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4 Stress The battlefield environment is a stressful place and, as graphically de- scribed by Keegan (1976), those stresses are amplified within the armored vehicle. Indeed, the post-transition phase of any team situation will impose a substantial degree of stress, incorporating time pressure at a minimum, often augmented by danger, noise, and a host of other environmental stres- sors. The concept of stress as it influences human performance may be understood in the context of Figure 4.1. At the top of the figure are identi- fied a set of stressors; these are influences on information processing and cognition that are not inherent in the content of the information itself. Stressors may include features of the work environment like noise, vibration, heat, dim lighting, and high acceleration, as well as such psychological factors as anxiety, fatigue, and danger. Such stressors may have different manifesta- tions: subjective experience, physiological changes, and performance dec remeets. Stressors may affect a subjective experience. For example, individuals are usually (but not always) able to report a feeling of frustration, or arousal, as a consequence of a stressor. Closely linked, a change in physiology is often observable. This might be a short-term change- such as the influence on heart rate associated with the demands of flying as pilot-in-command (Hart and Hauser, 1987) or the stress of controlling air traffic in high-load situations (Romhert, 19799. Or it might be a more sustained effect, such as the change in the output of catecholamines, measured in the urine, after periods of simulated combat maneuvers flying in an F16 (Burton et al., 1977), inflight emergencies, or actual battlefield events (Bourne, 1971~. 94

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STRESS 95 The subjective and physiological characteristics are often, but not invar~antly, linked. The subjective experience of stress may also mediate performance. For example, one who does not realize the risk or danger of a particular situation will experience less stress than one who does a subjective ap- praisal of the situation, thereby mediating stress effects on performance (Coyne and Lazarus, 1980J. As Figure 4.1 shows, the effects may be either direct or indirect. Direct effects are stressors that influence the quality of information perceived by the human operator or the precision of the motor response. For example, vibration will reduce the quality of visual input (as well as the quality of motor output), and noise will do the same for auditory input. Time stress may simply curtail the amount of information that can be perceived, in a way that will quite naturally degrade performance. Direct effects also in- clude the effects of noise on working memory (Poulton, 1976~; rehearsal of a set of instructions or coordinates, for example, will be more difficult in noise. Direct effects can also include the distraction experienced by an operator who is concerned about personal problems or danger, who may therefore redirect attention to thinking about those problems, rather than to the job at hand. Some direct-effect stressors (e.g., noise or vibration) as well as others for which no direct effect can be observed (e.g., anxiety or fear) also influ- ence the efficiency of information processing. In this chapter we first con- sider stressors that are characteristic of the physical work environment in which the tank crew operates, described in Chapter 1. We then address what is known about the effects of psychological stress on performance Direct. . . E.g., lighting, noise, heat, vibration INPUT STRESSORS ' Indirect... `` E.g., anxiety, ~ fear, fatigue 1, INFORMATION PROCESSING FIGURE 4.1 Influence of stress on human performance. Direct... E.g., heat, vibration ~ , ~ BEHAVIOR

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96 WORKLOAD TRANSITION under conditions of high anxiety and arousal. Finally, we consider stress in the context of team performance, examining the characteristics of teams that make them more stress resistant. The discussion emphasizes to a greater extent the stress effects present in the post-transition period. In Chapter 5 we consider the most potent stressors of the pretransition period: sleep loss and fatigue and their influence on both pre- and post-transition performance. STRESS IN THE WORK ENVIRONMENT The term work environment encompasses all the variables that deter- mine the physical comfort level of users. These include ambient tempera- ture, relative humidity, atmospheric pressure, airflow, the presence or ab- sence of noxious fumes or toxic substances, motion, acceleration (normally expressed as G-loading), and ambient sound and light levels. For most of these parameters there exist absolute limits within which humans can func- tion and beyond which they cannot function or, for some variables, even survive. There are, in general, much narrower limits within which humans feel comfortable. An example of such a comfort zone is contained in the American Society of Heating, Refrigerating, and Air-Conditioning Engi- neers (ASHRAE) comfort standard (American Society of Heating, Refriger- ating, and Air-Conditioning Engineers, 1985~. The definitive military hu- man factors standard, MIL-STD-1472C (U.S. Department of Defense, 1981), specifies such zones for several environmental variables. The degree to which comfort enhances performance is a function of the nature of the tasks that must be completed. The differential effects of many environmental factors have been demonstrated on the performance and physical workload of various types of tasks. There are well-known relationships between certain environmental variables, such as ambient temperature and relative humidity and the ability to do physical work (Occupational Safety and Health Administration, 1974~. Among the factors known to increase workload or, more accurately, to decrease performance are high levels of ambient noise (Davies and Jones, 1982), high temperature and humidity (Hancock, 1981), low temperature (Enander, 1984), and motion and vibra- tion (International Organization for Standardization, 1978~. Obviously, high levels of toxic materials in the environment can have a substantial impact on the user's ability to perform tasks. The tank environment combines some of the most potent factors that have been shown to adversely affect performance. Even in a nonchemical/ biological-warfare (non-CBW) battlefield scenario, tank crew members are subjected to elevated temperature and humidity due to the fact that tanks are not air conditioned. Heat casualties are quite common during training in field exercises. It is also common for the interior of the tank to be filled with noxious fumes from leaking hydraulic fluid and spent propellant from

