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Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
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OCR for page 171
7
Geographic Orientation
For a tank crew, developing an accurate mental model of the environ-
ment in which the battle is likely to take place is especially important
during the critical period prior to the onset of a battle. The performance of
this task is mediated by a number of general factors: workload, stress,
fatigue, and environmental conditions. This chapter focuses on some of the
general factors involved in the development of the team commander's model
of the world and how those factors affect his geographic orientation and
workload. Although each of the factors mentioned above mediates a tank
commander's battlefield success, his ability to maintain geographic orienta-
tion (i.e., awareness of one's location in the world) may be the most critical.
The successful tank commander needs to know where he is (present posi-
tion), where he is going (objective), and the position of both friendly and
enemy forces (knowledge of his battle area) at all times, in order to com-
plete the mission. Without this knowledge, situational awareness (knowl-
edge of the dynamically changing environment) may be lost, and comple-
tion of his portion of the battle plan may not be executed successfully. If
the firepower of his team is critical to the success of the mission, the battle
could be lost.
The following pages provide a general review of the theoretical basis of
geographic orientation. Then, drawing the close analogy between naviga-
tion in tanks and in helicopters, we describe the specific navigational tasks
confronted by operators of these two vehicles. The chapter concludes by
placing these tasks in the context of the phases of workload transition.
Although geographic orientation is critical for the tank crew, it is equally
171
OCR for page 172
72
WORKLOAD TRANSITION
important for at least one other transition team, the helicopter, whether an
emergency medical services craft suddenly called for a rescue mission, or a
combat vehicle called into battle. Even in systems in which the world of
concern is small, such as the nuclear power plant, geographic or spatial
orientation will become critical if the operator must diagnose the location
and topology of a fault within the complex interconnections of the system.
WHAT IS GEOGRAPHIC ORIENTATION?
Geographic orientation is not a term defined by Webster. But, using
Webster's definition for geography and orientation, it may be approached as
the sum of two terms: (1) geography: the features, especially the surface
features of a region, area or place and (2) orientation: position with relation
to the point of the compass; familiarization with, or adaptation to, a situa-
tion or environment; specifically in psychology, interpretation of the envi-
ronment as to time, space, objects, and persons. Deaver (1949) defines
orientation as encompassing two psychological senses: awareness of one's
spatial and temporal position within an environmentally defined frame of
reference, with respect to mental rotation.
Thus, we can define geographic orientation as: (1) awareness of one's
relationship to physical features (especially the surface features) of a re-
gion, (2) one's awareness of relative location within that region (e.g., the
center or the edge), and (3) one's temporal awareness of when one should
arrive at locations within that region.
For tank commanders or helicopter crews, geographic orientation refers
to their knowledge of the environment through which they are moving and
to the relationship between where they are, where they should be, and where
they are going. Since the visual scene is continuously changing, geographic
orientation is a dynamic process. It requires navigators to focus their visual
attention on the immediate environment, to maintain directional control and
to avoid obstacles, while simultaneously relating information in the visual
scene (a forward view) to remembered landmarks or those depicted on hand-
held or electronic maps (a downward view). Correlating the outside visual
scene with maps that depict the same area is cognitively demanding and
requires mental rotation and resealing at least. The difficulty of this task is
further increased when objects that are visible in the forward field of view
do not appear on the map, objects are represented by labels or symbols
rather than pictures, and significant landmarks are obscured by other terrain
features, reduced visibility, or both.
How do operators attain and maintain geographic orientation during
operations? Before we can understand this process, we should examine
some of the general factors involved. The following sections will review:
OCR for page 173
GEOGRAPHIC ORIENTATION
173
(1) The issue of constraints on spatial awareness: What physical fea-
tures permit and constrain people's orientation in the world around them?
(2) Spatial frames of reference: How do people represent or understand
their position in the world?
(3) How do factors such as confirmation bias (e.g., expectancies) and
object comparison processes (i.e., comparing map objects or symbols with
viewed objects) affect orientation?
(4) Language: How do people communicate relative positions (i.e., use
verbal information to aid in self-orientation and that of others)?
(5) Timing: How do people remain aware of where they should be
while on the move?
REAL-WORLD CONSTRAINTS ON SPATIAL AWARENESS
The world around us provides a basic structure within which our orien-
tation is defined. It determines both how position and movement can be
defined and measured and how we can come to know our position (i.e., how
we can achieve orientation). According to Shepard (1984), the most perva-
sive and enduring constraints in the world in which we have evolved are
likely to have become internalized in the nervous system As a conse-
quence, such internal constraints may be both so abstract, and so much a
part of ourselves, that we are ordinarily unaware of them. The following
may be considered the fundamental constraints on our experience of geo
. . .
grap tic orientation.
Space is three-dimensional and locally Euclidean. Rigid motion of an
object can be defined by six degrees of freedom: three are translational and
three are rotational. The earth's gravitational field determines a locally
unique upright that is orthogonal to an approximately flat surface. When,
as observers, we are constrained to this surface, we possess: (1) a unique
top (the head) and bottom (the feet) defined by our standing orientation, (2)
a unique front and back defined by the direction we are looking and our
direction of travel, and (3) a basic laterality that defines our right and left
sides (Shepard? 1984) but is less salient than the vertical and fore-aft di-
mensions.
