Biomedical Engineering Reference
In-Depth Information
1.5 Conclusion
In this chapter, we have enumerated and briefly described the contributions of three
external (visual, auditory, and somatosensory), two internal (vestibular and kines-
thetic), and two efferent (efference copy, and attention allocation) sources of infor-
mation that collectively and routinely inform humans about their place in the envi-
ronment. With few exceptions, each of these information sources in isolation can be
sufficient for acquiring at least rudimentary knowledge of the environment and one's
movement through it. At the same time, because of our flexibility in handling var-
ious combinations of spatial information, none appears to be truly necessary, even
for generating relatively abstract and sophisticated knowledge about one's envi-
ronment. Thus it is a complex endeavor for researchers to determine the relative
contributions of different sources of sensory information when—as is typical in real
world situations—most or all are differentially available. Nonetheless, a great deal of
exciting contemporary research has begun to describe and understand how different
sources of information are acquired, weighted, and combined in the creation and
expression of our environmental knowledge.
These issues have very real consequences for users of virtual environments. Cur-
rently all VE systems must make some sacrifices on the information that they provide
to users. Desktop systems andCAVES eliminate or degrademany body-based sources
of spatial information, while HMD systems limit the quality of visual information and
(typically) the range of full-body movement. Research on the relative importance of
these different sources of sensory information is critical for making intelligent deci-
sions about how to use and choose among the many different options for VE systems.
The issue of conflicting or degraded sensory information in VEs has additional prac-
tical importance when one notes that discrepancies among sensory information are
widely believed to underlie the onset of simulator sickness (e.g., [
37
,
115
]) and are
also thought to impact user's sense of “presence” and “immersion” in the VE [
11
].
Perhaps equally important for the application of sensory psychology to VE tech-
nology is an appreciation of the role of efferent information—particularly attention
allocation—to the acquisition of knowledge of one's environment. The literature is
generally consistent with the notion that attention allocation is perhaps the strongest
contributor to spatial knowledge among efferent sources [
18
]. Navigation interfaces
for VEs that demand a user's limited attentional resources are thus especially likely
to impede one's ability to learn about their environment. More generally, because
no VE is yet able to present a perfectly full and veridical sensory experience to its
user, it is important for researchers and VE developers to understand the circum-
stances, tasks, and goals for which these numerous information sources are most
critical.
