Honestly, I can't say I felt any kind of "simulation sickness" the two times I experimented with the Oculus Rift HMD during CES 2013 and E3 2013. If anything, it was a task just getting used to the idea that hey, the mouse no longer needs to be used to look around in a virtual environment. Of course, my sessions were somewhat long enough to get a taste of the technology: for those that use VR for long periods of time, simulation sickness can become an issue.
According to Oculus VR's VP of products Nate Mitchell, simulator sickness is the exact opposite of motion sickness. "In motion sickness there's all this motion but you don't visually perceive the walls and ceilings are moving," he told Polygon during GDC Europe 2013. "This is what creates the conflict that makes you dizzy. With simulator sickness it's basically the inverse. These are all the things you want to avoid as game developers."
The trouble with both is that there are differing opinions about where these conditions originate and what solutions can prevent them from occurring. They're largely misunderstood in the medical community, so developers behind virtual reality HMDs like Oculus VR are going to great lengths to research and solve problems related to simulating environments. Unfortunately, VR is still at its earliest of roots – it may be a long time before most symptoms are resolved.
"This is the sort of thing developers like Oculus need to make," he added.
He listed a number of scenarios that contribute to simulation sickness such as changes in altitude like staircases, backwards or quick lateral movement, minimal shifts to the horizon line, and even head bobbing. He added the team is still debating on whether head bobbing actually provides problems. "I'm of the opinion that head bob is not for us, but it needs more research," he said.
Eventually the budding VR industry will see less and less simulator sickness as hardware and software developers come together and create a standard that will keep simulation sickness-causing triggers from appearing. The problem will likely never be completely eliminated, but at least companies like Oculus VR are working to keep our need to puke into the trash can at a minimum.