There are more subtle constraints that may be internalized as well. For
example, on a flat horizontal surface, a person may move in any direction
defined with respect to the north-south, east-west frame of reference. North-
south and east-west are not abstract concepts, since they may be internal-
ized with respect to consistent phenomena in the world (e.g., the sun rises
in the east and sets in the west; and when one faces east, north is always on
the left, and south on the right). This frame of reference may be contrasted
to the earth's magnetic field, a natural phenomenon that is not directly
visible but that provides a cue to direction when depicted by a compass.
OCR for page 174
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WORKLOAD TRANSITION
Frames of Reference
Frames of reference are the basic spatial cognitive models by which we
define where we and others are in the world. As such, frames of reference
are obviously critical elements in any account of human navigation. Three
different frames of reference have been proposed as crucial to successful
geographic orientation and locomotion. The first, one's egocentric or ego
frame, is defined with respect to an observer's body (e.g., above/below,
front/back, and left/right).
The second, a container, world, or environmental frame, defines loca-
tion with respect to physical or imaginary world lines or surfaces. The most
familiar container frame, altitude, is defined by the physical dimension of
feet above sea level (up/down) and the more imaginary latitude (north/
south) and longitude lines (east/west) is defined by degrees, minutes, and
seconds. Other container frames can be defined with respect to more con-
crete boundaries, such as tree lines or rivers. The most important feature of
container systems is that their utility diminishes as the observer gets farther
and farther away from the relevant lines or features. Thus, earth latitude/
longitude coordinates would provide a very poor reference system for locat-
ing features on the surface of Mars, and position relative to streets in New
York yields poor localization for places in Trenton.
The third type of reference frame is an object-centered frame, in which
locations and directions are defined relative to fixed landmarks (e.g., mountaintop,
valley, outlook tower). In some ways it shares properties with both the
container and the ego frames. It can be defined with respect to axes run-
ning parallel to the top/bottom, front/back, leftiright, or sides of some ob-
ject. Thus, it is very similar to the container frame in that it has important
world lines or surfaces. However, it is similar to the ego frame as well,
inasmuch as the concept of left/right is involved.
Although all three frames and their associated dimensions can be of
critical importance for an individual, their perceptual availability differs
greatly. For example, the gravitationally defined up/down dimension is
accessible in all three frames by vestibular and visual cues (e.g., objects
typically have perceptually distinct tops and bottoms). However, vestibular
cues are subject to the effects of motion. The front/back direction is also
generally quite salient. Even though front/back is not as invariant a dimen-
sion as gravity, it is useful. FrontAback is available in the egocentric frame
(e.g., what can and can not be immediately seen or approached by natural
locomotion) and given in the object-centered frames (e.g., the distinct front
and back of those objects). The limitation to the usefulness of this dimen-
sion is that, in the egocentric frame, front/back changes with the orientation
of the observer relative to an object while, in the object-centered frame, it
depends on the presence of a natural front and back to the object.
OCR for page 175
GEOGRAPHIC ORIENTATION
175
Rather than being an unwanted complication, the presence of more than
one reference frame may be a prerequisite for navigation. The key to
navigational awareness is a comparison and verification process: Am I (ego
frame) where I should be (world frame)? When these two representations
map onto each other, geographic orientation is maintained; visible objects
correspond to those that are expected to be in a particular location in the
world. When they do not, disorientation will result, which is a potentially
disastrous condition during any combat mission.
For example, Wickens (1989a, 1989b), in his discussion of the multidi-
mensionality of navigational performance, suggested that spatial awareness
(one category of navigation performance) is based on the congruence be-
tween the ego and world frames of reference. The navigator attempts to
maintain congruence between his position and orientation in a world frame
specified by a physical or cognitive map (see Tolman, 1948, for a discus-
sion of cognitive maps) and what he can see in his ego frame (e.g., his
forward field of view). The cognitive representation, which is normally
derived from earlier map study and verbal reports, may be stored as a
spatial representation (cognitive map) or as a route list (a serial list of
verbal descriptors, such as "follow the right fork of the river for three miles
then turn Weston. The congruence model states that two views, or frames,
are congruent if two pairs of points can be brought into a one-to-one rela-
tionship (see Maxwell, 1975, for the mathematical formalization of the con-
gruence concept). In the present case, this means that a person is oriented if
he can match two points visible in the scene with two points on a physical
or cognitive map.
Although both frames of reference are compared to maintain spatial
orientation, they tend to serve rather different functions. For example, we
use the world frame to convey compass heading and cardinal directions
(north, east, south, and west), while we use the ego frame to convey relative
bearing (right, left, front, and back) and clock direction (e.g., aircraft at a
2:00 bearing) when verbally communicating. Similarly, in the control of
locomotion we tend to use the ego frame to characterize the more dynamic,
"inner-loop" variables related to vehicle control (pitch, roll, and yaw) and
obstacle avoidance; we use the world frame to characterize the control of
more slowly changing "outer-loop" variables (position relative to large-
scale terrain features).
Reference Frame Comparisons
Shepard and Hurwitz (1984), in a study of mental rotation during route
following, found that reaction time increased significantly as the route that
was followed departed from an up/down map direction. They suggested
that a compensatory mental rotation of the egocentric frame of reference
.
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176
WORKLOAD TRANSITION
was performed in order to judge the direction of turns as the route deviated
to the left or right.
