Biomedical Engineering Reference
In-Depth Information
sources of sensory or efferent information into broader categories. For example,
many researchers (ourselves included) refer to
body
-
based
information to refer to
the amalgamof vestibular, kinesthetic, and efferent information that is primarily asso-
ciated with self-movement. Others may refer to the amalgamated concept
inertial
information
to refer to the combination of vestibular, somatosensory, and some-
times visual information that indicates acceleration through space. Additionally, the
concept of
podokinesthetic
(or
podokinetic
) information is sometimes used in the
literature to refer to the grouping of somatosensory, kinesthetic, and efferent infor-
mation available about foot contact with the ground during locomotion. Finally,
haptic
information [
60
] derives from the combination of efferent, kinesthetic and
somatosensory information that arises during the active manipulation of objects.
In these ways, groups of commonly occurring sensory sources can be isolated and
examined for their combined contribution to spatial knowledge. It is worth noting
that the advent of virtual reality technology has made much of this research rela-
tively easy to do, although visual-idiothetic dissociations using mirrors [
70
]orprism
glasses [
39
,
99
] have also historically been able to address many of these questions.
A growing body of research has examined the degree to which the presence of
these amalgamated sources of information facilitates the acquisition or enhances
the quality of spatial knowledge when it and others are available. Probably most of
this work has focused on the relative influences of body-based information when
vision is available [
54
,
55
,
73
,
94
,
102
,
103
]. With respect to online tasks that
require transient knowledge, the literature generally shows that body-based senses
do facilitate the acquisition of accurate spatial knowledge of one's environment [
15
,
53
,
116
]. Indeed, as mentioned above, there is some evidence that especially with
respect to acquiring accurate information about turns and orientation, body-based
senses may be necessary [
7
,
55
,
88
].
The relative contributions of visual and body-based senses in tasks and envi-
ronments that require sophisticated enduring knowledge of space, however, is less
clear, and only a handful of studies have addressed this issue. The few that have
tended to conclude that body-based senses contribute minimally to environmental
learning. Waller et al. [
113
] examined the degree to which inertial information facil-
itates the visual system in acquiring configural knowledge of a large environment
by manipulating the amount of valid inertial information available from a 1.6km
car trip through a real-world neighborhood. Three matched groups of participants
received visual information by viewing the trip through a head-mounted display
(HMD). These three groups differed on the presence and quality of inertial (i.e.,
vestibular and somatosensory) information: one group had access to valid inertial
cues, one group had access to invalid inertial cues, and a final group had access to no
inertial cues. The results clearly showed no differences among these groups in their
(fairly accurate) memory of the layout of the environment. Interestingly however,
in a closely-related follow-up study, Waller et al. ([
112
]; see also [
110
]) showed
that the additional idiothetic cues provided by proprioception and efference copy
did make a small but significant improvement in the accuracy of spatial knowledge
acquired from vision. The primary conclusions from all of these studies, however,
has been that the role of idiothetic information in forming an enduring representation