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STRESS 97 ordnance. When buttoned up, the interior of the tank is pressurized by an air movement system that brings outside air in through filters that remove particulate and some chemical components. This air is not conditioned for temperature or humidity. In the COW battlefield environment, these condi- tions are exacerbated by the requirements of wearing environmentally pro- tective clothing or "MOPP gear" and remaining buttoned up inside the tank for long periods of time. Even in non-CBW environments, all crew members must wear helmets with integral earphones and a movable microphone. The purpose of these helmets is not so much to protect crew members from external ordnance as it is to protect them from head injuries caused by hitting the interior surface of the tank while it is moving over terrain. The large, fully enclosing earphones insulate the crew members from noise generated by the tank running gear. The helmet allows crew members to communicate with each other and with other tanks in their platoon. Unfortunately, the helmets are heavy and tend to trap heat. The earpieces press against the sides of the head causing discomfort after even short periods of time. It is reasonable to infer that environmentally extreme conditions will affect some tasks more than others. Some tank crew positions are primarily physically oriented, i.e., those of loader and driver, whereas others are con- cerned mainly with cognitive tasks, i.e., those of gunner and tank com- mander. However, even those crew positions that are physically oriented have task responsibilities that require mental sharpness. Specifically, all crew members are expected to search for threats and targets. During opera- tions of long duration, the crew is put on a sleep-wake cycle that requires all crew members to assume the responsibility of searching for enemy threats. The result of this division of responsibilities is that adverse environmental factors are likely to increase the workload of all tank crew members and, consequently, decrease the performance of the tank crew as a whole. Long-duration operations also bring into play another environmental factor that should be noted. Tanks contain no toilet facilities. When but- toned-up, crew members are not allowed to leave the confines of the tank. The unpleasant, but inevitable result of these restrictions is that all bodily functions must be accommodated within the tank. It is probably an under- statement to observe that such a situation can lead to an environment that is not conducive to superior task performance. STRESS AND HUMAN PERFORMANCE Many aspects of the relation between stress and performance are related to the construct of arousal. The relation between stress-induced arousal and performance has sometimes been described in terms of an inverted U-shaped function, as shown in Figure 4.2. With increasing arousal, performance

