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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 1
Summary
Systems in a variety of settings can be characterized by having a team
of operators, functioning for some period of time under relatively routine
conditions, then being abruptly confronted with abnormal and sometimes
emergency circumstances to which they must rapidly respond in an appro-
priate manner. We term these features the team transition situation. We
begin with some examples of these types of teams:
(1) The crew of a nuclear power control room becomes aware of a
transient event in the reactor and must attempt to establish the appropriate
procedures to maintain or restore plant safety.
(2) The crew of a commercial airline suddenly becomes aware of a
life-threatening malfunction. Again, the team (i.e., flight deck personnel,
maintenance personnel, and air traffic controllers) must rapidly perceive,
problem solve, and respond to ensure the safety of the aircraft.
(3) Personnel in a hospital emergency room, on a quiet night, are sud-
denly confronted with victims of a serious automobile accident. Rapid
problem solving and perhaps prioritization of causalities must be coupled
with the precise exercise of procedural skills and coordination with the
emergency room staff.
(4) An emergency medical service (EMS) team is suddenly called on in
the middle of the night to make a helicopter flight to pick up a critically ill
patient. The weather is bad, and the destination is unfamiliar.
(5) An MlA1 army tank crew stands ready and waiting at the edge of a
battlefield, its crew of four having waited in a state of combat readiness for
OCR for page 2
2
WORKLOAD TRANSITION
36 hours. Suddenly hostile shots land close by, and the crew must immedi-
ately become an effective fighting unit.
For many of these kinds of teams, there is evidence, both formal and
anecdotal, of failures of the team to effectively manage crisis situations.
Three Mile Island, the crash of Eastern Airlines L1011 into the Everglades
in 1972, and the Exxon Valdez incident are graphic examples. Against
these failures, however, may be balanced the many instances in which a
team has successfully managed the crisis. The ability of the pilots of the
United Airlines flight, which suffered a total hydraulics failure near Sioux
City, Iowa, is a salient example.
BACKGROUND
In 1988, in response to a request from the U.S. Army Human Engineer-
ing Laboratory, the Committee on Human Factors of the National Research
Council undertook a project to provide advice and guidance on the effects
of prolonged work underload on the subsequent performance of critical
tasks and on approaches that could be employed to offset or compensate for
decrements in performance that otherwise might occur. This information
was requested in anticipation of Army plans to develop tanks with smaller
crews than those currently found in MlA1 tanks. Crew downsizing would
result in some tasks being automated or redistributed among remaining crew
positions. During active deployment, the reduction in crew size is likely to
increase workload, thus increasing the potential for performance failures
and errors unless compensatory measures are devised. A concern of the
Army was whether the response to high workload would be further exacer-
bated when it follows long periods of waiting.
Although the concept of workload transition has been given little, if
any, attention and even less research emphasis, it is nevertheless an impor-
tant problem encountered in many work settings such as those identified
above. This generic aspect of suddenly having to perform important activi-
ties after a period of relative or complete inactivity lends special interest to
the problem posed by the Human Engineering Laboratory. While some
underload situations may lend themselves to administrative solutions, the
uncertain environment of tank combat requires research solutions that iden-
tify those technologies that may be used to offset the possibility of negative
effects on performance.
The objectives of this study were to: (1) review the concept of work
underload and assess the state of research knowledge and its effects on
subsequent high-workload task performance; (2) evaluate the components
of the critical high-workload onset tasks to assess which components are
most likely to be vulnerable to decrements from prior underload or the
OCR for page 3
SUMMARY
3
sudden onset of workload; and (3) identify and evaluate techniques that
might be used by designers to compensate for, or offset, likely performance
decrements.
A cursory analysis of the work underload problem reveals that several
partially related domains of research are relevant to the problem: workload,
stress, sleep loss and circadian rhythms, vigilance, geographic orientation,
cognitive task management, decision making, crew communications, leader-
ship and team coordination, and training.
ANALOGOUS SYSTEMS
When empirical data are scarce, insight and advances in knowledge
may be achieved by sharing knowledge from similar systems or paradigms.
However, the application of conclusions drawn from one domain to another
must proceed cautiously and identify the ways in which the two domains
are similar or different. There are five general features of similarity in the
team transition process: time, structure of the event, environment, personal
risk, and organizational structure. Time refers to the abruptness with which
a crisis transition unfolds, the expectancy or perceived probability that a
transition will occur, and the length of time that a crew must remain on
watch before an event may occur. The structure of the event refers to the
extent to which its nature is predictable and whether the desired response
can be effectively preprogrammed. The environment describes the physical
conditions. Personal risk is the extent to which the team is exposed to risk
of personal injury or death, both to themselves and to others. Finally,
organizational structure has three subcomponents: team structure or com-
mand authority, team integrity or continuity of team membership over time,
and autonomy or extent to which the team functions alone rather than in
close coordination with a higher organizational structure.
