jason-jeraldWhen people dream about what they want to do in VR, it inevitably involves actually moving around within a virtual environment. But VR locomotion triggers simulator sickness in a lot of people, and solving it is one of the biggest open problems in virtual reality. NextGen Interactions’ Jason Jerald wrote a comprehensive summary of much of the pertinent academic research about VR in The VR Book, and in Chapter 12 he summarizes the five major theories of what may cause simulator sickness.

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I had a chance to catch up with Jason after he taught a class about Human-Centered Design for VR at the IEEE VR conference, and he explained each of the five different theories that may cause simulator sickness including the Sensory Conflict Theory, Evolutionary Theory, Postural Instability Theory, Rest Frame Hypothesis, and the Eye Movement Theory.

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See Also: 7 Ways to Move Users Around in VR Without Making Them Sick

Jason also talks about ways to mitigate simulator sickness including implementing different viewpoint control patterns, using a cockpit, providing a leading indicator of movements, walking in place, vibrating the floor, reducing texture complexity, and limiting optical flow in the periphery.

He also discusses the tradeoffs for varying the Representational Fidelity ranging from stylized to photorealistic, and the Interaction Fidelity ranging from abstracted to literal and natural gestures. While there are ways to mitigate some of these causes of simulator sickness for VR locomotion, some of them remain open problems yet to be solved by the wider VR community.

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Kent Bye
  • Seerak

    Acceleration G’s are a big part of this issue. I tried a friend’s car race simulator in VR, and we were on Laguna Seca, which has a famous S-curve in it with a significant drop in height. I was fine all the way around the course, but every time I came into that S-curve too fast, my brain really wanted to know why there weren’t any G-forces. I’m relatively resilient to motion sickness in games (but, oddly, not handheld “shaky-cam” movies, may their directors puke in hell forever), but that S-curve was 0-to-uh-oh in 2 seconds.

    • DiGiCT Ltd

      Yes you are right, g forces are really missing and it can give motion sickness or even losing balance in the real world.
      Had similar test results on this subject, although some even dont give motion sickness but i would rather say it does not feel real anymore like those roller coasters in VR is the best example of not getting sick but just feel strange and unreal for most people.
      The most sick by missing G and make you totally sick in most cases is however the game “WarThunder” by using an airplane and do several 360 rolls and trying to follow an other player in air battle by outmaneuvering others.
      I felt sick from that several hours, even did not want to put my hmd on anymore for that day,

      Lost a lot of time as i still needed to work on my own VR project which i really felt not able to handle the HMD for a while.

  • Raphael

    You left out one cause: attention-seeking. It’s very trendy to announce to everyone that vr made you fall off your chair and vomit.

  • Andrew Jakobs

    I always hear people bitch about resolution and framerate, but never about incorrect setup lenses and focus, those are way more responsible for motion sickness than resolution or framerate.. try running around with prescription glasses that are not for you, good luck on not trying to vomit….

    • James Friedman

      Good point

    • Bob

      Yes, companies that say its just theories are clueless.

    • Ricardo Broeders

      It’s not only the hardware. Software as well. I real life we blur and sharp objects to get a realistic view of where we are. So we can focus at different kinds of objects and not all at once. In VR most of the time everything is sharp background and everything in front of you. Your eyes have to get used to that as well because everything is so close in front of your eyes.

      • brandon9271

        Eye tracking and depth of field should solve that issue. If only a few things were in focus the brain may be better fooled.

    • DougP

      Re: “but never about incorrect setup lenses and focus”
      I don’t understand this.
      In current consumer VR the is no setup of lenses & focus. These are just fixed in-place.

      Can you explain what you mean by this?

      • Andrew Jakobs

        And that’s exactly what’s wrong with it, fixed lenses/focus.. nobody has the same eyesight, and therefore it’s imperative that one should be able to set the focus and position of the lenses correctly, why do you think an optician has such a wide variety of lenses and takes his/her time to pick the correct ‘settings’ for the person so he/she sees everything sharp and in focus with their new glasses… Have you ever walked around with prescription glasses that aren’t correct for you? if you have, you know that it’ll give you headaches and makes you feel nauseous, exactly the same as a lot of people describe after having put on a DK2 or other VR glasses where you cannot correctly setup the focus/lenses..
        I have an old VFX-1 which is only 320×200 per eye and only has 35fps refresh, and yet I have totally NO motion sickness using that HMD, but that HMD let’s me setup the focus and lens positions correctly, I also have a VR920 which also lets you setup the focus/lens positions, it has 640×480 per eye with a refreshrate of maximum 60fps, again NO motionsickness whatsoever.. And then there is my DK2, no way to set the focus or lenspositions, and it has a higher resolution and a faster refreshrate (75fps), and guess what, after a few minutes I get motionsickness..
        I haven’t had the chance to test a CV1 or a Vive, but at least you can set the horizontal lensposition manually, so that should take care of some problems, but there is no actual way to set the focus.