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98 Optimum Level of Arousal o a) // // WORKLOAD TRANSITION Simple Task \ \~ OCR for page 94
STRESS 99 cognitive effort or resources mobilized for task performance. In contrast, the downward limb is the consequence of a more specific effect of high arousal on the selectivity of attention, which causes the operator to focus on a more restricted set of environmental or internal sources of information. An appropriate metaphor is to say that high levels of stress narrow the spotlight of attention. Extending this argument logically leads to the conclusion that high arousal should be more detrimental to tasks that require the processing of several information sources (i.e., complex tasks) than to tasks which depend on only a few cues (i.e., executing a well-practiced skill). This difference in arousal effects resulting from task complexity is depicted by the differ- ences between the two curves in Figure 4.2. The optimum level of arousal for the simple (or the more highly practiced) task is higher than for the complex task. A relevant example of the different effects of stress on performance as a function of complexity is an experiment carried out by Berkun (1964~. Using Army soldiers engaged in simulated (but highly realistic) tasks, Berkun employed three different experimental manipulations to induce a very real- istic experience of stress. In one manipulation, subjects were led to believe that the aircraft in which they were flying was in danger of crashing as they attempted to fill out an insurance form. In a second manipulation imposed during combat exercises, subjects were led to believe that artillery shells were exploding around them as a result of a confusion about their location, as they tried to follow procedures to initiate a radio call to redirect the fire. In the third manipulation, subjects believed that a demolition that they had initiated had accidentally caused a serious injury to one of their fellow soldiers, and they were now required to call for medical assistance. Thus, in all cases, subjects were deceived to believe that they, or someone for whom they felt responsible, were at serious mortal risk. Berkun found that in all three cases, the high level of stress and arousal induced by the anxiety or perceived danger led to degraded performance on following the necessary procedures. However, this degradation was less for soldiers with greater experience. This last finding may be placed nicely into the context of Figure 4.2, if it is assumed that the more skilled soldier faces a less complex task in problem solving. Much of the perceptual and short-term memory requirements of task solution are replaced by direct recall from long-term memory. The increased arousal caused by stress then exerts a less degrading effect. While Berkun's study clearly illustrates the loss of performance under stress, it is less illuminating regarding the qualitative manner in which per- formance is affected. This issue of qualitative stress effects will now be addressed in more detail.

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100 WORKLOAD TRANSITION QUALITATIVE PATTERN OF STRESS EFFECTS Hockey (1984, 1986) expanded on the two factors (arousal and tunnel- ing) that underlie the Yerkes-Dodson law and has attempted to identify more subtle patterns of stress effects on performance. Reviewing a large number of studies that examined the effects of stress on human perfor- mance, Hockey distilled the pattern of stress effects into the form shown in Table 4.1. Each stressor appears to be identified by a profile or signature of effects across a set of five critical information processing components: general arousal, selectivity of attention, speed and accuracy of performance, and capacity of short-term memory (working memory). The focus in this section is on a stressor that is an important character- istic of many operational environments in the team transition situation: the anxiety, fear, or arousal associated with failures of task performance or dangerous' threatening environments (Idzikowski and Baddeley, 1983a, 1983b). This fear is often coupled with a shortage of time to deal with the crisis. (The direct effects of time pressure on performance were discussed in some detail in Chapter 3.) This stressor may characterize the experiences of the flight crew, following an engine stall in midair in which both danger and time stress are imposed; the nuclear control room personnel, following ini- tial alerting of a failure; or the tank crew moving into combat. Idzikowski and Baddeley (1983a, 1983b) present a review of research and case study findings related to this form of stress; the reader can refer to treatments by Hamilton and Warburton (1984), Broadbent (1971), and Hockey (1986) for broader discussions of stress. In the following review of research, we also capitalize on the psychological equivalence of signature patterns between noise and anxiety as shown in the table, allowing us to extrapolate from the effects of noise to those of danger-producing anxiety. It is reasonable, also, to assume that in the noisy and dangerous environment of the tank, these two effects would be additive. In the following discussion, we use the term stress to refer to the combined effects of danger, anxiety, and noise. Within the framework of teams in transition addressed in this report, the transition effects involve a rapid jump from the left to the right side of the Yerkes- Dodson curve. Our focus in Chapter 5 is on the left side of the curve. Here we address performance effects on the right or high end. Attentional Tunneling Weltman et al. (1971) compared the performance of two groups of divers on a central and peripheral signal detection task. One group was led to believe it was under conditions of a 60 foot dive in a pressure chamber; the other was not. In fact, there was no change in pressure for either group. Both groups showed similar performance on the central task, but perfor