Characteristics of commercial airline crews, nuclear power plant con-
trol room crews, railroad freight train crews, merchant and military ship
crews, natural disaster relief teams, emergency medical services crews, and
trauma center and emergency room crews are briefly presented, followed by
a few cautious generalizations which can be extended to the tank environ-
ment. First, in each system, appropriate duty schedules are very important.
At present, these appear to be lacking in ship, railroad, and trauma center
systems, to name but a few. In most of these systems this factor has been
identified as contributing to numerous accidents.
Second, lack of a communication protocol appears to have serious con-
sequences on crew performance. Many crews operate in more isolation
than is advisable. When the triggering event is complex or unstructured,
continuous situation awareness in the pretransition period is likely to in-
crease the probability of more efficient and adaptive problem solving during
OCR for page 4
4
WORKLOAD TRANSITION
the transition. This situation awareness is also likely to reduce the crew's
stress and perceived workload.
WORKLOAD
A characteristic of most post-transition periods is a large number of
task demands, often imposed with very severe time constraints. These tasks
are often characterized by the description of high workload. Although workload
and performance are clearly related, their relationship is much more com-
plex than originally thought.
From mission requirements and models of human behavior, nominal
workload profiles can be developed for different equipment and missions.
However, unexpected events, environmental stressors, and other factors may
alter significantly the workload a particular crew experiences. Considerable
research has been performed to understand, manipulate, and measure workload
of specific tasks or intervals of time. However, relatively little is known
about the effects of moving from one level of workload to another. Differ-
ent crews cope with such changes in different ways, but neither optimal
strategies nor the performance consequences of suboptimal strategies have
been identified. Regardless of the specific sources of workload, adequate
training and preparation, adopting strategies and tactics most appropriate
for the situation, effective leadership and effective crew coordination can
counteract some of the detrimental effects of imposed task demands, mov-
ing from one mode of behavior to another, environmental stressors, and
fatigue.
STRESS
The post-transition phase will impose a substantial degree of stress,
incorporating time pressure at a minimum, but also danger and various
other environmental stressors. Stressors may include features of the work
environment such as noise, vibration, heat, poor lighting, toxic substances,
and acceleration, as well as psychological factors such as anxiety, fatigue,
and danger. These stressors may have different manifestations: subjective
experience, physiological change, and performance decrements. The differ-
ential effects of many environmental factors have been demonstrated on the
performance and physical workload of various types of tasks. Psychologi-
cal stressors related to danger and anxiety have also been associated with
specific changes in cognitive processes. Stress, similar to workload, has
been found to interact with a host of factors and affect performance in
complex ways; however, there are a variety of techniques that may be adopted
to minimize the degrading effects of stress on human performance: design
solutions, the use of strategies, and training.
OCR for page 5
SUMMARY
s
SLEEP DISRUPTION AND FATIGUE
Performance following workload transitions is affected by three factors
related to the daily cycle of sleep and wakefulness: a 24-hour circadian
rhythmicity (indexed by body temperature), sleep deprivation, and sleep
inertia. Psychomotor and cognitive performance on a variety of tasks in
round-the-clock operations is at its worst during nighttime hours, generally
reaching a nadir just before dawn. Circadian variations in alertness, cogni-
tive performance, short-term memory, sleep tendency, spontaneous sleep
duration, awakening, and rapid eye movement sleep propensity all remain
closely coupled to the body temperature cycle.
Many studies have documented the deleterious effects of both sleep
loss and misalignment of circadian phase on performance and safety. Tasks
that require consistent, sustained alertness or perceptual-motor activities
were found to be most sensitive to sleep loss in a 48-hour field test; and
self-initiated activities, such as planning and maintaining situational aware-
ness, degraded most quickly.
There is no known technique available to sustain human performance at
an acceptable level for 72 continuous hours; however careful planning can
result in the development of countermeasures, such as caffeine and other
stimulants, increased physical activity, naps, monetary incentives, diet, and
intensive social contact that can reduce the impact of sleep disruption on
the performance of crew members. While these techniques can mitigate the
deterioration of performance on the first night of sleep loss, none is effec-
tive in overcoming the impairments of performance that occur on the sec-
ond or third nights of continuous operations.