Two forms of spatial rotation are required for navigation: (1) Physi-
cally rotating a map, or its mental representation, so as to keep the depicted
or imagined direction of travel always pointing directly away from the map
reader; a track-up orientation. This horizontal rotation may be accomplished
by physically rotating a paper map to a track-up orientation or by mentally
rotating a map that was stored in a north-up orientation. (2) Mentally
rotating a two-dimensional plan view of the environment that is perpendicu-
lar to the line of sight to yield an imagined perspective view. This forward
mental rotation is used to compare a mental image with the perspective
forward field of view. Evidence for the reality of these mental rotations can
also be found in studies by Aretz (1988~; Cooper and Shepard (19731; Shepard
and Metzler (1971~; Eley (1988~; Evans and Pesdick (1980~; Harwood (19891;
Hintzman et al. (1981~; Levine (1982~; Shepard and Hurwitz (1984~; and
Sholl (1987~. Each type of rotation requires time, and the processes seems
to be additive.
These studies have shown that the time needed to visually compare two
stimuli increases linearly with the angular misalignment between their ori-
entations. Aretz (1991) found that the time required to mentally rotate a
map to bring it into alignment with the external scene increased from 3.7 to
4.2 seconds as the difference in orientation increased from 0 to 180 degrees
in a helicopter flight simulation.
If one considers this rotation effect in terms of a static environment, the
milliseconds required to perform this task seem insignificant. However,
when considered in the context of a real-world dynamic navigational task,
where object and scene recognition is a continuous process, the magnitude
of this time-consuming process becomes evident and the greater time de-
mands are also more likely to cause errors.
Biases in Geographic Memory
A mentally generated scene used for comparison with a forward field of
view may be stored in memory. Typically, it is derived from map study
prior to the start of a mission. However, it has been found that figures
(such as symbols or icons on a map), especially those with odd shapes, are
difficult to orient in mental space. Therefore, heuristics (rules of thumb)
may be adopted to facilitate the coding and retrieval of the spatial orienta-
tion and location of these figures. Principles of perceptual organization
suggest that people use two such heuristics, rotation and alignment, and that
both lead to subtle, but important, biases.
When it is difficult to remember the exact positions or rotations of
OCR for page 177
GEOGRAPHIC ORIENTATION
177
figures, either or both of these principles of perceptual organization (i.e.,
rotation and alignment) may be invoked for anchoring figures in frames or
shapes in space. When the rotation heuristic is applied, the natural axes of
a figure and the axes of its frame of reference converge. When the align-
ment heuristic is applied, two or more nearby figures group together.
As a consequence of invoking the rotation heuristic, people tend to
remember figures as being more rotated in memory such that their primary
axes are oriented so as to be similar to the principle axes of the reference
frame (Braine, 1978~. Since vertical and horizontal are natural axes for
describing both figure and frame in sensation, perception, and language,
these are the most likely candidates for rotation (Rock, 1974~. Thus, invok-
ing the rotation heuristic will generally result in figures being remembered
as being more vertical or more horizontal than they actually were.
Alignment is related to the phenomenon of perceptual grouping. As a
consequence of invoking the alignment heuristic, people tend to remember
figures that gravitate toward a simpler structural grouping than they actu-
ally possessed. When this heuristic is invoked, arrays of figures are remem-
bered as being more orderly or aligned than they were. What is remem-
bered, then, is a compromise between the actual stimulus pattern and a more
regular, easily remembered pattern (Gogel, 1978~.
These heuristics may be invoked during the formation or encoding of
representations of the visual world, during the storage of these representa-
tions, as well as in the later use of these representations. They are approxi-
mation techniques that facilitate memory, but at the expense of distortions
of locations and orientations. The heuristics may also allow inferences
when information is incomplete; for instance, when comparisons are made
across regions that have not been stored together. In these cases, best
guesses must be made about relative orientation or alignments of stored
representations. For example, Tversky (1981) found that these biases af-
fected performance in map reproduction, recall, and recognition memory
and that they were adopted in storage, when spatial positions were difficult
to encode, as well as in inferences to fill in gaps of knowledge. Tversky
presented evidence for systematic distortions in memory for real-world maps,
artificial maps, local environments, and visual forms. For all of these di-
verse stimuli, the distortions have the same characteristics reflecting align-
ment and grouping heuristics. For example, the position of stars is remem-
bered by aligning them with one another to form meaningful structures (i.e.,
constellations).
The alignment and rotation heuristics have been demonstrated in the
way people remember familiar, naturally occurring stimuli, as well as for
new information acquired from artificial stimuli (Palmer, 1980~. They have
been demonstrated for information acquired from artificial navigation (e.g.,
OCR for page 178
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WORKLOAD TRANSITION
path following in a laboratory study) of environments, information acquired
from maps for visual forms, as well as geographic entities (Stevens and
Coupe, 1978~.
Particularly important for navigation is the finding that spatially ex-
tended stimuli (e.g., highways and mountains) induce their own axes in the
normal course of perception (Braine, 1978; Howard and Templeton, 1966;
Rock, 1974~. These coordinate axes, which can serve as an induced con-
tainer frame, may interact with object-centered reference frames. This causes
the container axes and the object axes to appear, or be imagined, to be in
greater alignment than they actually are. For example, during a recent field
study, emergency medical services (EMS) helicopter pilots were asked to
draw maps of their service areas. Their maps depicted highways that gener-
ally parallel northwest to southeast mountain ranges as straight lines (Battiste
et al., 1989~. The east and west ranges of hills in the San Francisco Bay
area serve as a container for this area, thus spatially extended stimuli (high-
ways, powerlines, etc.) are remembered as being more aligned with these
hills, than they actually are. But this does not affect their ability to perform
required piloting tasks.
