THE MISMATCH
Eyes and body disagree
Cybersickness, a form of motion sickness linked to headsets, occurs when what you see doesn't match your body position, says the Canadian Association of Optometrists.
What makes it worseWHAT THE VR RESEARCH SAYS
When your eyes
and ears disagree.
Your eyes say you're moving. Your body says you're sitting still.
See what makes it worse
15.6%dropped out of VR studies
- Mind the mismatch
- Pick calmer content
- Take it in short spells
- Comfort is part of the design
Many people feel dizzy, queasy or strained after time in a virtual reality headset. Researchers call it VR sickness or cybersickness, and studies point to two causes: a mismatch between what you see and what your body senses, and screens that sit at a fixed focus.
Updated
THE SHORT ANSWER
A mismatch
your brain notices.
Eyes report motion, the body reports none.
The screens fix your focus at one depth.
THE FOCUS
One screen, many depths
Your eyes turn to aim at near and far objects, but in a stereo display they focus at a fixed screen depth. A 2008 lab study linked this conflict to fatigue and discomfort.
See the numbers
THE DOSE
Content and time count
A review of 55 studies found gaming content scored worst and scenic content lowest. Most headset makers also carry warnings for children.
What the guidance saysGeneral information only, not medical advice. For advice about your own health, speak to a doctor, pharmacist or other qualified health professional.
WHICH SESSIONS SCORE WORST?
How queasy
does VR get?
Pick a situation to see its average score on the Simulator Sickness Questionnaire (SSQ) in the 2020 review. Higher means more symptoms; the bar shows how high.
From Saredakis et al. (2020), a meta-analysis of 55 head-mounted display studies.
TWO NUMBERS WORTH KNOWING
Not everyone
finishes the session.
One figure for who gives up,
one for the symptom that leads.
15.6%
Average share who quit because of VR sickness
Across the experiments that reported dropouts, an average of 15.6% of participants left because of VR sickness. Some studies using gaming content reported dropout rates of 44 to 100%.
DROPOUTS · 46 EXPERIMENTS
23.5 SSQ
Pooled disorientation score, the highest subscale
Disorientation scored above oculomotor symptoms (17.09) and nausea (16.72). That differs from travel sickness, where nausea usually leads, and points to dizziness, blurred vision and difficulty focusing.
SYMPTOMS · 55 STUDIES
The review covered 3,016 participants (41% female) and found no sex differences. Stereo headsets may add eye symptoms through the vergence-accommodation conflict.
WHAT THE GUIDANCE SAYS
Easy does it
in the headset.
Eye-care and health bodies offer a few general points. They are not a substitute for an eye examination or a pharmacist's advice.
Read the warnings
Follow the warnings that come with the headset. Most makers include warnings for children, whose vision is still developing.
Limit the time
The Canadian Association of Optometrists advises limiting time spent in the virtual world.
Choose calmer content
In the 2020 review, scenic content scored lowest for sickness and gaming highest.
Keep up eye tests
The same optometrists advise regular comprehensive eye examinations for all users.
THE FOCUSING PUZZLE
Aiming and focusing,
pulled apart.
In normal viewing, your eyes converge on an object and focus at the same distance. A stereo display gives every object its focus at the screen surface, so the two responses must be uncoupled, which can make images harder to fuse.
In a 2008 study with a display that gave nearly correct focus cues, viewers identified stereo images faster, saw depth with less distortion and reported less fatigue and discomfort.
Questions
Questions people ask
What is VR sickness?
Symptoms such as dizziness, nausea, eye strain and blurred vision during or after using a headset. It is also called cybersickness or simulator sickness.
Why does VR make me feel sick?
Cybersickness is linked to a mismatch between what you see and what your body senses. The NHS explains travel sickness the same way: the inner ear and eyes send the brain different signals.
Is VR worse for some content?
Yes. In a 2020 review of 55 studies, gaming content had the highest average sickness score, then 360° videos and minimalist content, with scenic content lowest.
Does VR harm children's eyes?
Little is known about its effects on the eyes. The Canadian Association of Optometrists notes that most makers warn about children, because a child's visual system is still developing.
Are women more prone to VR sickness?
The 2020 review found no sex difference, though it notes earlier research suggesting a higher risk for women and calls for more study.
Where the facts come from
- Saredakis et al. (2020), Factors associated with virtual reality sickness in head-mounted displays: a systematic review and meta-analysis, Frontiers in Human Neuroscience
- Hoffman, Girshick, Akeley and Banks (2008), Vergence-accommodation conflicts hinder visual performance and cause visual fatigue, Journal of Vision
- Canadian Association of Optometrists: Are virtual reality headsets dangerous for our eyes?
- NHS: Motion sickness