VIGILANCE
A large portion of the responsibility of armored vehicle teams, and
indeed the teams of many analogous systems, prior to transition is simply to
monitor the environment for events that might signal the need for the team
to mobilize into action. This is particularly true for gunners who bear the
primary responsibility for target acquisition. Several factors are identified
that might affect the vigilant behavior of armor crews: psychophysical
variables (the modality, conspicuity and probability of signals, nonsignal
event rate, task complexity), environmental variables (noise, vibration), and
operator state (sleep loss, task-induced stress).
Although there is considerable literature on vigilance, very little infor-
mation is available on the effects of transitions on vigilance performance.
Studies to examine this varied event rate or dual task load to produce transi-
tions in workload. Evidence suggests that performance suffers following
transitions, relative to steady-state workload conditions. A number of gen
OCR for page 6
6
WORKLOAD TRANSITION
eral approaches for enhancing the quality of sustained attention in opera-
tional settings have been suggested, including reductions in signal uncer-
tainty, the moderation of environmental sources of stress, and training.
GEOGRAPHIC ORIENTATION
There is a strong similarity in factors related to geographic orientation
between tank crews and helicopter pilots, both of whom often operate in
environments in which there are no explicit visible or electronic routes to
follow. Local terrain features may obscure their view of significant land-
marks, making it difficult to relate local terrain features to a more global
context. Because electronic aids must have a line of site with the target and
tanks have few navigation instruments, helicopter and tank crews must cor-
relate features viewed in the external scene or described by other crew
members with those depicted on paper maps. This may require mental
transformations and rotations and accurate estimates of speed and distance
traveled to determined when a landmark should be visible and when choice
points have been reached or missed. The difficulty of maintaining geo-
graphic orientation depends on the availability and visibility of distinctive
landmarks, familiarity with the area, and the adequacy of maps, premission
planning, and crew coordination.
DECISION MAKING
Team decision making depends jointly on the decision-making capabili-
ties of the team leader and on information flow. Analysis of decision-
making studies reveals that shortcomings in decision making may result
from limitations in a number of the processes necessary to execute a deci-
sion, from initial information gathering to final choice. In order to be able
to make a good decision, one must have good situational awareness. Deci-
sion makers bring with them a number of biases and heuristics, including:
(1) salience bias- the tendency to focus on the most salient cue, rather than
that which may be most informative and diagnostic; (2) availability heuris-
tic the tendency to base one's actions on the hypothesis that is most avail-
able in memory; (3) anchoring heuristic the tendency to stay with a cur-
rent hypothesis and inadequately consider new information that might shift
one's beliefs in favor of a different hypothesis; and (4) confirmation bias-
the tendency to seek new information that supports one's currently held
hypothesis and to ignore or inadequately weigh information that may sup-
port an alternative hypothesis.
To counteract the limitations of human decision making, four general
remediation solutions have been proposed: computer-based decision aiding,
debias training, domain training, and development of team cohesion.
OCR for page 7
SUMMARY
7
STRATEGIC TASK MANAGEMENT
Strategic task management involves several components. One compo-
nent is the switching between tasks or between different strategies in per-
forming a task. Research in basic laboratory environments suggests that
this switching can be done rapidly and efficiently, and that differences be-
tween people in switching speed can predict differences in performance in
complex tasks such as driving or flying. The speed with which activities
can be initiated depends on expectancy and the degree of uncertainty of
possible alternative activities. Action can also be stopped rapidly, although
under high stress there may be a tendency to inhibit action stopping or
switching. That is, activities may persist longer than they should.
Another aspect of strategic task management is the management of task
priorities: addressing high-priority tasks before those of lower priority.
Effective management depends, in part, on good situation awareness: knowing
what tasks are currently in the queue that need to be done. Studies of task
priority management indicate that people are good but not perfect in manag-
ing tasks. Some aircraft accidents result from neglect of high-priority monitoring
tasks, such as monitoring altitude. When task demands change, people are
not always very good at rescheduling their activities, and there is a ten-
dency to procrastinate in performing some tasks. Preview of upcoming task
demands appears to improve task management skills.
TEAM LEADERSHIP AND CREW COORDINATION
Optimal team performance during a workload transition depends heavily
on effective crew resource management personnel within the team sharing
information effectively and coordinating their monitoring and task perfor-
mance responsibilities. A breakdown in leadership and coordination among
crew members may result in flawed decision making and improper actions.
The impact of automation on reduced crew complement and the role of
personality factors as determinants of crew performance are issues that need
to be further addressed.
