Scientists are confirming that virtual reality systems can trigger a new form of motion sickness in users, especially in women.
VR headset users are reporting that using the headsets makes them feel sick. This phenomenon has even gained a name: VR sickness.
Motion sickness has been around for a very long time. The prevailing theory on what causes motion sickness has something to do with vision and the vestibular system in your inner ear. If you're in a moving car and you get motion sickness, it's because your vision and inner ear aren't in sync. Your vision sees the stationary inside of the car, but your inner ear knows that your body is in motion.
In virtual reality, the situation is reversed but the effects are the same. Your eyes see that you're “moving” through the virtual world you're in. However, your inner ear knows that your body is actually stationary.
Another theory on the cause of motion sickness points to being in an unstable environment. According to the postular instability theory, the motion of a car or a ship disrupts your balance. Motion sickness happens as your body fights to regain control of that balance.
This theory can also explain VR sickness. While you're just sitting down, your eyes see that you're moving around. You'll instinctively react to visual cues in virtual reality the same way you'll react to the cues in real life. That may be what's causing VR sickness.
Thomas Stoffregen, a kinesiologist, is a proponent of this theory. He is using it to explain why women are more prone to motion sickness than men. According to Stoffregen, people make unconscious movements in order to stay balanced. This is called postural sway, which is a measurable indicator of the propensity for motion sickness. Postural sway also differs in men and women.
For his experiment, Stoffregen measured the postural sway of 72 participants. The participants then had to play two games for 15 minutes each. The first game didn't yield significant results, but the second one did. The second game showed that 78% of the female participants felt sick, while only 33% of the male participants did. Stoffregen found a significant difference in the postural sway measurement of those who got VR sickness and those who didn't.
Visual acuity may also cause VR sickness. In another study on VR sickness susceptibility, 72 participants with 20/20 vision watched videos in VR headsets for 20 minutes. 75% of the female participants weren't able to last 20 minutes before feeling sick, compared to 41% of the men.
It seems that having better visual acuity makes people more prone to suffering VR sickness. Note that other studies have found that women have better visual acuity than men.
There are many other studies and many other theories on what kind of people are more prone to motion sickness. What's increasingly clear, though, is that being prone to motion sickness is going to make virtual reality systems a nightmare.
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