Nobody wants to use a product that makes them throw up.
Actually, this is not entirely true: the rollercoaster is a commercially successful product that's fun and makes you puke at the same time, but it's the exception and not the rule. Just imagine your stomach turning upside down every time you look at your smartphone - you'd probably go back to your good old Nokia 3310 the next day.
If we want to see VR going mainstream, we have to address virtual reality sickness.
What is VR sickness?
Virtual reality sickness sounds like a new thing, but it's not. Motion sickness, a similar symptom, is as old as humanity. The earliest record comes from Hippocrates, who first described motion sickness caused by sea travel, and even the word nausea comes from "naus", the old Greek for "ship".
Similar symptoms have been observed in immersive environments (aviation training simulators) as early as the 1950s. Simulator sickness has been studied for decades now by doctors and the US Army. Without going into graphic details: it's really awful for some people.
Virtual reality sickness is something we just start seeing, but thanks to the research in simulator sickness we already have the tools and methods to make VR comfortable for the majority of the people.
Why VR makes people sick?
We don't know exactly, but it's very possibly related to sensory conflicts. When you start moving in real life, it's not just your brain processing the visual information. You also feel the movement in your body, most importantly in your vestibular system. You usually do a lot of muscle work, too. If you jump on a plane in VR, your brain receives very conflicting information: your eyes make you think you are flying, but you don't feel the speed in your gut.
Sensory conflict does not even have to be this strong to cause simulator sickness. The human brain is an incredibly fine piece of hardware, and even the slightest latency is noticeable. When you turn your head in real life the world is already there - consensual reality does not need to be rendered in real-time. Virtual reality is different, and if the drawing drops below a certain frame rate (more on this in a minute), you'll start noticing lags, glitches, and nausea.
Another cause of VR sickness is forced camera movement. You'd be pretty pissed off if someone suddenly grabbed and turned your head forcing you to look in a particular direction. This is not a problem on a flat screen, but it's a huge issue in an immersive environment.
Lastly, low-quality animation is known to be causing discomfort. This is an interesting point, as we know the brain is brilliant in filling perception gaps. Manipulating objects using hand tracking in virtual reality feels natural, even if your arms are very visibly missing. Our imagination fills the void, and if you think back to such an experience you probably won't even remember you had no arms.
The problem (called the "uncanny valley effect") starts when we see something that should look realistic, but it's not - especially poorly animated human characters. A low polygon body works well - your imagination kicks in. However, a high polygon body with poor, unnatural animation is disturbing. This is not related to motion sickness or simulator sickness, and it will not make you feel dizzy; just plain uncomfortable.
Virtual reality sickness is not an issue for about 80 percent of the people, but it makes the 20 percent mildly or terribly sick. Interestingly people under 20, women, and Asians are more susceptible to it.
Better hardware = less virtual reality sickness
Old televisions usually operate at 30 frames per second (fps). This is nowhere near enough for virtual reality use. VR needs at least 60 fps consistently, meaning frame rate should not drop under 60 even if it's a computing-heavy environment. Sony just announced that any game failing to maintain 60 fps will be refused to appear on the PlayStation VR platform. Games on the Oculus Rift and the HTC Vive should run at 90 fps - wonder you need a pretty powerful PC. The insert-your-phone head mounts are not this advanced, although the Gear VR (or, better, the phone) is technically capable of operating at 60 fps.
Another important factor is the type of the screen, IPS vs. OLED. IPS is usually associated with a more natural color balance, but it's relatively slow compared to OLED. This is one of the main reasons why Apple is not doing VR yet - they use IPS screens in all their models. OLED and its variants have been introduced by Samsung, and while most people love it, some dislike it very much. OLED is oversaturated, the color balance is way off, but it's bright and extremely fast. OLED is the way to go for VR applications - Oculus started with IPS, but switched to OLED.
There is one very interesting product coming out soon, designed to enhance immersion, but also to combat VR sickness. Samsung's Entrim headphones stimulate your inner ear to give you a sense of motion speed and direction. This solves a big part of the sensory conflict problem.
Better design = less virtual reality sickness
As a UX / world designer, you have little control over the technical features, and they are getting better by the day anyway; but you can, and you should combat VR sickness with good design.
1. Design a clean UI
As we talked about this in one of our earlier posts, you should not place any important control element to the periphery of the user's vision. Our vision gets blurry towards the edges, especially if you are using a less advanced platform like Cardboard. You should place the app menus to the center one-third of the field of view, so users do not have to tilt their heads too much.
Also, you should be very careful in using scrolling elements. Scrolling text is almost always a bad idea in VR. Consider using pagination instead, or try replacing the text with speech.
2. The user controls the camera (with very few exceptions)
Users must be able to look around just like they do in real life, every time, and the environment should follow. You can, and sometimes you should use "sticky" objects, like an emulated HUD (see the next point), but they are the exception, not the rule.
The camera always must follow the movement of the head as precisely as possible, with the exact speed. Parallax might look good on a website, but it will make people very sick in VR.
3. Use an anchor object if possible
Anchor objects, like an HUD or the frame of a vehicle, can reduce VR sickness as your brain has something fixed to focus on. Research shows even adding a virtual nose can help reducing dizziness by 13.5 percent. This won't have a negative effect on immersion - remember, your imagination is a very powerful ally.
4. Teleportation works in VR
You usually experience VR while sitting on a chair or walking around in a room (a fairly small one). When your body is still in real life but walking or running in the virtual world sensory conflict will eventually make you sick. You don't have to avoid moving around in VR - that would be very limiting - but as a designer you also should consider teleportation. The sudden change in the environment can be very confusing, so give the user audiovisual hints (fade out - fade in might work well) that something is going to happen.
5. Give the users time to orient themselves
Fast pacing action is great, but not if it makes the user puke. Every time you place the user in a new environment make sure you leave plenty of time to get familiar with the scene. Recognizable visual reference points (a tree, landscape, any unmovable object in the background) can help a lot.
6. Do not shake the camera
Explosions? Firing a rocket launcher? Falling from a cliff? In most games, you'll see the camera shaking. You might be tempted to think this adds to the immersion, but in virtual reality, it makes the player sick. Never shake the camera - it goes against rule #2.
7. Don't simulate walking
When you walk, and especially when you run, your head moves up and down a bit. Developers often simulate this on PC, especially in first person shooters, to give the user a more realistic feel of movement. On a flat screen, this looks good, but it is a big no-no in VR, as it instantly leads to virtual reality sickness.
8. Maintain a constant rate of speed
Sensory conflict is bad enough if you are sitting in a chair while your virtual avatar is running. It's even worse if you accelerate and decelerate, instead of maintaining a constant rate of speed. Choose the right speed depending on the vehicle (walking too fast, or flying too slow is confusing, too), and keep it constant.
9. Use zoom very carefully
You can zoom in and zoom out the camera in VR, but use it only when it serves a purpose, and when the user has control over it. Zoom is great in a sniper game triggered by pushing a button on the controller, but it is very confusing if it happens out of the blue.
10. Find innocent subjects for testing
Developers, especially those working with VR often, are the worst test subjects. They are less susceptible to virtual reality sickness. Think of a VR sickness test as something similar to a user experience research session. You can even create personas, then find the appropriate test subject - preferably across age, gender and race.