what is virtual reality headset
A head mounted display developed in 1985 by Jim Humphries and Mike McGreevy at NASA’s Ames Research Center – photo credit

This sounds like a simple question, but it is one that I’ve been meaning to discuss. Without a foundation, everything we talk about on this site is more or less floating somewhere in abstract space. To ground the subject, and to truly understand it, we must ask and define: what is virtual reality?

While the contemporary answer to the question, “what is virtual reality”, usually involves head mounted displays and computers, I think a more objective definition of virtual reality is necessary. When it comes down to it, virtual reality is no individual piece of technology; often it is produced with a synthesis of many technologies, but at a fundamental level virtual reality is nothing more than tricking the senses. You can literally build your (virtual) reality from scratch once you can trick the senses convincingly.

Yes, this definition is broad and will need some additional terminology to specify the many different types of virtual reality that are out there, but I think this definition is necessary. After all, while it might be possible to achieve VR with certain technology, there is no single, definitive component.

Take for instance a binaural recording recording. If you listen with headphones on and close your eyes, the sound is such that people are right there in the room with you. Your better judgement tells you that there is no one in the room moving around you, but thanks to the cues provided to your brain you can precisely locate these virtual people in the room around you — no head mounted display necessary.

Conversely, we can achieve VR even without  any audio. People who have used HMDs say that when standing on the edge of a cliff and looking down, they get the same sensation as if they were doing it in real life (the effect is enhanced with proper head tracking and a wide field of view). They know that they aren’t standing on the edge of a cliff, the but brain’s visual channel has been fooled into perceiving this virtual feeling of height, and the rest of their body responds as though it is real — including holding their arms out to their sides for balance.

We should not restrict the definition of virtual reality to certain technology because VR is entirely independent of any equipment. The only thing you need to experience virtual reality is a brain. In fact, the brain is capable of providing the world’s most immersive virtual reality experience (for now, anyway). Many nights I’ve had lucid dreams which included much flying and a vivid ‘free fall’ feeling in my stomach. It’s the same feeling I get when I’m on a rollercoaster. And let me tell you, flying to the top of skyscrapers and then jumping off of them (in my dreams) can’t be matched by any current VR technology.

The brain is really the ultimate key to VR. It is how we know the world.  We can create things that we think are real that do not actually exist, so long as we can find ways to sufficiently deceive our senses — and the act of doing so is what we call virtual reality.

Addendum: A useful approach to talking about the ‘immersiveness’ of a VR system would be based on which senses are being tricked and how many. Obviously a single-sense VR system (ie: sight) wouldn’t be as immersive as a two-sense VR system (ie: sight and sound), and both would be inferior comparison to a three-sense system (ie: sight, sound, and touch) — and so on. This isn’t a definitive method of ranking immersion — as one HMD might be better than another at tricking our sight than another — but it is a very easy way to at least get a rough comparison of the immersion of two difference systems. For example, if we use the five normally recognized human senses (sight, sound, touch, taste, and smell), Project Holodeck would be considered a 4-sense VR system as it actively works to trick all senses but taste. On the other hand, a setup that only uses an HMD would be a 1-sense VR system.

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Ben Lang
Ben is the world's most senior professional analyst solely dedicated to the XR industry, having founded Road to VR in 2011—a year before the Oculus Kickstarter sparked a resurgence that led to the modern XR landscape. He has authored more than 3,000 articles chronicling the evolution of the XR industry over more than a decade. With that unique perspective, Ben has been consistently recognized as one of the most influential voices in XR, giving keynotes and joining panel and podcast discussions at key industry events. He is a self-described "journalist and analyst, not evangelist."

  • Hmh! This would be an interesting way to rate virtual reality experiences. A grade for each sense that can be fooled/simulated. Though for what? For individual games/movies or for hardware setups?

    Another thing I bumped into on the MTBS3D forum in the discussion of VR experiences was that a passive experience is not VR, it has to be interactive or else it’s just like watching TV and not really immersive as you are, again, passive and cannot affect the world.

    I’m not sure I agree there, and as you bring up the virtual barber it seems like a passive experiences can be classified as virtual reality too. As long as you feel like you are somewhere else, pretty much, it should be possible to call it virtual reality… no?

    In a sense, just watching a screen with a movie playing on it is virtual reality, just with a fairly low rating as the immersion is broken quite easily. I remember watching Blair Witch Project in a perfectly black room though, and it pulled us in like crazy! Scary for sure! Watching the Matrix premiere in theaters was also crazy immersive, sheesh, a long time go. “Is this really reality?”

    Would a system where you control cameras in another place with your HMD be virtual reality, or “just” reality by proxy? Is there a difference? It would be experiencing the real world, but, again, by proxy. And would the fact it was a live feed make it any different from watching a spherical recording at a later time?

