Biomedical Engineering Reference
In-Depth Information
groups on the ability to recognize novel and previously seen views were minimal,
not statistically reliable, and in some cases numerically favored the passive learners.
The researchers concluded that the acquisition of spatial knowledge was probably
influenced more by the relative amounts of attention deployed to either the naviga-
tional interface or to the learning of the environment than by active decision making
about where and how to navigate. Similar conclusions were reached by Chrastil and
Warren in their review of the broader literature, who noted that differences between
active and passive learning of environments are probably more heavily influenced
by the allocation of attention than by the ability to choose one's own route through
the environment.
1.4 Relative Influence of External and Internal Sensory
Information
To this point, we have discussed different sources of spatial information in isolation.
Yet we have also noted that in normal real-world situations, multiple sources of sen-
sory and efferent information are mutually available, and that these sources typically
provide overlapping and redundant information. Thus, in understanding the contri-
butions of sensory systems in real-world environments, it is often more relevant and
practical to consider the relative influences of these sources when many are present,
rather than considering the degree to which isolated sources of sensory information
are necessary or sufficient for the acquisition of spatial knowledge. On the other
hand, users of VE systems often do not have access to one or more sensory sources
of information. Thus, in understanding the contributions of sensory systems in VEs,
it is especially relevant to consider the consequences to spatial knowledge acquisition
when some sources of sensory information are absent, degraded, or uninformative.
These two topics (i.e., overlapping sensory information in real world environments
and degraded sensory sources in virtual environments) comprise the outline for the
final section of this chapter. After a brief discussion of the relative contributions of
different sources of sensory information in real-world environments, we close by
summarizing what is known about the impact of unavailable or degraded sources of
sensory information that comes with various types of VE systems.
1.4.1 Sensory Contributions in the Real World
As we have seen in many cases, separate sensory sources are frequently naturally
coupled, and thus can be extremely difficult to isolate experimentally. For exam-
ple, it is difficult for experimenters to dissociate kinesthetic information about neck
movement from vestibular information about the head's rotation. As a result of
these naturally conflated sensory sources, researchers commonly combine various
