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Stress and Performance
Pages 2-46

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From page 2...
... Within the context of this report, we shall attempt to use one set of operational definitions to define stress, and at least to be consistent with our own definitions of the primary psychological variables that induce many of the profound long-term effects commonly attributed to stress. Stress can be approached from a purely behavioral perspective, and it effects studies on primarily behavioral outcomes.
From page 3...
... Problems with this view have occurred at several levels. First, there was an early emphasis on the physical and chemical aspects of the stressful stimuli, and we now know that psychosocial stimuli are also potent elicitors of the stress response.
From page 4...
... We believe that much of the controversy over stress theory can be eliminated through clarification of the Different limb,. that is, by focusing on the nature of the stimuli that provoke physiological responses rather than on the physiological responses themselves.
From page 5...
... Utilizing a traditional measure of that period, the decline in eosinophils following stress, they found that eosinophils in the crew members were markedly lower 4 hours after the race. This decline could have been attributed solely to the exercise and physical strain, but the investigators also discovered that the coxswains and coaches had similar eosinophil drops, even though their stress was purely psychological.
From page 6...
... There is abundant evidence indicating that the hormone function of ocher endocrine systems -- including insulin, growth hormone, and prolactin -- can also be influenced by psychological variables. In addition, it has been demonstrated recently that the endorphins are also extremely responsive to stress.
From page 7...
... . That rapid hemorrhaging induces adrenocortical activity, while slow rates of hemorrhaging do not, once again indicates that the rate of stimulus change is one important parameter for the induction of pituitary-adrenal activity.
From page 8...
... To a large extent, the cognitive processes of comparison can be best understood by adding the concept of uncertainty, although there are some differences between uncertainty and novelty. Uncertainty seems to be a major factor underlying many psychological responses.
From page 9...
... . Thus, the habituated organism has an internal representation of prior events with which to deal with the environment -- expectancies -- and if the environment does not contain any new contingencies, the habituated organism no longer responds with the physiological responses related to the alerting reaction.
From page 10...
... Thus, minor changes, such as placing the animal in a different cage, but one identical with its home cage, resulted in an elevation of plasma corticosterone, but one that was significantly less than when the animal was placed in a totally novel cage containing none of the elements of its familiar living conditions. This capacity to make fine discriminations resulting in graded elevations of pituitary-adrenal activity are clearly demonstrative of the remarkable capacity of the central nervous system to regulate the output of pituitary-adrenal response.
From page 11...
... The adrenocortical response observed on subsequent testing of these animals clearly indicated the importance of reducing uncertainty by predictability. Animals that did not have the signal preceding the shock showed
From page 12...
... than do control animals. Thus, an organism exposed to an uncontrollable and unpredictable set of aversive stimuli not only shows a dramatic increase in adrenocortical activity while exposed to these conditions, but there is also a long-term effect in other unrelated test conditions.
From page 13...
... Thus, not only is an elevation of plasma corticosterone observed when reinforcement is eliminated, but if the animal receives less reinforcement than it has previously become accustomed to, then elevations of plasma corticosterone also occur. A similar phenomenon can be observed when using aversive stimuli.
From page 14...
... In the case of habituation, it is presumed that the organism has changed its evaluation of the stimulus through repeated experience and has developed a set of expectancies concerning the benign characteristics of the stimulus or environment. Coping, on the other hand, is a more active process and can be defined in terms of the absence of a physiological response even under conditions in which the aversive stimulus continues to be present.
From page 15...
... These responses are frequently effective in allowing the animal to avoid or escape from the stimulus, but they may also function by providing the animal with the opportunity to change from one set of stimulus conditions to another, rather than to escape the aversive stimulus entirely. Control, in and of itself, can reduce an organism's physiological response to such noxious stimuli as electric shock.
From page 16...
... A comparable group of monkeys were given the identical amount of noise, but were not permitted to regulate the duration. The animals that were allowed control procedures showed identical levels of plasma cortisol as those which were not exposed to the noise at all, compared to the yoked controls that showed extremely high levels of plasma cortisol.
From page 17...
... investigated a variety of endocrine parameters, including growth hormone and cortisol, in a large group of air traffic controllers during and after the work day. The job demands placed upon air traffic controllers have been considered to be extremely stressful.
From page 18...
... In an extensive series of studies, Weiss demonstrated that if two groups of rats were subjected to the same amount of electric shock, the severity of the ulceration was reduced if the animal could respond -- avoid and escape -- and if the situation had some feedback information, i.e., a signal following the termination of shock. Although feedback information usually occurs in the
From page 19...
... After the first jump experience, there was a dramatic elevation of plasma cortisol, but as early as the second jump, there was a significant drop to basal levels; thereafter, basal levels persisted on subsequent jumps. It is also important to note that the fear ratings changed dramatically following the first and second jumps, so that there was very little fear expressed after the second jump, even though there had been a very high rating of fear prior to the first jump.
From page 20...
... When one closely examines the three factors -- control, predictability, and feedback -- that have been shown to be involved in the coping process, they all have common elements which can be viewed within the framework of the determinant of the stress response proposed earlier -- uncertainty. Each of these factors, either acting alone or more probably in concert, appear to have the capacity to reduce uncertainty.
From page 21...
... measured urinary levels of corticoids in helicopter medics who were involved in medical evacuation flights. The striking finding was that when 17-OHCS levels on flight days were compared to output on those days when the medics remained on base, there were no significant differences.
From page 22...
... Their behavior and attitude was in sharp contrast to the captain and the radio operator, who spent much of their time communicating with the commanding officer at battalion headquarters, the captain under considerable pressure to perform well. Both the radio operator and the captain showed sharp increases in corticoid excretion on the day of the expected attack, compared to the days preceding and following this day.
From page 23...