Hierarchical anchoring is another important heuristic that people use to
help them remember geographic information. For example, Stevens and
Coupe (1978) presented evidence that people remember the position of large
geographic units, such as states, remember which cities belong to which
states, and then use the location of the state to remember the locations of
the cities. However, systematic distortions may result from using this strat-
egy. For example, subjects report that Reno is farther east than San Diego.
However, comparing these two cities on a map, one can easily determine
that Reno is the more westerly city. ~^ his occurs because the state of Nevada is
thought to be east of California. Since Reno is a city in Nevada, it is thought
to be east of any city in California. Thus, this heuristic makes it difficult to
directly compare locations nested within different higher-order units.
While Tversky (1981) presented evidence for systematic distortions in
remembered location and orientation, other researchers have demonstrated
systematic distortions of distance relations among elements. Thus, two
points are judged to be closer when they are within the same object or
contour (container frames) than when they are in different objects or con-
tours (container frames) (Coren and Girgus, 1980~. For example, a distance
within a large city would be judged closer than an equal distance between
two cities.
Reference points also affect distance judgments. Distances between
objects and a point of reference that is near are overestimated, while dis-
tances between objects and a point of reference that is distant are underesti-
mated. That is, spatial discrimination is greater when closer to a point of
reference.
OCR for page 179
GEOGRAPHIC ORIENTATION
179
Reference points can also induce asymmetry in distance judgments.
Ordinarily, places and landmarks (i.e., important points of reference) are
judged to be closer when places are compared with landmarks than when
landmarks are compared with places (Sadalla et al., 1980~. That is, when
proceeding toward a landmark from a place, the distance would be judged
closer than when proceeding from the landmark to a place. Thus, reference
points and figural properties also affect how spatial knowledge is organized
in memory and yield systematic errors in distance judgments.
The problem of remembering spatial locations of figures is similar to
the problem of remembering the order of a list of verbal items; for both,
structure promotes memory but may induce distortions. Whether or not
these biases exert significant influence on the absolute recognition proce-
dure employed in a navigational task is unclear. For example, would a tank
commander or a locomotive conductor become confused if the viewed cur-
vature of a mountain is greater than the simplified (i.e., straightened) men-
tal representation of the mountain?
Another potential distortion is related to the way people forget particu-
lar image features that might be used for object comparisons. An assump-
tion made by some researchers in this area, which is supported by pilot
interviews, is that during map study, people imagine a three-dimensional
representation of a feature depicted on two-dimensional maps. These three-
dimensional images are later remembered for comparison with their view of
the "outside" scene (Eley, 1988~. Do people, during map study, imagine
three-dimensional forms for comparison with their forward field of view?
Do they forget these distinctive shapes when comparing their mental repre-
sentation to the actual figure? How well is seasonally variable ground or
vegetation texture imagined when studying a map, and how much of this
detail is remembered?
Biederman's (1987) work on the basic components of object recogni-
tion may provide a useful framework for understanding landmark memory
and forgetting. Also relevant here is the fact that memory of object shapes
tends to be biased toward the symmetrical representation, as mentioned
earlier.
Language
As studies in the field of linguistics (Fillmore, 1968) and psycholinguistics
(Clark, 1973) make clear, the fundamental spatial facts of the world are
reflected not only in our perceptual and cognitive structures, but also in the
way we talk about the world. For example, there is considerable evidence
suggesting that the primacy of the up/down dimension affects not only how
we see and think about the world, but also the very words we use to talk
about the world.
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WORKLOAD TRANSITION
With regard to language, children learn and successfully use terms per-
taining to up, down, front, and back long before they master terms pertain-
ing to left and right or to north, east, south, and west. Also, the terms up
and down are universally used to refer to any directions in the horizontal
plane (e.g., he traveled up North, they went down South, "he walked up to
the front of the room," "they walked down the street together".
Clark (1973) also noted the significance of referring to the direction of
the reference object as up (e.g., they climbed up to the top), suggesting that
things above the ground plane are snore accessible than things that are
below. Therefore, the upward direction seems to cognitively dominate the
downward direction.
As global navigation grew in importance and with the invention of the
magnetic compass, the unique poles of the earth became more appropriate,
accessible, and invariant reference points. And since most of the global
navigators and map makers came from the northern hemisphere, the asso-
ciation between spatial proximity and the absence of linguistic markings
would favor the north pole as the reference point for up. These reasons can
somewhat explain why the direction of north has come to mean up in navi-
gation and communication among navigators, and also why north is conven-
tionally oriented at the top of maps.
