Biomedical Engineering Reference
In-Depth Information
2.6 Simulator Sickness and Vection in VR
While a compelling sensation of self-motion in VR clearly increases the overall
believability and realism of a simulation, the occurrence and strength of vection can
sometimes also correlate with undesirable side-effects like motion after-effects or
motion/simulator sickness [
34
,
35
,
50
,
73
]. It remains unclear, however, whether and
how vection might be causally related to simulator sickness, as vection is more easily
observed when visuo-vestibular cue conflicts are small, whereas motion sickness
tends to increase for larger cue conflicts [
50
,
73
]. Moreover, visually-induced motion
sickness can occur without either vection or optokinetic nystagmus [
46
], indicating
that vection cannot be a necessary pre-requisite of visually-induced motion sickness.
Carefully planned research is needed to investigate and disambiguate underlying
factors promoting desirable outcomes (like compelling self-motion perception with
reduced simulation cost) versus undesirable side-effects (like simulator sickness,
after-effects, or (re)adaptation effects) and their potential interactions. As displays
become more effective in inducing vection, they might also become more powerful in
inducing undesirable side-effects. Thus, applications should be carefully evaluated
in terms of not only intended benefits but also potential undesirable side-effects
(see also conceptual framework in Sect.
2.9
).
2.7 Perceptual Versus Cognitive Contributions to Vection
While self-motion illusions have traditionally been explained by perceptual (lower-
level) factors and bottom-up processes (e.g., stimulus frequency, velocity, or field
of view), recent studies provide converging evidence that self-motion illusions can
also be affected by cognitive (higher-level) factors and top-down processes. In the
following, we will briefly review and discuss relevant findings before attempting to
integrate them into a conceptual framework in the final sections of this chapter.
2.7.1 Lower-Level and Bottom-Up Contributions to Vection
Visually-induced self-motion illusions have clearly received the most attention in
vection research so far, and a number of lower-level/perceptual factors and bottom-
up processes have been shown to facilitate visually-induced vection, which will be
briefly discussed below. More in-depth discussion of lower-level factors and bottom-
up contributions for vection can be found in [
2
,
23
,
38
,
39
,
61
,
86
,
123
].
Visual field of view.
Although vection can sometimes be induced using field of views
as small as 7
5
◦
[
3
], increasing the field of view subtended by the moving stimu-
lus generally enhances all aspects of vection [
10
,
16
,
23
,
32
]. Strongest vection is
observed with full-field stimulation, up to a point where illusory self-motion cannot
.