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STRESS TABLE 4.1 The Patterning of Stress Effects Across Different Performance Indicators. 101 Performance Indicators Speeded Responding GA SEL S A STM Sources/Reviews Noise Anxiety Incentive Stimulant drugs + Later time of day Heat Alcohol Depressant drugs Fatigue Sleep loss Earlier time of day + + O. - + + O - + + + + + + + O - + _ _ + O + O - O _ O o + + 2,3,4,5,7,8 4,12 2,4,5 2,4,13 1,2,4,5,6,8 2,4,11 2,4,7,8,13 2,4,10,13 2,4,9 2,4,5,7,8 1,2,4,5,6,8 The table summarizes the typical outcome in various studies using these stress variables in terms of their effect on the five behavioral indicators show: GA general alertness/activation (subjective or physiological arousal); SEL - selectivity of attention; S and A refer to overall speed and accuracy measures in speeded responding tasks; STM short-term memory. A plus (+) indicates a general increase in this measure, a zero either no change or no consistent trend across studies, and a minus (-) a general tendency for a reduction in the level of the indicator. A question mark is used to indicate cells where there is insufficient data. Sources of data: (1) Blake (1967a, 1971); (2) Broadbent (1971); (3) Broadbent (1978); (4) Davies & Parasuraman (1982); (5) M.W. Eysenck (1982); (6) Folkard (1983); (7) Hamilton, Hockey, & Rejman (1977); (8) Hockey (1979); (9) Holding (1983); (10) Johnson and Chernik (1982); (11) Ramsey (1983); (12) Wachtel (1967, 1968); (13) Wesnes and Warburton (1983). SOURCE: G.R.J. Hockey, "Changes in Operator Efficiency as a Function of Stress, Fatigue, and Circadian Rhythms." P. 44-39 in K.R. Boff, L. Kaufman, and J.P. Thomas (eds.), Hand- book of Perception and Human Performance. Chichester, England: John Wiley and Sons, 1986. Reprinted by permission. mance on the peripheral task was significantly degraded for the pressure group. This group also showed greater anxiety-related increases in heart rate, substantiating the increased level of stress. Stress may also cause a focusing of attention on one particular task or cognitive activity, as well as on a particular perceptual channel. In the analysis of cockpit voice record- ings at times of high stress prior to accidents, Helmreich has found evi- dence of severe breakdowns in the pilots' ability to handle multiple tasks or multiple concerns. Although perceptual or cognitive tunneling produced by stress usually degrades performance, it is also possible to envision circumstances in which this tunneling may actually facilitate performance, in which focused atten

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102 WORKLOAD TRANSITION lion on critical task aspects is desired. Indeed, this positive effect was observed in a study by Houston (1969), who found that noise stress im- proved the focus of attention on the relevant aspect of a stimulus and re- duced the distracting effect of irrelevant aspects. Data provided by Houston's experiment and others suggest that the attentional or cognitive tunneling resulting from stress is defined in terms of subjective importance or priority. That is, performance of those tasks or processing of that information thought to be most important remains unaf- fected or perhaps is enhanced (through arousal), while processing informa- tion with lower perceived priority is filtered (Bacon, 1974; Broadbent, 1971~. In one sense, this kind of tunneling is optimal, but it will produce undesir- able effects if the subjective importance that defines the attended channel proves to be unwarranted. Such was the case, for example, in the incident of the Three Mile Island nuclear power plant (Rubinstein and Mason, 1979~. Immediately after the crisis in the plant developed and under the high stress caused by the initial failure, the operators appeared to be fixated on a single faulty indicator, supporting an incorrect belief that the water level in the reactor was too high, thereby preventing their attention from focusing on more reliable indicators that supported the opposite (and correct) hypoth- esis. As suggested by this example and elaborated below, this narrowing effect can be directly related to biases in decision making. But for the operator who has a well-structured and accurate model of task demands and a well-developed skill in discriminating sources of useful (versus trivial) information, it can be expected that stress should lead to little degradation of performance, as reflected by the behavior of the United Airlines flight 232 crew (Predmore, 1991~. Working Memory Loss Mandler (1979) has discussed the degrading effects of anxiety on work- ing memory. Correspondingly, many of the difficulties in following proce- dures that Berkun (1964) observed when his Army subjects were placed under the stress of perceived danger can also be attributed to reduced work- ing memory capacity. Logie and Baddeley (1983) and Lewis and Baddeley (1981) have noted similar working memory decrements of divers perform- ing at depth. Idzikowski and Baddeley (1983a, 1983b) observed an anxiety- related working memory loss of speakers waiting in the wings to give their first public speech. Noise, as well as danger and anxiety, has also produced consistent effects on working memory (Hockey, 1986~. While it is intu- itively evident that the presence of noise would disrupt the ability to re- hearse verbal information in working memory (Poulton, 1976), it appears also that the combined stress effects of noise and anxiety may disrupt spa- tial working memory systems as well (Stokes et al., 1990; Stokes and Raby,