In a simple universe, with only one natural frame of reference (egocen-
tric frame), one might not have a need to imagine rotations in space. How-
ever, our daily world, and the world of pilots and tank crews, coordinating
with each other and with fixed bases on the ground, are greatly complicated
by the fact that people who must coordinate their activities may occupy
many different ego frames of reference over time (as a result of locomotion)
and space (there may be more than one moving observer). Thus, as two
vehicles move independently about a common terrain, the relations between
the principal directions of each frame constantly change. Although the
upward vertical direction remains aligned across all of these frames (ego-
centric, object, and container), what was on the "right" may move to the
"left" (if the viewer moves) or what is on the right for one observer may be
on the left for another because it is perceived from a different vantage
point. Mental rotations of perceived and expected scenes or placing our-
selves in the perspective of another may facilitate anticipation, planning,
and communication in such a world.
Timing
While orientation in space is an important issue addressed by the con-
cept of frame of reference, the equally important issue of orientation in time
is not. Many aspects of the tank commander's duties involve timing: arriv-
ing at initial battle position on schedule, crossing way points on time, and
OCR for page 181
GEOGRAPHIC ORIENTATION
181
coordinating arrival times with other teams. It is the tank commander's
responsibility to monitor the passage of time during maneuvers. Although
most commanders wear watches, continuous monitoring is not possible be-
cause other tasks require their attention. Thus, temporal orientation in-
volves more than whether or not the tank commander has a watch.
How do people maintain temporal orientation? Gibson (1968) argues
that there is no such thing as the perception of time, but only the perception
of events and surfaces. Events, in particular locomotion, do not occur in
space but in the medium of an environment that is rigid and permanent.
Gibson argues that abstract space is a "ghost" of the surface world, and that
time is a ghost of the events of the world. Following his logic, it is not
difficult to understand that humans are not very astute time estimators.
However, humans are very good at perceiving events. Pilots, during low-
level flight, know when to start looking for features in the terrain that they
plan to use as orienting landmarks. Typically, when clocks are not used,
pilots' estimates of clock time are based on relative distances and speeds of
travel. This method of keeping track of time (e.g., tracking physical events)
is very different from keeping track of clock time.
There is considerable support for Gibson's belief that time is a ghost
abstracted from event structure. For example, Hart (1978) obtained evi-
dence suggesting that people do not perceive time directly but employ strat-
egies for monitoring its passage. She used subjective time estimates as
indices of workload and found that commercial airline pilots' abilities to
actively keep track of time varied as a function of the demands of other
flight-related duties. When pilots were asked to estimate 10-second inter-
vals, Hart found that the estimates increased from about 10 seconds with no
competing activity to 14 seconds in the presence of a difficult concurrent
tracking task. She also found that the variability of their estimates in-
creased with higher task demands. Hart asserted that, as task demands
increased, there is less attention available for active time estimation. Simi-
lar results were obtained during a simulation conducted at Wright Patterson
Air Force Base (Gunning, 1978~.
During the active mode of time estimation, there are many timekeeping
techniques: tapping, counting (both aloud or silently), using remembered
events, counting heartbeats, etc. These methods are used to fix an individual's
attention on the passage of time and makes the process more concrete.
However, these externalized methods are easily disrupted by more compel-
ling activities and are impractical in an operational situation.
In response to the problem of estimating time under very high levels of
workload, Hart suggested that people seem to switch from an active produc-
tion mode to a "retrospective mode" of time estimation. With retrospective
estimation, people use the number of events that occur during an interval as
a measure of the amount of time in that interval. In her study, Hart found
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GEOGRAPHIC ORIENTATION
187
as terrain features and relationships will not correspond in the expected
sequence.
Thus, maintaining geographic orientation requires helicopter and tank
crews to continuously correlate the visual scene with the map. To do this,
they must accurately estimate their speed and distance traveled. Estimates
of when to begin looking for a landmark, when a choice point has been
missed, or what features should be visible at any point in time are based on
subjective estimates of the distance traveled and time elapsed since the last
known location.
When operating at night, tank and helicopter crews rely on night vision
devices (that intensify light or display infrared imagery) to provide them
with information about the external scene. Although they could not perform
required missions as well without these devices, their use imposes consider-
able additional load on the pilots: field of view is limited, acuity is re-
duced, depth cues are distorted, subtle textures necessary to identify a par-
ticular feature may be missing, and objects or terrain features may look
very different than expected. Furthermore, greater navigational precision is
required at night; obstacles that can be seen and avoided during the day may
be invisible at night. Thus, pilots rely on maps to spot potential obstacles.
However, this information is useful only if they know exactly where they
are. For these reasons, maintaining geographic orientation becomes signifi-
cantly more difficult, and overall performance capabilities may be reduced.
For example, pilots are more likely to fly slower and higher at night, and
over sand, where texture supporting accurate distance estimation is absent.
In tanks and helicopters, crew members communicate with each other
through an intercom system (high ambient noise levels and physical barri-
ers, in some cases, preclude direct conversations) and with other helicop-
ters, ground personnel, etc., through radios. Navigational and geographic
orientation information is usually conveyed verbally, although crew mem-
bers may use gestures as well (e.g., point to features in the environment or
on a map). In helicopter nap-of-the-earth flight, navigation may take as
much as 90 percent of the navigator's time, and communications between
the pilot and navigator about navigation, 25 percent of both pilots' time.
