Purdue: Virtual reality games often cause simulator
sickness – inducing vertigo and sometimes nausea - but new research
findings point to a potential strategy to ease the affliction. Various physiological systems govern the onset of
simulator sickness: a person's overall sense of touch and position, or
the somatosensory system; liquid-filled tubes in the ear called the
vestibular system; and the oculumotor system, or muscles that control
eye movements.
"Simulator sickness is very common," said David Whittinghill, an assistant professor in Purdue University's Department of Computer Graphics Technology.
"The problem is your perceptual system does not like it when the motion
of your body and your visual system are out of synch. So if you see
motion in your field of view you expect to be moving, and if you have
motion in your eyes without motion in your vestibular system you get
sick."
Anecdotal evidence has suggested simulator
sickness is less intense when games contain fixed visual reference
objects - such as a racecar's dashboard or an airplane's cockpit -
located within the user's field of view.
"But you can't have a cockpit in every VR simulation," Whittinghill said.
His research team was studying the problem when
undergraduate student Bradley Ziegler suggested inserting the image of a
virtual human nose in the center of the video display.
"It was a stroke of genius," said Whittinghill,
who teaches video game design. "You are constantly seeing your own nose.
You tune it out, but it's still there, perhaps giving you a frame of
reference to help ground you."
The researchers have discovered that the virtual
nose, or "nasum virtualis," reduces simulator sickness when inserted
into popular games.
Findings were presented earlier this month during
the Game Developers Conference in San Francisco. Also working on the
research are undergraduates James Moore and Tristan Case.
Forty-one test subjects operated a number of
virtual reality applications of varying motion intensity while wearing a
virtual reality headset. In one of the applications, the user navigates
the interior of a Tuscany villa. In another, it's the white-knuckle
thrill ride of a roller coaster.
Some of the subjects played games containing the
virtual nose, while others played standard versions. They were not told
that the nose was there.
"Surprisingly, subjects did not notice the nasum
virtualis while they were playing the games, and they were incredulous
when its presence was revealed to them later in debriefings,"
Whittinghill said.
Findings showed the virtual nose allowed people
using the Tuscany villa simulation to play an average of 94.2 seconds
longer without feeling sick, while those playing the roller coaster game
played an average of 2.2 seconds longer.
"The roller coaster demo is short, but it's very
intense at times, spinning upside down, jumping across chasms, plunging
fully vertical, so people can't do it very long under the best of
circumstances," Whittinghill said. "We had a reliable increase of 2
seconds, and it was a very clear trend. For the Tuscany demo it takes
more time, but eventually you start getting queasy, and 94 seconds is a
huge improvement."
Researchers also used electro dermal activity
(EDA) sensors to record electrical conduction across the skin, which is
affected by sweating due to excitement, a proxy indication of simulator
sickness. The measurements indicated EDA differences between subjects
playing games with the nose and without.
It isn't clear why the virtual nose evidently reduces simulator sickness.
"Our suspicion is that you have this stable
object that your body is accustomed to tuning out, but it's still there
and your sensory system knows it," he said.
The research is ongoing.
"Our long-term goal is to create a fully
predictive model of simulator sickness that will allow us to predict,
given a specific set of perceptual and individual inputs, what level of
simulator sickness one can expect," Whittinghill said.
Writer: Emil Venere, 765-494-4709, venere@purdue.edu
Source: David Whittinghill, 765-494-1353, dmwhittinghill@purdue.edu