Causes of discomfort in VR, and how creators resolved them — Part 2

I’ve been learning about XR during this Pandemic for a while now. This article series will be the first of many where I aggregate all my learnings of XR design best practices with real-world examples and my personal experiences.

I’ve talked in-depth about the 1st category of causes: what you see does not live up to what you feel. If you missed it, here’s the link:

Causes of discomfort in VR, and how creators resolved them — Part 1

For this 2nd part, I’ll walk you through this other category:

What you feel does not live up to what you see

In this case, visuals are pretty realistic, almost too realistic that your brain is confused with signals sending from your body that lives in the real world.

For the majority of the time, we’re talking about this 1 root cause: Movement: The conflict between your eye convincing you that you’re moving (Vection) and your body (vestibular sense) telling you you’re not.

And due to hardware limitations, instead of influencing the body to bring that parity to the virtual world, creators often times will adapt the content and interaction of the virtual experience to mitigate the conflict.

Here I listed the most common strategies creators use to do that:

1. Only allow users to move, by moving their own bodies.

With 6 Dof headsets, users have the ability to move/walk freely within the virtual world at their own pace. If you can intentionally design the virtual space and experience that allows them to do just that, there will be no conflict and discomfort at all!

If you need much more space than users' physical area, some techniques can help trick people to walk in circles while thinking they’re walking straight, breaking away from their physical space limitation.

VR team presents infinite walking in virtual environments (w/ video)

Unseen Diplomacy on Steam

2. If #1 doesn’t work, make sure movements are at least user-initiated.

This gets into the realm of different VR locomotion techniques:

• Teleportation:

This is the most common locomotion technique and it works pretty well. Similar to movie cuts, by mimicking the eye blinks and the sense of instant “teleportation“, users will be brought into the new position by “magic” while standing still so the brain won’t be looking for the sense of accelerating/decelerating from the body.

Microsoft has a very specific breakdown of the teleportation steps:

Comfort - Mixed Reality

• HMD tilt acceleration

The movement to one particular direction will be initiated by users tilting(roll or pitch) their head towards that direction.

Based on research, my theory is that this technique is actually trying to trick your vestibular sense to think that you accelerated for a short amount of time when tilting:

Sensing linear acceleration

• Jogging in place

Instead of running forward, this locomotion method has the users jogging in place to mimic the running experience.

One theory for how it reduces discomfort is that our vestibular sensors are pretty sensitive and it can’t accurately keep track of position when they’re in a lot of movement. That’s how creators could bypass those sensors and make the user’s body believe it’s actually running forward.

PocketStrafe

• Grab and pull

Instead of moving within the virtual space, this technique allows users to grab the space/scene and pull over to get closer to things. The most common usage for this one is in climbing scenes:

The Climb on Oculus Rift

Google blocks utilize a similar technique allowing users to navigate within the virtual space they created themselves.

Blocks - Create 3D models in VR - Google VR

• Propulsion

This technique sets up the virtual space as a zero-gravity environment and simulates the propulsion system from spacesuit for movement. Echo VR does just that:

Echo VR: Battle Robots In Zero Gravity With Quest | Oculus

• Tunnel vision:

The peripheral vision is most sensitive to movement. By providing a tunnel vision, it essentially blocks users’ peripheral vision from seeing things move by thus reducing the sense of movement and discomfort. This could be used when moving between completely different environments. It could also be combined with traditional directional movement controls to minimize discomfort.

In Mini motor racing X, it uses tunnel vision for dramatic movements.

In Google Earth VR, peripheral content is cleared with very basic structures to minimize discomfort.

3. If making movements non-user-initiated is unavoidable, creators will try the following things:

• Making the movement along a straight line at a constant speed

Similar to teleportation, this setting allows users to feel still while in a movement. Oculus calls it artificial movement.

You can see in this scene the player is standing on a straight-moving platform that takes them into another scene

• Minimize unnatural movement

As human beings in our daily lives, we rarely move from side to side or backward. Making users do that in VR is likely to cause discomfort. You can see in the MINI racing X example I showed earlier, the tunnel vision only shows up when the vehicle is doing side to side movement. This is also why I personally experience discomfort in this really beautifully made immersive VR story when moving sideways.

One of the scenes in The Neon Jungle where the audience is moving sideways with the initial viewing direction.

• Minimize vertical movement

Human beings are pretty sensitive to gravity so any change of speed on the z-axis will likely cause discomfort.

• Be mindful of a dramatic change in speed

A good example would be collisions! This is the time your brain is expecting loud and clear deceleration signals. The following GIF was the first time I experienced severe discomfort when I was driving in Project Cars 2 and bumped straight into the tire wall.

Driving and colliding in Project Cars 2

• Be mindful of speed

Compared to the one above, this one is quite interesting as it’s referring to the constant speed rather than acceleration/deceleration. It’s one of the guidelines on the Oculus developer site:

Speed and discomfort in VR do not demonstrate a straightforward relationship to one another. Slow speeds (i.e. slow-motion) have been reported as less discomforting than a normal pace of human locomotion. Unnaturally rapid velocity has also been shown to be less discomforting than a normal human pace. As a reference, human locomotion generally falls between 1.4 m/s (walking) and 3 m/s (light jog).

4. Design a progression that allows people to get used to it.

Most users will adapt and slowly getting used to the troubling movement, making them less susceptible to discomfort. That’s why all major platform guidelines are recommending user test the games/apps with real participants rather than designers/developers of their own.
Creators have been utilizing this as well, creating flexible options, dynamic onboarding experiences, or a progression system that will increase the intensity of movement as users getting used to it.

Mini Racing X lets you choose the bird’s-eye view to control the vehicle to eliminate discomfort.

Echo VR uses a lengthy but patient, progressive, and necessary onboarding to have users adapt to their 0-gravity virtual world with the propulsion system.

5. Creative accessories that enhance the virtual experience.

This is for sure the most ideal solution for the user. Bringing their body as closer to the virtual reality as possible, utilizing gravity, sound, touch, haptic, vibration, and so on:

DropLabs’ EP-01 speaker shoes make for an excellent VR accessory

So that’s it. 2 major categories of causes of discomfort, with real-world examples of how creators resolved them.

If you want to see even more locomotion techniques and examples, head over to Locomotion Vault: https://locomotionvault.github.io/. You won’t be disappointed!

Thanks for sticking with me this far. Feel free to DM me or leave me a comment here about what you think of this format and if you find it helpful. ;)