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STRESS 103 1989~. Indeed, in a simulation study of pilot decision making, Wickens et al. (1988) observed that the effects of noise stress were greatest on decision problems that relied on spatial visualization for their successful resolution. Communications Successful communications depend heavily on working memory, to re- member what has just been said. Hence, it is not surprising that communi- cations have sometimes broken down under conditions of stress. Analyses of crew communications in accidents in which a prolonged inflight emer- gency preceded ultimate disaster provide compelling evidence of the com- munication breakdowns that occur under conditions of extreme threat. These include fragmented communications, failures to process the information com- municated, and inability to deal with multiple tasks or concerns (Predmore, 1991). Long-Term Memory While stress appears to disrupt working memory, it appears to have less of an effect on the retrieval of information from long-term memory, to the extent that information is well rehearsed and memorized. For example, in their study of pilot judgment, Wickens et al. (1988) found that those judg- ments requiring direct retrieval of facts from long-term memory were rela- tively unimpaired by stress. The differences in Berkun's findings between more and less skilled soldiers is also consistent with this view. Stokes et al. (1990) found that the decision-making performance of novice pilots deteriorated under stress, whereas performance of a group of highly trained pilots in the same circumstances was not affected. Presumably the latter group was more able to rely on direct retrieval of information from long-term memory in making their deci- sions. Similar to the narrowing effect that stress exerts on perception and selective attention, however, stress appears to restrict the information re- trieved from long-term memory more specifically to those habits that are well learned or overlearned (Eysenck, 1976~. Although there do not appear to be much experimental data supporting this claim, at least one study shows that increased stress actually eliminates some of the benefits of ex- pertise and training in decision making (Ben Zur and Breznitz, 1981~. Studies by Fitts and Seeger (1953) and Fuchs (1962) and analyses of aircraft acci- dents carried out by Allnutt (1987) have all suggested that stress will lead to a regression to earlier learned and more compatible response patterns, when these patterns may conflict with incompatible (but appropriate) ones. Col- lectively, these findings suggest the importance of extensive training in

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104 WORKLOAD TRANSITION procedures and actions that may need to be taken in emergency. They further emphasize that such procedures should require only actions of high compatibility. The findings, however, emphasize the extent to which cre- ative innovative problem solving may be degraded under stress since, by definition, such problem solving will not have been accomplished in the same way in the past and hence repetitive practice of the same steps cannot be achieved. Strategic Shifts There is some evidence from behavioral studies that stress leads to consistent shifts in processing strategy. In the study of the anxiety brought on by the first parachute jump, for example, Simonov et al. (1977) observed a shift in detection performance that can be characterized by a riskier crite- rion setting. The paratroopers were simply more likely to respond "yes" and hence made more hits and more false alarms. Hockey (1986) concludes that there is a general effect of noise and/or anxiety stress on the speed- accuracy tradeoff, shifting performance to a less accurate but not slower level. In their study of pilot judgment, Wickens et al. (1988) found that judgments were less accurate but not necessarily slower under the combined stress effects of noise, time pressure, and threat of loss of income. The tendency of those under the stress of an emergency to shift perfor- mance from accurate to fast (but error prone) responding has been cited as a concern in operator response to complex failures in nuclear power control rooms. The operator often has a desire to do something rapidly, when in fact this impatience is often counterproductive until the nature of the failure is well understood. In the Three Mile Island incident the hasty action of the control room operators was to shut down an automated device that had in fact been properly doing its job. Decision Making Understanding the effects of stress on decision making has always been of great interest to the human factors profession. The importance of this knowledge has been enhanced by the analysis of the faulty decisions made in the Three Mile Island incident and, more recently, by concerns over the decisions made in the U.S.S. Vincennes incident (U.S. Navy, 1988; see also Chapter 81. Both of these incidents are particularly relevant to the focus of this report because of the involvement of teams of operators in making decisions following a fairly abrupt transition of system state, under a high level of stress. The concern that decisions degrade under stress is rein- forced by anecdotes and case studies of poor pilot judgments that have occurred under stressful conditions of bad weather, spatial disorientation, or