    And surely my brain is going rampant, but. Wouldn’t surfing the web be one sort of virtual reality? It’s the reality, but in a different form, but what we do are real actions that cause real reactions, right? Or is the web part of the actual world, reality?

    Would surfing the web, posting and reading, be similar to playing a game? In a game the game world is the virtual reality, but on the web sites and content themselves makes up the reality. Does a virtual reality have to consist of tangible physical objects placed in a 3D space?

    Then looping back to the article. If we define virtual reality only by the senses fooled, not the world or presentation of the world… I guess even a book is virtual reality? It makes you (to different degrees) experience an imaginary world inside your head. fooling the brain, and if it’s really late at night it can be really immersive. Or is that hallucinatory?

    I remember reading a sci-fi book with a torture scene way past midnight back when I was a teenager, and I was so much into the story I was about to faint by the horrorific experience of the protagonist, but then again I was a teenager and full of hormones too :P

    So many thoughts. I can see how, as you say, what would appear to be a simple question can turn into a large mess of questions, hahaha. Enjoy!

    • Ben Lang

      Great points, Andreas. My definition definitely extends VR to any experience which can trick your senses which could indeed included books, movies, and other forms of media. Like I said, we need to look at when the senses are tricked — a scary movie where something pops out at you and makes you jump has definitely just given you a virtual reality experience, albeit briefly. The threat wasn’t real, but your body perceived it to be so and reacted to it as though it would a real threat. The experience of VR in this case may have only been for a moment, but it was definitely there.

      As for your example with a book… I think a better description of what you experienced was empathy for the character rather than having your senses be fooled. Indeed you may have felt sad, but unless the book made your body clench up in pain like you were about to be prodded with a hot poking iron, then I’d say it wasn’t a VR experience.

      I don’t agree with VR needing to be interactive to qualify as VR. After all, an immersive movie might have you feel like you are sitting in the back seat of the car with the characters, but you are just watching which would be considered interactive — still you are convinced based on sight and audio that you are in the car with those characters.

      The reality by proxy idea is a puzzler lol.

      I wouldn’t call surfing the web virtual reality… what senses are being tricked?

  • Hi Ben,
    my simple version of “what is vr?” is simple: “presence in a virtual world”.
    The notion of “Presence” here is fundamental.
    Then you have to define presence :)
    It has multiple definitions, but the simplest one is the feeling of “being there”, forgetting about the real world and that your senses are tricked by some devices.
    You can read a more complete discussion here: http://cb.nowan.net/blog/a-definition-of-vr/
    Cheers,
    cb

    • Ben Lang

      Hi Cb, thanks for your link, definitely some interesting ideas there (I’ve subscribed to the site)

      I wonder if perceived “presence in a virtual world” is too easy to misconstrue though. If you listen to the barber shop example linked above, I would contend that we are talking about virtual characters in MY world, rather than me being present in a virtual world (of course that won’t always be the case). This is why I think the sense-tricking definition is useful.

      • Great points, Andreas. My definition definitely extends VR to any experience which can trick your senses which could indeed included books, movies, and other forms of media.

        What sense is a book fooling ?

        I don’t agree with VR needing to be interactive to qualify as VR. After all, an immersive movie might have you feel like you are sitting in the back seat of the car with the characters, but you are just watching which would be considered interactive — still you are convinced based on sight and audio that you are in the car with those characters.

        Then we’re not talking about the same kind of VR :)
        Interaction and Immersion and are the two basis of Immersive VR.

        From the article on my blog:

        In “Le traité de la Réalité Virtuelle” : ” Having a cognitive activity in a virtual environment without a physical activity (sensori-motor) is outside the boundaries of VR”.

        As explained furthermore by Mel Slater : ”In the case of a desktop system the situation is quite different, the feeling reported as ‘being there’ if it comes at all is after much greater exposure, requires deliberate attention, and is not automatic – it is not simply a function of how the perceptual system normally works, but is something that essentially needs to be learned (…) PI may still be reported, but this is as a consequence of additional creative mental processing.”

  • Andrew

    Or, you can use the Remee sleeping mask product where you can dream lucidly with vivid senses.

    • Ben Lang

      Indeed, I’ve got a friend with one of these. There are also free strategies you can use to try to increase the occurrence of lucid dreams.

      • Haha I so totally thought that was a spam comment, then realized it offered an alternative to computer generated VR, ehrm.

        If you are after hallucinations I have read about a method without using drugs. Use sealed headphones and listen to radio noise while having half a ping pong ball over each eye in a bright room. According to what I read, ages ago, the brain will have no sensible input and thus start to make up whatever, like dreaming, but while you are awake. I have not tried this myself so I’m not sure if it works, or how sane it will leave you afterwards.

        Another thing I read was what happened if you stayed up for very long, meaning 50-100 h, that will also induce hallucinations. Question is which is the least risk to your health, mental or physical.