... Although Bourne implicated social variables in the modulation of the adrenocortical response under these extremely stressful conditions, it is clear that the data are open to other interpretations. One could argue that in the case of both the helicopter medics and the enlisted men, they were able to exercise a large degree of control, and that this control may be the more important determinant of their low level of adrenal activity under these circumstances.
From page 24...
... . In order to determine whether a group could serve as an effective modulator of stress responses, we exposed squirrel monkeys to a live boa constrictor, which was presented above their cage in a wire mesh box.
From page 25...
... In 8 further study, social buffering, the apparent capacity of group membership to reduce adrenocortical responses to stress, was investigated in squirrel monkeys using a conditioning paradigm which involved classical conditioning or cortisol secretion. Adult males were assigned to two groups: one group received pairing of conditioned stimulus (CS)
From page 26...
... Animals housed in a group did not show the cortisol response elicited when individually housed. These results are consistent with the findings discussed above that the presence of familiar conspecifics can ameliorate a neuroendocrine response to psychological stress (Stanton et al., 198S)
From page 27...
... We have demonstrated in several experiments that there is a a striking elevation of plasma cortisol when animals are placed in a new social group and, in fact, this elevation of cortisol can continue for several months (Coe et al., 1983a; Gonzalez et al., 1981~. CATECHOIAMINES Thus far, we have emphasized the importance of psychological factors in regulating one of the major stress responses to the pituitary-adrenal system.
From page 28...
... Based on this experiment, catecholamines and plasma corticosterone appear to reflect, with only a minor difference, similar response characteristics to the presence of footshock. However, there are several studies indicating that the pituitary-adrenal response and the catecholamine response are indeed very different.
From page 29...
... previously reported that the ACTH response in animals that were shocked and fought, compared with those only shocked, was significantly reduced in the fighting animals. Dantzer and Mormede report that plasma corticosterone was also significantly reduced in animals tested after a repeated series of electric shocks when fighting was permitted.
From page 30...
... However, when the subject is given repeated experiences in which feedback information is presented and coping mechanisms are evoked, the response of the pituitary-adrenal system either diminishes or ceases. In contrast, it is assumed that these systems still require some attention and vigilance on the part of the subject, and therefore the catechol~mine system continues to be responsive.
From page 31...
... In this section, we will attempt to review the effects upon subsequent learning and performance proactive effects. which have been pursued within the context of testing learned helplessness theory.
From page 32...
... The dogs received 64 5 - second electric shocks of moderately high intensity delivered on the average of 1/minute. After 24 hours the animals were then placed in a standard two-way shuttle-box apparatus (designed to test conditioned avoidance learning)
From page 33...
... This is clearly relevant to the human performance field, where most of the stressful events would indeed not be restricted to the laboratory model of stress-shock. An example of the substitutability of uncontrollable aversive events on performance under different aversive conditions was provided by Altenor et al.
From page 34...
... has reported an experiment which demonstrates the aversive-appetitive interaction. In two experiments, prior exposure of rats to inescapable shock interfered with the subsequent learning to press a lever to earn food in the second chamber.
From page 35...
... They suggested that detrimental effects on performance following exposure to unpredictable uncontrollable stressors, (which occur due to the substantial effort required to adapt to these aversive events) would leave one less able to cope with subsequent demands and frustrations, because predictable and controllable stresses were viewed as less aversive adaptations of these stresses, would presumably require less effort and, therefore, would be less likely to impair post-stimulation performance.
From page 36...
... . These studies typically involve approximately 25 minutes exposure to 108-110 dB random in~cermit~cent bursts of broad band conglomerate noise made up of a nuder of typical urban sounds.
From page 37...
... . Although the Glass and Singer research suggests that post-stimulation effects occur only following unpredictable noise, at least two studies reported similar deficits following exposure to high intensity steady-state continuous noise.
From page 38...
... found in a forced reaction time experiment that those required to respond to 100 lights/minute had less tolerance for frustration following task completion than those responding to 50 lights/minute. Hartley (1973)
From page 39...
... Whereas females who had been exposed to high levels of density performed more poorly on the S troop test than did their low-density counterparts, males performed better after high than after low density. Glass and Singer also have reported that there are post-exposure deficits in performance following a variety of other stressful conditions, which include electric shock, a frustrating experience with a bureaucracy, and an experience of arbitrary or sex discrimination.
From page 40...
... that the post-exposure deficits in performance are more likely to occur following exposure to an unpredictable, rather than to a predictable stress. In view of the abundance of data produced experimentally indicating post-exposure effects on subsequent performance, it is not surprising that investigators have also studied the effects of these stressful experiences in
From page 41...
... A subsequent study of children attending school in the air corridor of a busy metropolitan airport (Cohen et al., 1980) indicated that children living and attending school in the air corridor were poorer on both a simple and a difficult problem-solving task and were more likely to give up the task than their quiet-neighborhood controls.
From page 42...
... They occur as a result of a wide range of stressors, such as noise, electric shock, social density, etc. Interventions that increase control and predictability are effective in reducing these effects.
From page 43...
... Levine (1966) also reported a study in which, as electric shock increased in an avoidance learning paradigm, the ability of the animals to learn declined beyond
From page 44...
... was associated with slow reaction times, and high conductance was associated with fast reaction times. However, beyond the optimal range of palmer conductance, reaction time once again became slower.
From page 45...
... has repeatedly stated that at the level of a specific individual, the problem is to determine what kind of stress evokes what kind of stress response in what kind of person. What does emerge from the theoretical considerations presented here and from the experimental data on the biological and behavioral consequences of stress, is that control is a major mechanism by which organisms can effectively deal with
From page 46...
... Page 46 stressful conditions; and that the absence of control or loss of control can indeed have profound and permanent effects on individual performance on a wide variety of tasks.


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