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STRESS 111 jumps, signaling the relief, as it were, that successful performance was possible. In this regard, it is not surprising that, in a wide variety of contexts, research findings demonstrate the efficacy of prestress training, geared at providing preparatory information in order to reduce the novelty of the stressful situation. Novelty, as Rose (1987) and others have indi- cated, is a primary component of the intensity of the stress response: the greater the novelty, the greater the intensity of the stress experienced in many settings. Thus, training should be a crucial component of any pro- gram to enable tank crews to manage stressful environments. Finally, there appears to be considerable merit in training that makes crews aware of the potentially degrading effects of stress. Survey data collected from civilian and military flight crews using the Cockpit Manage- ment Attitudes Questionnaire (CMAQ) contain items aimed at determining attitudes regarding personal awareness of the effects of external stressors on human performance. In particular, a Recognition of Stressor Effects subscale of the CMAQ measures perceptions of personal capabilities when faced with stressful conditions and the ability to put aside stresses caused by personal problems when faced with the need to perform at high efficiency. One of the striking findings from the survey data is how little awareness flight crews have of the deleterious effects of stress on individual and group performance (Helmreich, 1984~. The model pilot tends to endorse a posi- tion reflecting an ability to leave behind personal problems and a perception that personal performance is unaffected by life-threatening, emergency con- ditions. Such attitudes represent the classic model of the "white scarf,' aviator. TEAM MODELS: IMPLICATIONS FOR STRESS MANAGEMENT The bulk of the research on stress addresses individual-level responses (physiological, psychological, and behavioral) often in laboratory settings removed from the more complex contexts in which multiple stressors usu- ally occur. Prevention and intervention programs are also often addressed as individual-level strategies for reducing negative stress-related consequences (e.g., therapy, exercise, training programs). Fewer studies examine the group and organizational level structures and processes that might be modified in order to diminish the problems created for individuals enduring a high level of stress in the workplace. A simple example is the case with air traffic controllers. Studies typically focus on the effects of the stress of their jobs on their own responses, physiological and psychological (as well as on their families). As Matteson (1987) suggests, stress may often be relieved, not by training particular individuals in how to cope with stress, but by altering the conditions that create the negative stress responses. Human and organi- zational resources can be used, for example, to hire more controllers to

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2 WORKLOAD TRANSITION handle peak times and high volumes of traffic Kahn (1987) concludes a recent review of stress research indicating optimism about the potential for organizational-level interventions. While research findings concerning the responses of individuals in vari- ous occupations to stressful situations or encounters are important, perhaps even more useful for the investigation of teams in transitions, such as tank crew operations in stressful environments, are the studies of teams and team-building strategies. Numerof (1987) and S. alas and coworkers (Baker and Salas, 1992; Driskell and Salas, 1992; Tannenbaum et al., 1992) pro- vide models of team characteristics that may be relevant to teams in a workload transition. Teams are defined by Numerof as groups that have a high level of energy directed toward accomplishing a goal, usually in set- tings in which the tasks to be performed require multiple inputs and cannot be handled by any individual alone, which is generally true of tank crews during periods of engagement. Effective teams are referred to as groups that have a combination of high loyalty, morale, commitment, adaptability, and exchange and coordinate information. These good team qualities, which may provide a buffer against organizational stress, include: effective lead- ership, appropriate selection of members, commitment and cohesion, open climate, achievement motivation, effective work methods, clarity of proce- dures, giving and acceptance of constructive criticism, individual initiative, high creativity, positive intergroup relations, and role clarity. These characteristics are briefly described below, based on Numerof's (1987) review. Various studies support the significance of the individual components of the model, but what remains to be specified is the relative impact of each component on team performance and the optimal mix. Ef- fective leadership is viewed as one of the most important components, given the wealth of research on this factor (see Chapter 10~. What appears to be critical is the ability of the leader to change leadership style based on the requirements of the situation and to integrate the needs and individual abili- ties of the team members to meet the demands of the task situation. We will expand on our discussion of this factor subsequently, given its significance for team performance. Appropriate selection of members refers to the extent to which the individuals are well matched as a team to the task requirements. This includes the match between each individual and the job requirements, or what is referred to above as the job-person fit. This issue is discussed in greater detail in Chapter 10 in the context of airline crews, on which there has been a great deal of research involving the task and social skills re- quired to maximize crew performance ire the cockpit in particular, to opti- mize crew performance and decision-making skills under the high stress produced by emergency situations. Commitment and group cohesion are referred to frequently in the litera

