One of the nastiest things VR can cause is nausea, discomfort and even simulated food poisoning (more on that later from personal opinion). What I want to discuss is what I learned and what to do and avoid so that you the developer don’t cause nausea to yourself or your players.
- Avoid fast jerky movements that are not player initiated. This causes the inner ear data and eye data to go out of whack, which then in turn causes nausea. Unfortunately fast jerky movements are present in driving games, especially when you jerk the steering wheel, crash, run over rough terrain. I have tried different people on this and found that even the most hardcore track junkies succumb to the nausea.
- Keep your frame rates up. Nothing breaks presence faster than constant dipping of frame rates or extended dips of frame rates. People can easily see judder and frame rate drops because it causes a “glitch in the matrix” type of effect. When something so immersive suddenly behaves odd it reminds the user that they are just in a VR environment. Dipping below frame rate every few seconds is fine as long as it is not too often or long enough. Use diagnostic tools to detect these dips because as a developer we tend to tune these out or become so used to them. Trust the tools!
- In contrast to fast jerky movements, slow undulating movements will cause just as much nausea. The perfect analogy would be the swaying of a medium sized boat on a relatively active water. People who don’t usually get seasick are just as susceptible to this as those who are. This all goes back to the liquid in your ear not matching visual cues.
- Involuntary movement in a tight environment. An example of this would be putting a player on a dolly in a narrow corridor with lots of detail and objects and start slowly moving them down the hallway. If not done right the user can feel like they are being whisked away at an unnatural pace, which can cause a floating feeling(something you really want to avoid in these grounded gravity environments). This type of movement is not as bad in low detail environments or paired with a type of blur. Big open environments are not as susceptible to this.
- How I got myself virtual food poisoning. So I was working on VR and for some reason I was getting low frame rates all day. It only slightly bothered me because of the tolerance I have built. But that day we also decided to go get burritos from a taco truck. The burrito was not the best but it was not the cause of my food poisoning cause 3 other people had the same one. The thing that took me over the edge was when I resumed VR development the burrito smell of meat and raw tomatoes stuck to my hand which I used to hold the HMD up to my head (its faster than strapping it in everytime). So within 30 minutes of doing that I started developing a massive headache which I tried to combat with pain killers to no avail. One hour later I had my wife pick me up from work as I was in no shape to drive myself home. My body immediately shut down when I got in the car and I slept for the 40 minute ride home. Upon getting home I crawled into bed for another 2 hours and to my astonishment I woke up feeling perfectly fine. This has never happened to me before for any food poisoning as the effect lingers for the whole day for me. So yeah, I chalk that up to my body being tricked that it was being poisoned and did some reactive measures to protect me.