Communications is another variable that impacts crew performance.
Standardizing and restricting vocabulary, presenting redundant information
(e.g., presenting the same information both visually and auditorially), and
sending many short messages rather than fewer long ones all foster good
communications by reducing the possibility of confusion or misinterpreta-
tion. Research indicates that effective crews exchange information and use
available resources better than noneffective ones.
Given that the crew leader bears ultimate responsibility for the crew's
performance and safety, he or she is the most important single component
of the crew. Two leader behavior patterns have been found to be the source
OCR for page 8
8
WORKLOAD TRANSITION
of poor crew performance: (1) autocratic behaviors that inhibit communica-
tion from subordinates and (2) failure to coordinate and guide actions of
crew members.
TRAINING FOR EMERGENCY RESPONSES
Given that the final design of the tank or any other system takes into
consideration all of the above factors, adequate training is essential to en-
sure effective performance, with acceptable levels of crew workload. Initial
training introduces crew members to the tasks they will perform and pro-
vides instruction and/or practice in conducting specific elements. Unit training
provides additional experience, places task components in context, and pro-
motes team skills. Extended practice enables parallel processing and the
development of alternative strategies and reduces the need for much con-
scious decision making evident early in practice. For example, psychomo-
tor skills progress from continuous, conscious error correction and compen-
sation to the execution of well-learned, automatic motor programs.
Training and experience facilitate the development of mental models
that enable the prediction of future states from present evidence and frees
operators from the need to monitor status displays continuously. Experts
are more likely to perceive task goals and performance criteria correctly,
thinking in terms of larger units of activity than novices. They complete
subtasks without conscious attention, recognize patterns of information, and
initiate action sequences with single decisions. They can use established
patterns of motor responses, efficient strategies, and exert timely and appro-
priate effort. Finally, experts are likely to notice and recover from their
own errors and system failures earlier and more easily than novices. All of
these differences between novice, or less capable, operators and expert, or
more capable, operators determine the workload cost of achieving the same
level of performance and may establish the maximum levels of performance
that can be achieved, regardless of the effort exerted. For example, if
routine tasks are performed automatically and correctly, additional resources
will be available to perform nonroutine tasks.
Training and specific skill acquisition extend an individual's capability
to handle workload; however, certain contributors to high workload, such as
the necessity to perceive faster, are not amenable to training. Many of these
factors are related to and limited by cognitive abilities of the individual.
The specific performance requirements for tank crews span the con-
tinuum from performance of complex, problem-solving tasks to routine,
procedural tasks. For example, the tank crew should be capable of perform-
ing certain tasks automatically, while the commander must possess the flex-
ible adaptability to apply multidimensional thinking and decision making
when appropriate. The training demands for these two are very different.
OCR for page 9
SUMMARY
9
To perform in an expert fashion under stress, commanders and crews
must have a thorough understanding of the system, should have automated
the lower-level procedural skills required to respond appropriately, and must
be able to respond to unique circumstances. The primary decision maker or
commander must have the opportunity to practice emergency problem solv-
ing and decision making, as well as routine proceduralized tasks. Practice
under realistic, challenging conditions will allow better use of mental re-
sources for the nonroutine elements of the emergency situation.
Three training approaches have particular relevance for the training of
crew members who may be required to respond to emergency situations:
simulation networking (SIMNET), embedded training, and crew resource
management (CRM) training. SIMNET allows individual crew members
through battalion commanders to practice tasks and roles in a realistic,
complex simulation environment necessary to develop the appropriate skills.
The technology of embedded training allows individuals to practice proce-
dural tasks in the operational environment. CRM training focuses on the
crew's management of resources and communications.
RECOMMENDATIONS FOR RESEARCH
in carrying out its charge, the panel identified existing research results
that could be applied and research that needs to be conducted to answer
important questions and inform operational policy. A large number of rec-
ommendations appear throughout the report, but those considered most im-
portant are identified below. Recommendations for research appear first,
followed by recommendations for the implementation of research results.
Research Recommendations
· The effects of such factors as speed-accuracy tradeoffs, task schedul-
ing, and task duration on operator performance under different levels of
workload are not well defined and need additional research.
· More research is needed on team workload management strategies
and their effectiveness, such as the effect of teammate cooperation on per-
formance.
· More research is needed to identify the joint effects of stress, fa-
tigue, training, crew coordination, and environmental stressors on operator
. . . . .
workload In transition situations.
