While running a selection procedure, 27 male Belgian Special Forces candidates, with a mean age of 27.4 years (SD = 5.1), were randomly assigned to a no-stress control (n = 14) or a high-intensity stress group (n = 13). Participants in the latter group were exposed to an extremely strenuous mock prisoner of war (POW) exercise. Immediately after stress or control treatment, working memory and visuo-spatial declarative memory performances were measured by the digit span (DS) test and the Rey-Osterrieth complex figure (ROCF), respectively. Concurrently, stress levels were assessed by obtaining salivary cortisol measurements and subjectively by the NASA Task Load Index (TLX). As expected, exposure to high-intensity stress led to both robust cortisol increases and significant differences in TLX scores. Stress induction also significantly impaired DS and ROCF performances. Moreover, delta cortisol increases and ROCF performance in the POW stress group showed a significant negative correlation, while DS performances followed the same tendency. Summarizing, the current findings complement and extend previous work on hormonal stress effects, and the subsequent performance deterioration on two memory tests in a unique high-intensity stress environment.

The present field experiment examined how multi-trial visuo-spatial learning and memory performance are impacted by excessive arousal, instigated by a potentially life-threatening event (i.e., a first parachute jump). Throughout a parachute training activity, subjective and neuroendocrine (i.e., cortisol) stress levels were assessed of 61 male military cadets who were randomly assigned to a control (n = 30) or a jump stress condition (n = 31). Poststress learning and memory capacity was assessed with a 10-trial path-learning task that permitted emergence of learning curves. Pre-activity cortisol concentrations indicated a significant neuroendocrine anticipatory stress response in the stress group. Following parachuting, subjective stress levels and salivary cortisol reactivity differed significantly between groups. Visuo-spatial path-learning performance was impaired significantly after jump stress exposure, relative to the control group. Moreover, examination of the learning curves showed similar learning and memory performance at onset of the trials, with curves bifurcating as the task became more complex. These findings are in accordance with leading theories that acknowledge a moderating effect of task complexity. In sum, the present study extends knowledge concerning anticipatory stress effects, endogenously instigated cortisol reactivity, and the influence of extreme arousal on visuo-spatial path learning.

Evidence links the personality trait hardiness to both mental (MH) and physical health (PH) status, but few unifying models delineate interrelationships of these variables. The first purpose of this study was to examine the association of hardiness to MH and PH in military men. Second, we tested the hypothesis that MH would mediate the association of hardiness with PH. Identical measures were collected in two separate, demographically-similar samples (n = 65 and n = 55). All subjects completed a background questionnaire, the Dispositional Resilience Scale-15 and the Short Form 36 Medical Outcomes Survey. Associations between hardiness, PH and MH were examined using regression-based mediation analyses followed by the Sobel test of indirect effects. In the total sample, hardiness predicted PH in an initial regression model (β = 0.37, p < .001). When MH was added to the model, however, PH's influence was substantially attenuated and no longer significant (β = 0.06, p > .05). A Sobel test of significance confirmed a mediated effect (p < .001). Similar patterns were observed in each individual sample. Hardiness is associated with PH in military men, and this relationship is mediated by MH.

A field experiment was organized during a handgun shooting workshop for armed officers (N ϭ 36). In-depth stress analyses involved anticipatory distress, subjective stress, and salivary cortisol reactivity triggered by reality-based handgun shooting practice and, more specifically, by being in an uncontrollable situation with the risk of being shot at. Subsequently, the study examined to what extent exposure to reality-based stress affected working memory performances and self-perceived active learning. As expected, the risk of being shot at caused more anticipatory distress, subjective stress, and increasingly triggered cortisol secretion. Further results showed that, although stress endurance deteriorated working memory performance, participants in the high-realism group simultaneously self-perceivably learned more (i.e., acquired task-relevant

Research on the effect of acute stress and high levels of glucocorticoids on memory has largely focused on memory tasks involving the medial temporal lobe (e.g., declarative memory). Less is known, however, about the effects of stress and glucocorticoids on more strategic memory processes regulated by the prefrontal cortex (e.g., source monitoring). In the current study, the authors investigated whether exposure to acute psychosocial stress would result in altered source monitoring performance relative to the performance of a nonstressed control group. To this end, the authors assigned nonsmoking, healthy, young men to either a stress (n = 22) or a control (n = 18) condition, after which the men were given an internal source monitoring test. Results show that relative to control participants, stressed participants made fewer source monitoring errors. This study suggests that stress may have differential effects on memory, depending on whether the memory test is regulated by the prefrontal cortex or the medial temporal lobe.

The aim of this paper is twofold. First, it explores delayed effects of high endogenously evoked cortisol concentrations on visuo-spatial declarative memory. Subsequently, it applies multiple mediation (MM) analyses to reveal path processes between stress and cognitive performance in a sample of 24 male Special Forces (SF) candidates (mean age = 27.0 years, SD = 4.1). The SF candidates were randomly assigned to a control (n = 12) or an intense stress group (n = 12), and cortisol secretion for the intense stress condition was triggered by a brusque 60 min prisoner of war exercise. Stress exposure provoked robust increases in cortisol concentrations and a significant decline in immediate recall performance, measured with the Rey-Osterrieth Complex Figure (ROCF). The relative retrieval differences in regard to the ROCF persisted even after a recovery period of 24 h, as both groups showed similar levels of memory decline over 24 h. Next, the study applied a MM design that involved distribution-independent asymptotic and resampling strategies to extend traditional bivariate analyses. MM results showed that ROCF performance was mediated by increases in cortisol concentrations. Considering the studied variables, the current analysis was the first to provide statistical support for the generally accepted thesis that cortisol secretion in itself, rather than subjective strain or the experimental treatment, affects cognitive performance. The revelation of such path processes is important because it establishes process identification and may refine existing paradigms.

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Potential applications of this research include the introduction of biomarker assessments in human factors research and the design, based on reality-based practice, of effective training procedures for high-reliability professionals.