Below is the uncorrected machine-read text of this chapter, intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text of each book. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.
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
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
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
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.
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
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.
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
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.
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.
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.
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.
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.