From: LHETTINGER@FALCON.AAMRL.WPAFB.AF.MIL
Subject: Motion Sickness and VR
Date: Fri, 18 Jan 91 10:39 EDT



        Among the many benefits to be derived from developments in
virtual reality there is at least one potential negative side
effect that needs to be addressed - the problem of motion sickness.
For the last several years a number of us, working primarily under
the sponsorship of the Army and Navy, have been investigating the
phenomenon of motion sickness in flight simulators.  We have been
particularly interested in trying to determine the causes of
sickness in situations where the is no physical motion of the user,
i.e., where all the motion is visually specified.

        We have recently published data indicating that only those
people who experience strong illusory sensations of self motion
(traditionally refered to as "vection" in the psychophysical
literature) will experience problems with sickness.  The vection
illusion consists of the overwhelming sensation that one is moving
despite explicit knowledge to the contrary.  The quality of the
illusion of motion that is imparted to the user is often taken as
an informal "measure" of the quality of a simulator and,
presumably, other types of virtual imaging devices whose design
intentions are similar.

        Our concern centers primarily around two issues:  (1) the
quality of training afforded by simulators that make a significant
number of people sick, and (2) safety concerns for users hours
after leaving the virtual environment.  While data on the long-term
effects of "simulator sickness" is scarce, there are numerous
anecdotal accounts of these problems.  One of the more dramatic
concerns an Air Force pilot who, upon driving home after an
extended training session in a flight simulator, experienced a 180-
degree inversion of the visual field.  Fortunately, he was able to
safely stop the car and recovered soon afterward.

        Questions of user well-being, to say nothing of potential
liability consideration, make this a rather critical issue for the
development of virtual reality.  I am anxious to communicate, share
literature, debate issues, examine solutions, etc. with any and all
interested individuals.

Larry Hettinger
Logicon Technical Services Inc.                         (513) 255-8770
P.O. Box 317258
Dayton, Ohio  45431-7258

lhettinger@falcon.aamrl.wpafb.af.mil