Army aviators use 1:50,000 scale maps that depict terrain contours (e.g.,
hills and valleys), vegetation (e.g., fields and groves of trees), bodies of
water (e.g., rivers, streams, and ponds), and some cultural features (e.g.,
roads, buildings, bridges, water tanks, and towers). During premission planning,
helicopter or tank crews plot their route on the map, identify critical choice
points, and select additional features that they will use to verify their posi-
tion. In flight, the navigator follows the route of flight on the map, giving
the pilot verbal cues about what he should see, when he should begin or end
a turn, and potential obstacles. In addition, the navigator scans cockpit
instruments, verbalizing relevant information to the pilot. The pilot gener
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WORKLOAD TRANSITION
ally keeps his eyes focused outside the cockpit, telling the navigator what
he sees in the external scene and verifying that he does (or does not) see
specific landmarks described by the navigator. In a tank, the commander is
responsible for navigation, passing verbal steering commands to the driver;
particularly when the tank is buttoned up because the driver's field of view
is too restricted to maintain geographic orientation.
Helicopter or tank crews use or mix a number of different frames of
reference when exchanging information among themselves or transmitting
to another vehicle: (1) ego-reference/spatial (e.g., a landmark is in front, to
the right, or to the left of the pilot; the driver should turn right or left); (2)
ego-reference/clock position (e.g., a feature is at the observer's or recipient's
2 o'clock position); or (3) world-reference/compass heading (e.g., the pilot
should look for a stream running north-south; an enemy tank is located 5
miles northwest of a friendly tank; another vehicle should turn 20 degrees
to maintain a new heading of 280 degrees).
Ego-referenced directions are the easiest to process (Aretz, 19901; they
require minimal mental transformation or interpretation. Clock positions
are less intuitively obvious than right/left directions, although they provide
more precise information. However, clock position may be ambiguous if
the sender's and receiver's points of reference (i.e., head position) are sig-
nificantly different. Furthermore, extracting spatial information given in a
verbal form may require additional mental transformations. When giving
ego-referenced directions, the originator of the message must mentally project
himself into the point of view of the intended recipient, an activity that
imposes additional cognitive demands and is subject to error. In both the
tank and helicopter environment, the reference frame problem is compounded
because the direction of travel of the vehicle may not correspond to the
direction the operator is facing.
Spatial information that is world-referenced (i.e., to a numeric or verbal
compass position) is more precise than other forms and does not require
that the sender or recipient project themselves into another's ego-reference.
However, steering commands referenced to compass position presuppose
that the recipient knows the current heading. In helicopters, the pilot re-
sponsible for flying may have no idea what his current heading is because
he is focusing on the external scene, rather than on the instruments. Thus, a
flight navigator might couple an ego-referenced command (e.g., turn right)
that requires minimal mental transformation with a world-referenced modi-
fier (e.g., turn right; now you're heading due west) to improve the pilot's
orientation. In tanks, there is no compass on the instrument panel, and the
metal body of the tank interferes with the accuracy of hand-held compasses.
Therefore, compass headings are not used for steering commands in tanks.
In addition to the problems associated with the use of different refer-
ence systems, tank and helicopter crews often operate in unfamiliar envi
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GEOGRAPHIC ORIENTATION
189
ronments in which crew members do not share a common knowledge base
about the names and appearance of significant landmarks. Thus, informa-
tion about these landmarks must be transferred on the basis of their physical
appearance (e.g., a small round pond, a dry river bed, a saddle-back hill),
rather than by unambiguous names (e.g., Jones' farm, White Mountain,
Route 50~. Given the potential differences in personal experience, descrip-
tive terms may have very different meanings for different crew members.
For example, what looks like a pond to one may look like a lake to another.
A 500-foot hill may look like a mountain to a Midwesterner, but a person
from Colorado would describe it as a small hill, and so on. Furthermore,
lack of familiarity with local vegetation may make the description process
particularly difficult; it is easier to identify a grove of trees by name than by
physical appearance.
The preceding description of navigational demands of tanks and heli-
copters can also be interpreted within the more theoretical framework of
research on geographic orientation. In the following section we employ this
framework to introduce laboratory research results that have implications
for navigational performance in armored vehicles.
NAVIGATION AND WORKLOAD TRANSITION
When people travel long distances over indistinctive terrain, they often
either physically mark the terrain or mentally accentuate whatever distinc-
tive features they can find in the environment (Lynch, 1960~. Helicopter
pilots and tank commanders during premission planning use both object and
container reference systems. On a map, which is usually oriented north-up,
distinctive objects (terrain features) are selected to delineate a planned route
to the destination and to identify features or objects that will serve as ori-
enting stimuli for different route segments. Additional large-scale features,
usually linear (e.g., a mountain, valley, or tree line) are selected to contain
the mission area. During the mission, the tank commander or helicopter
pilot will use all three frames of reference-ego, object, and container. The
ego reference system, the most proximal, is used for local course guidance
(e.g., keeping the vehicle moving toward the goal) and obstacle avoidance;
hence, it is particularly relevant for communications with the driver. The
object reference system, a less proximal system, is used to identify current
location and general course guidance (direction of travel) to the next object
or waypoint. Finally, the container, a more distal reference system, is used
to determine the degree of lostness (e.g., when the container boundary is
reached prior to a planned location or waypoint, the tank commander is no
longer sure of their precise position).
Helicopter pilots and tank commanders use both object and container
reference systems during the planning and execution of their missions. The
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WORKLOAD TRANSITION
object reference system is used to plot a planned route through an area. The
container reference system is used to determine the mission boundaries.
