimulus (a moving sphere), so it is unclear if the findings generalize to other VR content.
Ask anything about this paper. Answers come from its abstract, and say so when the abstract doesn't cover your question.
Quantifying and characterizing vergence-accommodation-conflict-induced cybersickness in immersive environments — Matthew Johnson, Sujal Bista, Sida Li et al. — Virtual Reality — doi:10.1007/s10055-026-01484-2
Abstract licence: CC BY
Explanation generated by Synthesis from the abstract — it is not the original paper.