Monday Musings: Motion Sickness

Welcome to Monday Musings! These are are shorter-form, note-like blog posts that I share that may or may not be related to VR/AR, but that I want to share some quick thoughts on, get some extra insight on, or share out quickly.

Hey everyone!

One of the most dreaded aspects of immersive computing is motion sickness – that pesky phenomenon where your brain thinks you’ve been poisoned and tries to make you throw up. In today’s Monday Musing, I’m going to spend some time doing a brain dump of my experience with motion sickness and talk a little bit about some interesting things I’ve found related to that annoying faux-poisoning response.

A common motion sickness trigger in the physical world is reading or using devices while in a moving vehicle

What is motion sickness?

To start off, I’ll begin with a brief description of what motion sickness is (disclaimer: I’m not a doctor, don’t take what I say as medical advice, etc. etc.) and why VR can cause it to happen. Motion sickness, put simply, is caused when your vestibular system (specifically, your inner ear) notices that some of your sensory input is contradictory. When this balance is thrown off, your brain assumes that something has happened to make you sick (specifically, that you’ve been poisoned) and tries to get your body to throw up the “poison”. If you’ve experienced motion sickness before, you’ll notice that it takes quite a long time for motion sickness to subside, depending on the intensity of it, but if you throw up, it tends to fade away fairly quickly.

Motion sickness in the physical world tends to be caused when your eyes and body send conflicting signals to the brain – carsickness, as an example, is caused when physical motion doesn’t align with what you’re seeing visually out the window – and can be triggered by many different things where you’re moving and see a static environment, or vice versa. Although motion sickness is generally a conflict visually and physically, I’ve also gotten it from incorrectly placed 3D audio.

Motion Sickness in VR

With virtual reality, performance and high frame rates are important for preventing motion sickness, but many individuals are more prone to it than others, and the types of experiences make a big difference in terms of triggering nausea. In VR, the idea of forced locomotion (moving a player without their input) or a very fast-moving scene (either active, as in an FPS game, or passive, as in a roller coaster demo) are both common triggers of motion sickness, since these effects tend to exacerbate the conflict of being stationary in a chair while seeing visual motion. Highly performant experiences tend to reduce other visual conflict cues, such as flickering or a perceived reality break, but due to the sensitivity in some individuals, it doesn’t tend to completely eliminate the risk of motion sickness.

In addition to frame rate performance, there are other components of virtual reality applications that effect the likelihood of causing motion sickness – and it’s not really well understood what all of those are or how they vary from person to person. I talked briefly about two techniques (shape from shading vs. motion parallax) that our brains use for resolving 3D objects at Grace Hopper this year – check out the abstract if you want to know more – but there’s a lot to still be done to figure out more about adapting for this at scale as immersive computing becomes more commonplace.

Various studies show that women are about 3 times more likely to experience motion sickness than men.

Weird Things I’ve Noticed About Motion Sickness since joining the VR Industry

Motion sickness is just weird, period. It’s generally self-reported, and it can be hard to figure out patterns and triggers since it varies so widely between different individuals. In the spirit of getting more information out about it, though, I wanted to capture a few things in this post that I’ve personally (n=1) experienced with motion sickness.

I am much more prone to physical-world motion sickness now

Before I started using VR devices regularly, I hardly ever got motion sick. If I really pushed what my vestibular and proprioceptive systems were capable of, and worked on a laptop while in the back seat of a car driving through the mountains (guilty!) then I’d experience carsickness, but for the most part, I’ve always considered myself less prone to motion sickness than average. The first time I seriously sat down and played a game on my Oculus Rift (Radial-G on a MacBook Pro, breaking all the rules here) I got horrible motion sickness, but that was all on me. Since then, the more time I spend in VR, the less likely it is I’ll get sick, but I find myself getting motion sick on airplanes for the first time in my life. It’s almost as though my brain is adapting to the triggers in VR at the expense of being able to handle variations in the physical world. Fascinating!

Our natural instincts can be wrong

The last time I started to feel motion sick on a turbulent plane ride, I found that my natural inclination was to grab onto the seat arms and hold myself as steady as possible to counter the motion of the plane. That said, knowing what I do about the proprioceptive system, I also realized that this was probably the worst possible thing to do to help with the nausea – so I started gently swaying with the turbulence. Sure enough, the motion sickness started to subside instantly. I also tend to now move my body a little more when I’m in a VR experience, and even just the slight motion tends to be enough to shorten the delta with vestibular conflicts.

So What Can We Do?

I think I mention this every post – but there is a lot of innovation occurring in the VR and AR industry right now, and attacking the challenge of motion sickness is one great place that designers, researchers, developers, and engineers can come together and look past the frame rates and at other factors that influence vulnerability to what is arguably the most uncomfortable part of virtual reality. If you’re an avid user – document your experiences and give feedback to developers about their experiences. Developers – let’s innovate on how we’re rendering shadows and lighting effects and try to minimize other types of visual inconsistencies! I know it’s not an easy task, but we’ve gotta start somewhere! Consider partnering with user experience researchers, branching outside of the tech industry, and make sure you’re testing in a wider user pool.

Let’s make simulation sickness a note in the history books with this wave of VR experiences!

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