During the mission, the object reference system is used to determine exact
position to maintain geographic orientation. The container reference system
is used to determine the degree of lostness (e.g., whether they have gone
past a location that they had planned to use as a waypoint or location fix
and are now no longer sure where they are).
Multiple reference systems can provide a tank commander with flex-
ibility. To the extent that environmental conditions (battlefield conditions)
vary, a tank commander must invoke different strategies to accommodate
this variability.
The Premission Phase
During the premission phase, the tank commander is assigned an area
of responsibility and battle mission objective. He has to develop a mental
model of the area where the battle will be joined. This model includes
memorizing the area based on maps (north-up) and verbal reports given by
the battalion staff intelligence officer. From these reports, the tank com-
mander must develop a plan of attack. This plan consists of a spatial
representation of the terrain and the locations of all friendly and known
enemy positions. From this spatial representation (usually developed as
overlays on a map), the tank commander must select a route to his team's
initial battle position and on to the final objective. While selecting the
route, waypoints will be selected to break the route into segments. These
distinctive features allow the tank crew to periodically update their knowl-
edge of where they are (so they will not go too far in the wrong direction),
recognize points where course changes will be made, and compare planned
versus actual time taken to move between points (to stay on schedule). This
plan is developed in conjunction with or communicated to battalion head-
quarters and platoon commanders. The workload during this phase of the
mission depends on the amount of time available to accomplish these tasks
and the quality of information available. The planning phase is informa-
tion-intensive. In developing a mental model of the mission area, the tank
commander might mentally rotate the north-up map into a track-up perspec-
tive to visualize the route and to brief the platoon commanders. In commu-
nicating the plan to battalion headquarters, it is likely to be expressed in
polar coordinates with reference to a north-up map, so the plan can be
correlated with that of other teams. However, in communicating the plan to
platoon commanders, the information is likely to be expressed from an ego-
centric perspective: first platoon will be on my right, second platoon to my
left, etc.
During the planning phase of a mission, the tank commander's workload
. . ~.. .
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GEOGRAPHIC ORIENTaTION
191
is driven primarily by the difficulties of incorporating vast quantities of
information, both verbal and spatial, into a spatial (cognitive or paper) map.
Aretz (1990), in his study of spatial cognition and navigation, found that
map complexity accounted for most (7 percent) of the explained variance in
the task. Thus, as map complexity increases, so does processing time and
workload. Also, the need to mentally rotate different map frames to com-
municate information both up and down the chain of command would affect
workload.
The Operational Phase
During the operational phase, the tank commander must move his forces
from their current location to their initial fighting position. He must con-
tinually correlate his position in the world (forward field of view) with his
map route (world view) to maintain geographic orientation. This is accom-
plished by orienting the map to correspond to the direction of movement
(track-up) to align the two frames of reference. During this phase, time
estimation is very important for determining when objects or features in the
terrain, which are used to confirm geographic orientation, should appear.
Also, the tank commander must update his estimated time of arrival (ETA)
at the initial fighting position based on his estimate of how far he has gone
and how long it is likely to take to cover the area remaining. This may be
critical, if the initial engagement time must be coordinated with other teams.
Transition From Rear Staging Position to Initial Fighting Position
The accuracy with which a tank commander must know his team's
position during the move to the initial point depends on the proximity of
other friendly and enemy positions and the degree to which a precise transi-
tion to the initial fighting position is critical to mission success. That is, if
the team is trying to stay masked during the transition, then required accu-
racy could be very high; if surrounded by enemy forces, maintaining a route
designed to maintain cover is critically important. During this phase, com-
munications between the tank commander and either platoon or battalion
commanders would be very different. For instance, situation reports to
battalion headquarters would be given in terms of polar coordinates (world
view), while reports from each platoon commander might be given from an
ego-centric view (right/left, front/back, or clock positions) of each tank. In
the latter case, the tank commander must integrate information from each
ego-centered perspective to form a coherent picture of the entire situation
into a single frame of reference.
The workload during this phase of the mission is likely to be moder-
ately high. The tank commander must perform multiple tasks, in parallel
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WORKLOAD TRANSITION
and serially: (1) continuously determine his own position and the relative
position of members of his team, other teams, enemy forces, and his objec-
tive; (2) estimate and update the time between waypoints and his ETA at the
initial fighting position; (3) communicate his own and other positions up
the chain of command; and (4) communicate route and mission changes
down the chain of command. The difficulty of these activities is deter-
mined by the speed at which the situation unfolds, the degree to which it
unfolds according to plan, the availability of salient cues to maintain orien-
tation, and, most critically, the positional accuracy demanded by mission
requirements. The amount of time and effort spent in acquiring geographic
knowledge of terrain during the premission phase is also relevant, as this
information is unlikely to change during the course of the battle and pro-
vides the basic context within which other dynamic events occur.
The Preengagement Phase
Upon arrival at the initial battle position, particularly if the mission
calls for immediate engagement, the degree to which previous phases have
been completed successfully (e.g., the planning phase and the transition to
the initial position) influences the workload experienced during the battle
phase. If the team has successfully completed the previous phases, the
battle plan could be implemented without further changes. Thus, workload
during this phase would be driven by the accuracy of estimates of enemy
strength and the degree to which the tank commander's plan took them into
account. If the team arrived late, or at the wrong location, the workload
during this phase could be very high. In addition to coordinating his team's
actual position with other teams, the tank commander may also have to
coordinate with infantry and artillery units (to develop a revised plan). This
might require extensive communications using different map frames of ref-
erence. Even if the tank commander executed the first part of the plan
correctly, he may haste to develop a new battle plan in response to the
environment (terrain, time of arrival day or night, enemy activity, etc.) or
to a change in the mission. His communications load during the develop-
ment of a new plan would be very high: it must be transmitted both up and
down the chain of command.
