There's a fundamental misconception people have which is being demonstrated in this topic, and why what people experience shouldn't be called motion sickness. The things that cause motion sickness in people, are not the things that cause VR sickness. A predisposition to getting car sick does not mean you are predisposed to VR sickness.
Really, what people experience are a variety of problems that all have very similar symptoms, that collectively fall under an umbrella term of "VR Sickness." This includes the usual feelings of nausea, but I've also seen people have reactions akin to having a migrane.
To put it simply before I explain further, people prone to motion sickness aren't necessarily prone to VR sickness, and vice versa.
Now, for some of the causes of VR sickness that have been identified:
-The big one is vestibulocochlear disconnect. This is when your eyes report motion that your inner ear does not. The juxtaposition can cause a feeling of nausea in many people. Linear motion forward is usually alright for most people susceptible to this, but lateral rotation is a killer. Teleportation solves this problem entirely, but some people do not like that gameplay mechanic. Other comfort options, like progressively dimming the edges of your vision, can also mitigate this.
-Flicker perception was another big cause of VR sickness. For the vast majority of people, the threshold where they stop being able to perceive the flicker of a screen's refresh is 75 hz (which is why the DK2 ran at that frequency), so most people can't perceive flicker on the consumer headsets. However, some people are extremely sensitive to flicker, and can perceive it even at 120 hz, which can cause nausea.
-Finally, strenuous motions in VR are strenuous the same way they are IRL. If you're one to blow chunks if a plane barrel rolls IRL, then doing that in VR will likely make you sick.
The real solution to VR sickness is to simply offer as many comfort options as possible. The concept of "VR legs" is largely a myth, there are many people who cannot and will not ever acclimate to the things about certain locomotion systems making them sick. The only people who will push onward in an attempt to gain "VR legs," which might never form in the first place, are people who were sold on the technology before even trying it, which isn't the correct way to drive VR adoption.
