Biomedical Engineering Reference
In-Depth Information
Indeed, when averaged over trial repetitions, participants did not report any substan-
tial net self-motion. This might have contributed to the above-mentioned decline in
spatial updating performance when participant did not physically move [
29
].
It is, however, conceivable that a compelling illusion of self-motion (even with-
out any actual physical motion) might be sufficient to enable spatial updating per-
formance similar to physical motions, or at least better than in purely imagined
perspective switches. Riecke et al. [
90
] tested this hypothesis and provide first
evidence that self-motion illusions might indeed help us to update target locations
in the absence of physical self-motions. After learning the layout of nine irregularly
arranged objects in the lab, participants were blindfolded and asked to point to those
previously-learned objects from novel imagined perspectives (e.g., “imagine facing
'mic', point to 'hat' ”). As predicted by prior research [
80
,
97
], imagined perspec-
tive switches were difficult when participants remained stationary and simply had to
imagine the perspective switch. Both pointing accuracy and consistency (“configura-
tion error”) improved, however, when participants had the illusion of rotating to the
to-be-imagined perspective, despite not physically moving. Circular vection in this
study was induced by combining auditory vection (induced via rotating sound fields)
with biomechanical vection (induced by stepping on a circular treadmill, similar to
sitting stationary above a turning carousel) in order to avoid visual cues that might
interfere with imagined perspective-taking.
While further studies are needed to corroborate these findings, these data suggest
that providing the mere illusion of self-motion might provide similar benefits in
terms of spatial orientation and perspective switches as actual self-motion. This could
ultimately enable us to design effective yet affordable VR simulations, as the need
for physical motion of the observer could be largely reduced, which, in turn, reduces
overall costs, space and equipment needs, and required safety and simulation effort.
2.9 Conclusions and Conceptual Framework
In conclusion, the above review of the literature supports the notion that cognitive
or top-down mechanisms like spatial presence, the cognitive-perceptual framework
of movability, as well as the interpretation of a stimulus as stable and/or belonging
to the perceptual background, do all affect self-motion illusions, a phenomenon that
was traditionally believed to be mainly bottom-up driven ([
85
], for reviews, see [
86
],
[
100
]). This adds to the small but growing body of literature that suggests cognitive
relations between the amount of presence/immersion/involvement and self-motion
perception [
91
,
92
] suggests that these factors might mutually affect or support each
other. While still speculative, this would be important not only for our theoretical
understanding of self-motion perception, presence, and other higher-level phenom-
ena, but also from an applied perspective of affordable yet effective self-motion
simulation. In the following, we would like to broaden our perspective by trying to
embed these ideas and findings into a more comprehensive tentative framework. This