        • fuck you

          is this dude seriously comparing tech from the 90s to recent stuff? lmao!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! what is next? you ll compare a horse to car? saying how better it is because it is green or something? lolsss the only thing the VFX-1 has that these recent HMDs don’t is that it’s worse in EVERY aspect, optics included, people bitch about resolution and framerate because it is the only thing a sane person would moan about, the image quality is indeed low and inferior to a regular display but certainly a billion times better than an old VFX-1, all your claims are anecdotal and delusional, the VFX-1 is no better than a rotten potato

          • Andrew Jakobs

            oh please, get you f-ing head out of your ass. The VFX-1 headset was even more comfortable than any of the current headsets, and it fit everybody, it had flipup visor and excellent headphones. yes the electronics are ancient compared to what we now have, but in a sense it was even more advanced than any of the headsets we have now. And I don’t say the actual optics are better, what I say is the way they handled the optics by letting you manually focus and position the lenses which is what makes it much better (way to do it) than the crap lenses the current headsets have, especially the fresnel lenses.
            You’re a moron, and the fact you use ‘fuck you’ as your name says more than enough…

          • fuck you

            so u think the people who made the HTC and CV1 didn’t include focus adjustment because they are dumb? they did it for a reason and it only favors the user u retard, if you have a prescription u’re supposed to wear your OWN glasses/contact lenses under the HMD, it’s virtually IMPOSSIBLE to have an universal fix within ONE device to every person on earth disabled of the eyes, NO device EVER did that, so having focus adjustment is USELESS for both the people who don’t need any glasses and some of the ones who need, not including anything is the right thing to do

            also at least in the universe i live in both of them got inbuilt headphones (that are optional thank god) and both of them let users change the IPD, the only headset that doesn’t is the OSVR that doesn’t even has a consumer version yet, and the reason for that is that not only the whole device is hackable how the optics are so good that almost the whole screen is usable so they didn’t even saw the need to include the damn thing lmao!!!!!!!!! but the box is too small for the user to wear glasses so they included the useless focus adjustment that makes u wet just like GearVR did

            and i don’t care if it has a flipup visor, mine has straps and it doesn’t restrict me from doing any kind of motion at all, all your claims in favor of ancient technologies are anedoctal, the specs are more than greatly inferior in every and all aspects, and people MUCH MORE prone to get motion sickness when using any of those old models, they are just history, it’s nothing but dishonest to go back in time to compare any aspect of them side by side gratz on being a clown

          • Andrew Jakobs

            Funny, as I had ZERO motion sickness with my VFX-1 in any game, even rollercoasters, but I can’t wear my DK2 for very long without getting motion sickness.. And motion sickness wasn’t the problem on the old VFX-1.

  • James Friedman

    I have only felt sick once playing Windlands, bouncing around like a mad man with the comfort setting turned off. Wow is that fun though. That game gave me a tickle in my stomach.I was seated playing on the rift. Not sure if I would of felt different standing.

    • DougP

      Re: Windlands

      I love Windlands. I play it on my Vive and ONLY play it standing up.

      I’m must be a “lucky one” as I’ve never felt motion sick or “VR sickness”.
      However, in Windlands only… (again while playing standing) I’ve felt a couple of times where I flew through air & crash landed (trying to land on tree but falling) where legs went little wobbly trying to *catch*/*right* myself.
      Never felt sick tho’….just that fun rollercoaster stomach moment & wobbly legs. Laughed & loved it.

  • ZenInsight

    Motion sickness occurs because in real life and you look at the distance things in the foreground are actually blurred and appear to be partially doubled. And when you look in the foreground the background is completely blurry. Motion sickness is a visual Focus issue. Until they have a way to track your eyes and where they are looking at so that they can change either the foreground or background to be blurred motion sickness will not completely go away.

    • Raphael

      Hence the nvidia and stanford research vr system using multiple image planes to recreate realistic depth layers.

  • beestee

    The only experience I have had of getting nauseous in VR came from a long session of Adrift…but that is a zero-g environment, so is motion sickness a problem in space as well?

  • yag

    Things should go better with wireless headsets and full 360° standing mode.

  • DougP

    Re: Motion / VR sickness
    I wonder if there’s some correlation between people who are more inclined (or highly susceptible) to motion sickness?
    Most likely VR, in consumer version (90hz/fps & decent res) is too new to have had this studied in depth.

    For example: people who’ve felt sick on a boat, driving winding roads, on a roller-coaster – are they more sensitive to feeling sick in VR?

    I was originally inclined to think it might be more than one thing – motion sickness for some & “VR sickness” possibly more due to technical implementation (low res & low framerates & laggy-tracking). But now that consumer VR is out & I read reviews about games which I have ZERO issue with but the reviewer calls it “puke city”, I’m more inclined to think that some people are just more susceptible.

    [ Selfish side note: I’d hate to see games limited/dumbed-down to be “comfortable for all” instead of having different modes for those who aren’t bothered. For example – I’m not bothered by “traditional locomotion” – pressing on pad to *slide* forward/around like in traditional FPS games while in VR ]

    I’ve seen reviews on steam bashing games saying it makes a person sick. Whilst I can play the same game & have no issue. Seems unfair to the developer. Bad analogy incoming…but it’s like leaving an poor amusement park review online by someone who can’t go on a roller-coaster without getting sick. ;)

    I completely get that there can be technical reasons (see above) which can be due to poor design/optimization/testing, but eliminating these in many games still leaves some (many?) with *sickness* inside VR.

    It will be a bummer if it’s mostly just that some people are just inclined to feel sick, and thus can’t/won’t experience much VR (similar to those who need to avoid roller-coasters)….but worse still if VR games are severely limited (hobbled) to make *everyone* comfortable, restricting experiences for those who could otherwise handle more.

    • brandon9271

      Motion sickness definitely comes in many forms. Roller coasters don’t bother me but being on a boat does. Same thing with being in the back of a car on winding roads. My VR experience is limited to DK1 but it too made me nauseous. I think it was primarily due to latency and screen smearing because i didn’t even have to be moving to feel nauseous. Actually, the lack of positional tracking was also a MAJOR issue as well. Hopefully I’ll get to try a Vive soon.

  • Greg Dietz

    I get no motion sickness at all, which is strange because I get sick while reading in a moving car. I hope developers at least give the option to move around in VR environments with the analog stick because for those of us that don’t get sick it feels a little restricting to just teleport around.. besides that’s so unlike ACTUAL REALITY that it really ruins the experience for me :/