· Quantitative scales to rate the attributes that can be placed on the
different workload drivers for the development of predictive workload mod-
els need to be developed.
· Continued research and development to validate global operator models
of human performance in complex systems are needed.
OCR for page 10
10
WORKLOAD TRANSITION
· The tradeoff between costs and benefits of automation needs to be
examined in this environment.
· Research should be conducted on the effects of stress on communi-
cation.
· Research is needed on the minimum nap time necessary to prevent or
mitigate performance degradations.
· Research is needed on the effects of team monitoring.
· More research regarding the effectiveness of debiasing needs to be
conducted.
· Additional research is needed to identify the speed, strengths, and
limitations of activity switching in high workload/high stress environments,
especially the extent and prevalence of cognitive tunnel vision.
· Research is needed to examine the impact of partially reliable pre-
v~ew.
· Research on task rescheduling according to an optimal prioritization
scheme needs to be conducted.
Research is needed to examine the factors that enhance crew com-
patibility and productivity as well as the individual characteristics that pre-
dict how an individual and team will function productively.
· Additional areas for consideration include assessment of the social-
psychological impact of automation and reduced crew complement and an
investigation of the role of personality factors as determinants of crew per-
formance.
.
· Research is needed on the impact of stress on task performance un-
der varying degrees and types of training.
· Research is needed for the validation of training approaches against
performance in a combat-like environment.
Application of Research Results
· Adequate training and preparation, adapting strategies and tactics
most appropriate for the situation, effective leadership, and smooth crew
coordination could counteract some of the detrimental effects of imposed
task demands.
· In order to better adapt to the transition situation, design solutions
and personal solutions need to be identified and employed. For example,
design solutions would include the following:
- using familiar elements and eliminating nonessential ones,
displaying information that is directly necessary,
highlighting information,
- integrating displays,
-making on-line emergency procedures brief and succinct, and
providing procedural instructions that are phrased as actions to be
taken, not as prohibited actions or system state descriptions.
OCR for page 11
SUMMARY
11
Personal solutions include the following:
preplanning, anticipating, and rehearsing actions to be taken un
der stress,
employing cognitive approaches to stress might be taken, i.e., providing
information, and
using team-building and environmental buffers to minimize com
munication problems.
.
To minimize some of the physical stress and discomfort:
-tighter, more comfortable headgear should be developed,
the displays and controls should be analyzed and rearranged.
4= ,
the placement and design of the radio equipment should be exam-
ined,
shock isolation, such as seat shock absorbers, and personal re-
straints should be used, and
temperature extremes should be eliminated.
· A duty schedule, with special attention to the cycle time, is essential
to good crew performance.
· Sleep periods should be mandated and enforced, especially for op-
erators who perform low-level vigilance monitoring tasks or complex cog
native tasks.
· Preemptive naps should be scheduled in a staggered manner across
time and crew members.
· Countermeasures for sleep loss (e.g., stimulants, increased physical
activity, naps, monetary incentives, diet, and increased social activity), which
are not effective after the second or third nights of continuous operations,
should not be used.
· A minimum level of comfort and darkness for sleep should be pro-
vided.
· Computer assistance would assist target detection, because human
monitors need adequate sleep.
· Designers should try to provide simultaneous-type displays for target
acquisition functions.
· Crews should be instructed on the biases and nonoptimal strategies
of their vigilance functions to optimize their response strategies.
· Crews should be trained with target cueing or with knowledge of
results in tasks requiring sustained attention.
· Crews should be provided with accurate, possibly electronic, naviga-
tional information.
· Navigational systems should support north-up (to facilitate mission
planning and communication between individuals who do not share the
same perspective) and track-up (to facilitate wayfinding, locating targets,
and communication between individuals who share same perspective) map
formats.
OCR for page 12
crew resource management training,
.
2
WORKLOAD TRANSITION
· Both planned route and current position should be displayed on the
maps.
· Design efforts must address the potential confusion of the source of
communications under high workload.
· Teams should maintain their integrity over some period of time.
· Crew composition, which has been found to affect performance, has
three possible solutions:
select out operators who have been found to inhibit the develop-
ment of effective communication, and
crew compositionJcreation.
In training, repetition is needed, and a greater variety of tasks need
to be practiced.
· Training to the point of automatic processing for proceduralized tasks
IS require .
· There should be maximum utilization of SIMNET.
· Emergency problem solving and decision-making management needs
to be practiced.
· Emergency problem solving must be trained first in a nonstressed
environment.
· Fault diagnosis must be taught in complex systems.
Representative terms from entire chapter:
sleep loss