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STRESS 113 lure on group productivity and effective teams. The usual assumption is that high levels of cohesion and commitment enhance group productivity. While this is generally true (see review by Ridgeway, 1983), high cohesion may also result in lower group productivity if the performance noes of the group run counter to those of the overall organization (e.g., the normative pressures in some work groups that limit work output or the rate of produc- tion). Furthermore, highly cohesive groups may also be subject to the problem identified by Janis (1972) as groupthink, situations in which group members who offer information or criticisms that deviate from the more popular decision in the group are ignored. According to Ridgeway (1983), this high level of cohesiveness may cause groups to make poorer decisions than they otherwise might. And yet highly cohesive groups often have more trust in each other and coordinate their behavior more. It has been found (Kelley et al., 1965) that outside stress makes it harder for members to trust one another and coordinate their behavior together, which greatly increases the social difficulty of the group's task, although some evidence provided by Driskell and Salas (1991) suggests that this may not invariably be true. Therefore, more cohesive groups whose members have good interpersonal relationships should perform better under high stress conditions (Shils and Janowitz, 1948~. Many of the remaining team components are self-evident; thus, only those that are less so are discussed. An open climate is critical because it represents a team that has open direct communication and trust. In such groups members often feel at ease in taking what they consider appropriate risks, which in turn enhances opportunities for innovation and creativity. Achievement motivation refers to the extent to which team members are motivated toward performance goals and are willing to use feedback mechanisms to improve performance over time. Individual initiative is also an important component in effective teams since members are encouraged to emphasize their own unique contributions and to raise constructive ques- tions concerning procedures or suggestions and actions of other group members. Risk-taking is also encouraged, as is creativity. These factors may be less important during routine activity for tank crews, but they may be crucial during the transition phase and periods of high stress. The significance of cohesion, described above, arises in the context of team-building activities since teams may become isolated and more oriented to the enhancement of group performance, at the expense of other teams or units. For tank crew teams this is essential because of the interunit commu- nication and coordination required for successful maneuvers. Positive in- tergroup relations and corporate role clarity are critical for this reason. The former refers to the nature of the working relations with other teams or units, the latter to a clear picture of the way in which each team fits into a larger whole. Training could enhance both of these factors through simula

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4 WORKLOAD TRANSITION lion exercises and team-building strategies that increase cohesion without increasing intergroup competition. Often intergroup competition is used to enhance group cohesion, which would be counterproductive for the situa- tion in which intergroup cooperation is required, as in the transition phase and during subsequent maneuvers. However, to the extent that team building is useful to improve perfor- mance, raise levels of trust and commitment, and reduce stress that results from external factors as well as internal factors such as poor integration, lack of goal clarity, low levels of participation, and commitment, then strong leadership is required to counteract the stress created by a more open cli- mate involving more feedback and open management of conflict. Thus, we return to the importance of leadership. Good team qualities provide a buffer against stress, organizational as well as environmental. Trust, participation in decision making relevant to the work being performed, excellent communications, and a commitment to collaboration have all been identified as conducive to effective team-build- ing processes (Numerof, 1987; Tannenbaum et al., 1992~. Organizational resistance to effective team building comes from two sources, perceived threat and resistance to change. While some of these characteristics are not particularly relevant to the tank crew environment, other features are of central importance given that tank crews fit the above definition of a team (i.e., a group that requires coordination and cooperation to produce an out- come that no individual alone can produce). Various organizational effects resulting from the failure to implement good team-building strategies for both group and organizational-level out- comes have also been identified (Numerof, 1987~. For example, suboptimization occurs when organizational objectives are not clearly communicated. Indi- viduals may perform their own functions appropriately, but coordination is lacking. Organizational objectives may not be clearly defined or may change often and thus result in greater stress and uncertainty. If there is low commitment to the group and/or the organization and low cohesion, stress in the group will be high and team performance will be impaired. In orga- nizations in which work is characterized by high levels of interdependence, frequent problem-solving efforts, and high demands for accuracy and/or timeliness, team building is very important (Numerof, 1987~. For tank crews and, similarly, air crews, this model has implications for selection, recruitment, training, and the organization of roles and work assignments. In addition to environmental buffers (e.g., alterations in the actual tank environment), team-building efforts can be employed to minimize commu- nication problems and the stress-related inefficiencies in decision-making and problem-solving tasks, described in later chapters.

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