During a battle, maintaining geographic orientation is critical to the
identification of friendly forces and enemy targets. If artillery or close air
support is needed, the tank commander, through his fire support officer,
would determine where and how much artillery or close air support is re-
quired, in relation to their current position. Again, this requires a transla-
tion between a world view (artillery and close air support) and the egocen-
tric view (tank commander and fire support officer). Since the commander's
tank, and those of his team, are in the battle area, accurate estimates of
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GEOGRAPHIC ORIENTATION
193
friendly and enemy positions and accurate communication of those posi
. . . .
tons are critical to survival.
The Post-Mission Phase
Whether the battle is won or lost, situation and logistics reports must be
compiled. First, the tank commander must assess his team, their position in
relation to the battle plan, their losses in equipment and men, etc. The
verbal reports from individual tank and platoon commanders must be corre-
lated with a map of the area. When receiving reports, the tank commander
may orient his map either track-up or north-up. Orienting the map to corre-
spond to the frame of reference of each reporter might facilitate interpreting
the (ego-centric) communications of team members (e.g., the platoon on the
right reports that the enemy forces at their 3 o'clock position have been
eliminated, etc.~. A north-up perspective (i.e., the world view) would facili-
tate communication up the chain of command, wherein the battalion com-
mander must evaluate the report of each team in relation to other teams'
successes or failures. The workload during this phase would be influenced
by the ease with which a commander could integrate information provided
in different frames of reference into a coherent picture of the overall situa-
tion.
SUMMARY
Geographic orientation plays a major role in the success or failure of
most tank operations. Platoon and tank commanders must continually up-
date their position by comparing different map frames of reference (e.g.,
their forward view of the world to a paper or remembered map) to deter-
mine their position in the world. The level of congruence between different
reference frames (and the mental rotation required to bring them into align-
ment) will be a factor in determining the time and difficulty of the geo-
graphic orientation task, as well as the likelihood of errors. Terrain charac-
teristics, required accuracy, familiarity, and planning also affect the level of
workload associated with geographic orientation and navigation.
To reduce the tank commander's workload, technological innovations
such as electronic chart displays (ECD) and premission planners, which can
be taken from the mission briefing and downloaded in ECD computers,
should be introduced into tanks. (Their utility has been demonstrated in
helicopter operations Cote et al., 1985.) Low-cost electronic chart display
systems coupled with global positioning satellite (GPS) receivers are being
developed to determine and display the exact position of a vehicle superim-
posed on a map, a task currently performed by the tank commander using
paper maps, at a considerable cost in time and cognitive effort. The cogni
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WORKLOAD TRANSITION
live demands of the geographic orientation/navigation task could be re-
duced by the installation of an electronic chart display system that is de-
signed to maximize the degree of congruence between the map format, the
terrain it depicts, and the tank commander's model of the environment.
Different display formats will facilitate the performance of different tasks.
The following list of features should allow the system to be both compatible
with task requirements and the tank commander's internal model:
(1) The system should support both north-up and track-up map formats.
The north-up format will facilitate mission planning (multiple missions can
be planned and correlated on the same map) and communication between
individuals who do not share the same perspective view of the terrain (e.g.,
headquarters and artillery). Communication between individuals who do
not share the same visual perspective must rely on map coordinate data
when transferring information.
The track-up format will facilitate wayfinding, locating targets, and
communication between individuals who share the same perspective view
of the terrain (i.e., the tank commander and the driver'. Individuals who
have a shared visual perspective can communicate using visual terrain fea-
tures correlated with map information to support information transfer.
(2) The planned route and the current position of the vehicle should be
depicted on the map display. Depicting the planned route and the vehicle's
current position on the map eliminates the need to micronavigate between
waypoints (thus, the driver's task becomes one of obstacle avoidance and
compensatory tracking between waypoints) and facilitates reorientation if
the tank becomes lost or makes an unscheduled detour.
(3) Map features selected by the tank commander during mission plan-
ning to identify route transition points (waypoints) or to aid in maintaining
geographic orientation should be depicted on the ECD system. The degree
of congruence between the map and the terrain, and also the cognitive
compatibility between map depictions and terrain features, may be improved
if iconic symbology selected by the tank crew during mission planning is
used.
(4) Through the use of color and shape coding, contour line information
can be accentuated and thus becomes more iconic.
(5) Compass information derived from GPS data, scalable range marks,
latitude and longitude, bearing to and from selected points on the display,
and variable map scales should be available on demand.
Also, electronic maps must depict the sort of features tank commanders
and helicopter pilots actually use for geographic orientation, represented in
a form that is most compatible with the way the feature will appear in the
forward scene. By reducing the workload associated with navigation, all of
the features should allow the tank commander more resources to deal with
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GEOGRAPHIC ORIENTATION
195
tactical decision making, planning, communications, and team coordination,
issues addressed in the next three chapters.
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Representative terms from entire chapter:
tank commander
