Biomedical Engineering Reference
In-Depth Information
moving when running on a treadmill, nor do their inertial systems experience any net
acceleration” (p. 415). Informal observation, discussions with colleagues, and pilot
studies by the authors corroborate the notion that biomechanical cues from walking
on linear treadmills hardly ever lead to compelling and reliable sensations of self-
motion that matches the walker's biomechanical motion, even for the most advanced
linear treadmills that include force-feedback harnesses.
This might, of course, be related to the lack of any net acceleration cues as Durgin
et al. pointed out [
26
]. Most treadmills simply do not seem to be long enough to
allow for sufficient motion cueing and physical translations that would allow for
sustained biomechanically-induced linear vection that would approach the intensity
and compellingness of self-motion illusions induced by moving visual stimuli (for
recent reviews in the context of VR, see [
34
,
86
,
100
].
Hence, for the current chapter we will pursue an alternate approach, by focusing
not on how to enable realistic walking in VR (which is covered in depth by other
chapters in this topic), but on how to provide a compelling and embodied sensation of
self-motion through computer-mediated environments with minimal or no physical
motion of the observer, with or without walking. In particular, we will review and
discuss how we can utilize and maximize illusory self-motions (“vection”) that can
be induced by visual, auditory, and sometimes biomechanical/somatosensory cues,
and how these different cues contribute and interact, often in a synergistic manner.
Especially for visually-induced vection, there is a large body of literature that will
provide essential guidelines, and dates back to more than a century ago [
33
,
60
].
Here, we will start with a brief review on visually-induced self-motion illusions, as
they have received by far the most attention in research and are known to induce
quite compelling vection (Sect.
2.2
). After this general introduction to vection, we
will review potential relations between walking and perceived self-motion and self-
motion illusions (Sect.
2.3
). In particular, we will discuss how walking interacts with
other sensory information such as visual or auditory motion cues (see Sect.
2.4
) and
briefly cover further cross-modal effects (Sect.
2.5
) and potential relations between
vection and simulator sickness in VR (Sect.
2.6
). We will discuss both perceptual
factors and cognitive contributions (such as participants' perception/knowledge of
whether or not actual self-motion might be possible), and how to best utilize such fac-
tors and interactions in VR to provide a compelling and embodied sensation of self-
motion through computer-simulated environments while trying to minimize overall
costs and efforts (Sect.
2.7
). We will continue by discussing how self-motion illusions
might facilitate spatial orientation in VR (Sect.
2.8
), and conclude by proposing a
conceptual framework that integrates perceptual and cognitive factors and is centered
on perceptual as well as behavioral effectiveness of VR simulations (Sects.
2.9
-
2.10
).
2.2 Visually Induced Self-Motion Illusions
In this section, we will provide a brief review of the literature on self-motion illusions
that is relevant for the current context. More comprehensive reviews on visually
