First of all, what is cognitive load and where does it come from? Simply put, cognitive load is the amount of mental processing power needed to use your product. It's a term that is used a lot in UX design, and can be affected positively or negatively by every single design choice you make. Even the simplest decisions, such as the basic composition of content elements, or the color palette of your user interface, can help or hurt cognitive load.

The consequence of high cognitive load is fairly significant. Kathryn Whitenton said it best in her article "Minimize Cognitive Load to Maximize Usability":

“When the amount of information coming in exceeds our ability to handle it, our performance suffers. We may take longer to understand information, miss important details, or even get overwhelmed and abandon the task.”

Ignoring the impact that cognitive load can have on a VR experience means risking your users missing critical details or instructions, or even giving up on the experience entirely. Below are just a handful of VR experience design topics that you can use to critically examine whether what you’ve built is working for — or against — your users.

1. Introduce new objects or concepts one at a time

For those of us who are in VR regularly, it's easy to forget how overwhelmed you can get as a new user. Plop someone down into the middle of a VR experience full of virtual objects just screaming to be picked up and played with — you'll easily short-circuit their ability to focus on anything, especially the one thing you want them to be paying attention to. Populating the environment with one object at a time, removing clutter, and limiting the number of distractions will help your users focus on learning the new concept you're trying to show them.

Example: Fantastic Contraption introduces all the moving parts of their VR game one at a time and waits until the player performs each task before moving on to the next.

2. Rely on reality (to start)

Designing virtual environments that your users are already familiar with will cut down hugely on cognitive load — this is arguably the most impactful change you can make. When an environment is familiar to your users, they will be able to rely on their assumptions about what they can do there.

Similarly, virtual objects that look and behave like their real-life counterparts are also easier for users to predict and understand. A wrecking ball is heavy in real life, so swinging a virtual wrecking ball into the side of a building should cause some serious damage. If your intention is to deviate heavily from real life in the design of your environment and interface, look to industrial design or product design concepts that convey their uses through form and the way they behave when someone interacts with them.

Example: Job Simulator takes advantage of the design of familiar objects and uses realistic physics to make them behave in an expected way, while Cosmic Trip sets the bar high when it comes to conveying how to interact with unknown objects in an unfamiliar environment.

3. Put similar objects or actions close to each other

A term for this is "content chunking," which refers to the way we group similar pieces of information. Think about the way you organize your kitchen: if we have multiple items meant for a specific task (spices, cooking utensils), those objects tend to be stored, stacked, or placed next to each other. It's easier to remember where you can find the paprika if you know all of the spices are kept in the same place. Where and how to group things is one of the fundamentals of good UX design — a common real-life example is where to put the raisins in a grocery store so people can easily find them.

In every VR experience, there will be many different ways to group objects together: type, use, size, color, etc. Focusing on what each object is meant to be used for will help you decide where it should be located in order to reduce cognitive load. This is an iterative process, and it affects many different aspects of the user experience, so it is unusual to get it right on the first try.

Example: Itadakimasu, a therapeutic VR experience, puts hand gesture icons in the environment next to animal characters that respond to those gestures.

4. Map core actions to already-known or easy to learn input methods

The easier the input method, the easier it will be for your users to learn & recall how to perform the task that is associated with that input. Save your product's core tasks or mechanics for basic gestures, single-button inputs, or familiar input methods.

What constitutes a "known" input method will depend on your VR hardware. With NUI (natural user interface) devices in particular, such as the Leap Motion, users may be familiar with how hands work, but unfamiliar with how hands are tracked by the device. They may expect to be able to use hands in all the ways they are used to using them, even if your VR experience only supports a limited set of inputs.

Also keep in mind that "simple input" doesn't necessarily mean it will be easier for users to remember. The grip buttons on the HTC Vive controllers are notorious for tripping up new VR users, who may frequently forget that they exist or what they are used for.

Example: Tilt Brush made it easy to change brush size on the fly by mapping the brush size tool to the touch pad of the same controller that users paint with. (Presumably this means that brush size changing is a core action for artists in Tilt Brush, since it's being treated like one.)

5. Make permanent actions hard to fuck up

Being under a lot of cognitive load can make it easier to make mistakes. VR users can feel mentally pummeled with a myriad of new tasks to learn and environments to adapt to. Users under significant cognitive load are more prone to errors, which makes putting the "Delete" interactable next to the "Save" interactable dangerous.

If your VR experience has a way to delete, remove, destroy, or otherwise permanently affect something in a big way, you should make it harder for users to perform those actions. Permanent actions that take effort will go a long way toward preventing mistakes that are difficult to recover from, if recovery is even possible.

Example: Instead of selecting a button that says "Delete", Fantastic Contraption has players throw levels they don't want anymore into the mouth of a tiny volcano that’s located off to the side of the main menu interface.

6. Run your design through usability testing to make sure it’s working with users and not against them

A wise designer once said, "You are not your user." Users rely on a lifetime's worth of knowledge about systems, relationships, and communication, as well as their beliefs about how products work. This is their "mental model," the cognitive framework that each user refers to in order to determine what’s possible and what’s likely to happen while inside your VR experience.

Mental models can vary from person to person, sometimes wildly and sometimes in patterns. If you have ever had users tell you that a feature feels out of place, a part of the interface should be moved somewhere else, or that something fundamental seems to be missing from your product, this is a symptom of a mismatch in your design and their mental model. You can either change the design to better represent the user's mental model, or improve the user's mental model by making the interface more accurately reflect the systems underlying it.

Optional: Not sure what's wrong? Get help from an expert

If you are struggling with ways to improve the UX of your VR thing, you might want to hire a UX designer. I've been told it's difficult to find a UX designer who has experience with VR right now — if you're on the hunt, I can point you in the direction of some professionals I know.

If you need help, but can't hire a full-time designer, you might want to get a heuristic evaluation (fancy way of saying "expert review") of your VR thing from a UX professional.

Generally speaking, getting a UX person involved will probably cost money if it's more than just a simple question... but trust me, catching UX problems early will save you a lot of time, money, and grief later on.

Additional Resources

• This is your Brain on VR by Dr. Kimberly Voll
• Get started with VR: user experience design by Adrienne Hunter
• What is Virtual Reality? by Dr. Brenda Laurel
• 10 Usability Heuristics for User Interface Design by Jakob Nielsen
• Mental Models by Jakob Nielsen
• Computers as Theatre by Dr. Brenda Laurel
• UX Myths

Thanks for reading! If you want to hear more about UX design in virtual reality, see cool stuff my friends are making in VR/AR, or add a steady stream of unicorn emoji to your feed, you can follow me on Twitter @snickersnax 🦄

Img source: http://www.emdocs.net/cognitiveload/