As Virtual Reality (VR) continues to gain momentum toward wide-scale adoption both for individuals, and in the enterprise setting, one blemish remains constantly alongside it. That is the concept of people feeling the effects of motion sickness or vertigo while viewing VR content. And to be clear, we’re not talking about the feeling of Keanu Reeves “Whoa!” right after a VR headset is put on – that fades away almost immediately. We’re referring to the longer-lasting symptoms people refer to as motion sickness or vertigo.
Feelings of motion sickness in VR is one of those things where a little knowledge beforehand can be quite powerful. And with the right content executed in the right way can be minimized if not totally avoided by most, if not all, who put on a headset.
We’ve all seen the TikTok of Grandma wearing a VR headset and taking her first VR Roller Coaster ride. She’s screaming her head off while other family members gather around her in a state of paralysis brought on by acute belly-laughter. Sure, it’s all in good fun. And rest assured no Grandmas were harmed in the filming of said video. But this principal is key to understanding the first of three critical factors for those who may be susceptible to feelings of motion sickness while in VR.
FACTOR #1 : OUR BRAINS
The first reason people may experience it has to do with the VR content specifically and how the perception of that content is interpreted by our bodies – most importantly our brains. As is widely known our inner ear is responsible for our sense of balance, or if you prefer the 15-cent word-equilibrium. Aside from taking care of the all the automatic functions to keep us alive – you know like breathing – our brain does another pretty amazing trick. It takes the input from what our eyes see, and combines that with data from the inner ear.
These two things (and probably a bunch of other things) tell us that we’re moving or not and hence when to feel motion or not. So one of the main instances of motion sickness in VR is the Roller Coaster ride. Sure, this was once the low-hanging fruit for all the content producers to showcase VR as a medium. The simple fact that VR is so convincing visually plays into people’s negative reactions to situations like the roller coaster. It’s as simple as the eyes reporting they’re seeing movement to the brain. The brain then checks with the inner ear who reports there is no movement, and (insert John Madden BOOM) that discrepancy is what makes us feel woozy. So, if you’re a VR content creator and you’re producing content that creates this vestibular variance, just STOP! Don’t make me tell Grandma on you!
FACTOR #2 : FRAMES PER SECOND (FPS)
The second area where motion sickness may be noticed by some also falls directly at the feet of content creators once again. That is the notion of Frames Per Second or FPS. Remember those little flipbooks we used to sketch of the little stickman running? It’s sort of like that. Think of each of those little pages as a frame. Our TVs, computer monitors, and yes even VR hardware displays content much like a flipbook – in frames. VR hardware has limits for performance. And sure, it’s the content makers’ responsibility to find those and push against them. The trouble is that some content producers tend to play a little fast and loose with the issue of frame rate – oftentimes at the cost of the user. At times certain content may require more processing power than a device can muster. At that point the device or app has no choice but to drop a frame (i.e. show less little pages) at times OR simply crash which no one wants. The feeling of frame droppage can sometimes cause a person to feel wobbly or a little dizzy. Again, back to that pesky brain and our eyes’ need to constantly make sure we’re seeing everything correctly. When a frame or two is missing, whether we’re conscious of it or not, our brains notice. And it’s the brain’s need to fill in that gap that causes the negative feeling. On devices like the Meta Quest 2 for instance, a frame rate should never drop below 70 fps at an absolute minimum. Desirably, the lowest frame rate should really be 90 fps to be super safe.
FACTOR #3 : VR HARDWARE
The third reason motion sickness could be experienced by some is very simple and mechanical as it relates directly to the VR hardware itself. And that is tracking. Tracking is the term that corresponds to how the headset (and controllers) maintain their orientation in the virtual environment based on their location in real life. This is done in various ways. The HTC Vive Pro for instance uses external infrared emitting devices called “base stations” to create an IR field whereby the actual hardware uses its dimpled design to reflect the IR light and broadcast where the headset and controllers are. This is called outside-in tracking.
The Meta Quest 2 uses (4) cameras mounted in the headset to track that hardware. This is called inside-out tracking. Tracking has made a lot of advancement over the years but remains incredibly important to creating a good experience. If tracking is lost or interrupted, the image in the headset will stutter and/or freeze in such a way as to possibly create dizziness or disorientation. The good news about this is that it’s a very simple issue to address. First, don’t purchase or use a device with notorious for having tracking issues (not pointing fingers or mentioning names here). Second, know the ins and outs of what creates a positive tracking environment. So, if you’re using a Vive, make sure there’s no objects in the way of the base stations and they’re facing each other adequately. Or if you’re on Quest 2, make sure there’s plenty of light so the cameras can see. These best practices should eliminate about 90% of tracking issue-causing motion sickness while in VR.
BUT WAIT, THERE'S MORE…
The last issue to discuss is less a cause of potential motion sickness in VR and more of a reality. It’s really about the people that are out there using VR. For whatever reason it would seem the older a person is, the more often it is they could experience these feelings. Data has shown during the aging process, people may fall prey to a condition like vertigo. Surprisingly it doesn’t have to do with the fluid in the ear solidifying over time as many have thought. Instead, it is brought on by circulatory changes in the very small blood vessels in the ear. This explains why your 10-year old nephew can spend about 6.5 hours playing Gorilla Tag without a break. But if you’re a person that is affect by actual vertigo, you’re going to know that and subsequently VR may not be a good fit. Second, there is a certain portion of the population that just can’t do VR comfortably. Period. It’s just that simple. These are people that for varying reasons simply cannot participate without having these negative feelings. Now, is this a large segment of the population? Absolutely not. It’s certainly not a large enough segment to deter the exciting technology from widespread adoption. It’s closer to SCUBA diving. There is a certain percentage of people who simply are not able to equalize their ears versus the water pressure (I know! Ears again right?!). But hey, maybe they could SCUBA in VR! Whoa, that’s Meta concept! (See what I did there?)