Nobody wants to
use a product that makes them throw up. Actually, this is not entirely true:
the roller-coaster 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. 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. 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 feel the movement in your body, most importantly in your
vestibular system. You usually do a lot of muscle work. 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.
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