VR is the development of artificial environments
that can be navigated directly.They can be the relatively simple or very complex.They fall into two general categories: window on the world
and immersion.In
window on the world, the user views the environment as from a
window into the world.The monitor screen is the window and the information on
the screen provides the visual information about this world.This is the type of VR involved in most video games and a very primitive version of
this type of VR is illustrated in Figure 21.The more compelling and interesting type of VR occurs
when the person is immersed in the environment.This type of VR uses helmet-mounted displays to generate
the visual information, often has an integrated sound system,
and occasionally provides tactile feedback.It is this latter type of VR that holds the most interest,
but research and study is proceeding on both types of VR.
Figure 21. Here
is a very primitive virtual environment of the window on the
world type. Use the arrows to navigate to the right and
the left and observe the movement of the two objects in the display. [Figure 21 description]
One of the research advantages of the most advanced VR systems
is that it can provide controlled inputs to the visual, auditory
and tactile systems.To date, the vast majority of studies in sensation
and perception have primarily investigated the senses separately.However, many experiences are based upon inputs
from multiple sensory systems.For example, hearing and seeing a bat hit a ball.Consider how jarring it is to sit so far away that the
sound and the sight are not integrated.
The study of body orientation, for example, focuses on a fundamentally
integrated sensory system.A series of recent studies suggest that visual information
alone may be sufficient for determining whole-body translation
and linear movement in the virtual environment.However, feedback from the tactile systems may be needed
for accurate determination of rotation (Chance
& Loomis, 1987; Richardson,
Hegarty, & Montello, 1997).
Richardson et al. (1997)
found that going around a staircase in a virtual building leads
to larger errors in determining their location relative to their
starting point than either learning the environment from maps
or actually moving through the real version of the environment.Chance and Loomis (1987)
studied perception of direction in individuals moving in virtual
environments, with or without tactile feedback.Chance and Loomis found that if a person actually
rotates but translates via the virtual environment, thus receiving
the tactile input from the rotation, they kept their sense of
direction far better.We
know that visual input is suppressed during saccadic eye movements,
which accompany body rotations.Perhaps the orienting system, not expecting good visual
input during physical rotation, has developed a tendency to rely
more on tactile input (Krantz
& White, 1989; Volkmann,
1986) . The need to
rely on tactile input may result from the fact that during the
illusion of rotation in a VR environment, the vestibular system
is not activated, an illustration of the importance of understanding
the integration of different sensory systems (Cohn,
Dizio, & Lackner, 2000). The VR environment
is especially suited to studying multi-sensory and sensory-motor
integration.
Sensory research is also proving to be helpful to engineers working
on VR systems.In
a recent paper, Cutting (1997)
gives a review of the visual information needed for VR applications,
including how space perception and the use of depth cues can
assist VR engineers in developing appropriate visual inputs.An important feature of Cuttingís work is his quantitative
approach to VR.Just
as it was necessary to develop equations for color matching to
be used in monitors and printing, so it will be necessary to
provide quantitative functions for other visual functions before
they can be applied to VR.Thus, research in sensation and perception may well take
the form of taking well-understood phenomena and developing quantitative
models for application. This research may also indicate
new visual functions that need to be explored. One possible
issue is the location of the center of projection relative to
the persons eye height. Dixon, Wraga, Proffitt, & Williams
(2000)
found that the relationship between a subjects eye height and
the center of projection profoundly affected the perception of
size.
Another interesting question related to VR that is both a research
question and an application issue is the difference between the
two forms of VR.The experience of VR in the immersion techniques
is far more immediate than the window on the world.What are the features that makes this so?One difference is that the field of view tends
to be far more restricted in the window on the world (Dichgans
& Brandt, 1978) though Dixon et al. (2000)
found that an immersion technique with a restricted field of
view had as strong a relationship between eye height and perceived
size as did a full immersion technique. The window on the
world condition in the same paper showed now effect of the relationship
between eye height and center of projects. These results
suggest that the difference between the two forms of VR is more
than just a difference between the size of the field of view.All in all, VR is a fruitful field for psychological research
into sensation and perception and vice versa.In fact it appears that the development of VR and the
use of VR as a research tool in sensation and perception may
be tightly intertwined.