Background:Validated and reliable tests are necessary to evaluate the effectiveness of, for example, (data-driven) selection, education and training, and human enhancement interventions, in high-risk professions like the military. Therefore, the current paper describes the development of a test for measuring dismounted soldiers' ability to make quick decisions in unpredictable close-quarters battle (room-clearing) contexts. Methods:A group of 15 Dutch Marines Special Operation Forces (SOF) operators and 17 Dutch Army SOF-support specialists individually performed a test in Virtual Reality (VR). Participants could physically walk, shoot, and verbally communicate with opponents. Fifteen performance items indicative of situational awareness (SA) of threats were scored by subject-matter experts, shoot/do not shoot errors were counted, and visual response times (VRTs) in shooting were obtained. Eight room-clearing scenarios were performed twice: once before (pretest) and once following a night of sleep deprivation (posttest), to measure test-retest reliability and sensitivity to a typical military stressor. Results:The SA items demonstrated adequate internal consistency, and there was a significant test-retest correlation. SOF operators had significantly higher SA item scores (p < 0.05) and made fewer shoot/do not shoot errors (p < 0.05) than SOF-support specialists. VRTs showed no significant test-retest correlation or effects. Sleep deprivation had no significant effect on any of the performance measures. Conclusion:The developed test methodology offers a means to obtain embedded measures of SA, as well as shoot/do not shoot decisions, but VRT measurement appeared to be unreliable. Performance measures were not sensitive to effects of sleep deprivation, possibly due to a counteracting learning effect and limitations in timing of the post-test. The reliability checks of the SA measures were promising, indicating that this study contributes to advancing methodologies for evaluating human enhancement interventions on performance in operationally relevant settings. It is advised to incorporate team performance measures to enhance realism and integrate digitally obtained metrics to minimize observer bias.

INTRODUCTION:Next-generation air force operations increasingly depend on advanced flight systems, which raises questions about their impact on aircrew workload. Physiological measures enable continuous, objective, and unobtrusive assessments, overcoming some limitations of self-report measures. We investigated whether electroencephalogram, electrocardiogram, and electrodermal activity predicted subjective Rating Scale of Mental Effort (RSME) ratings of fighter pilots during an operationally relevant mission in an F-16 simulator. METHODS:The mission included three flight segments expected to induce increasingly higher workload, with a mathematical task of two arithmetic difficulty levels added to each segment. This approach allowed us to explore whether physiology distinguished workload both across and within flight segments. RESULTS:Subjective ratings confirmed an increase in workload throughout the mission (ΔRSME = 22). However, our manipulation of arithmetic difficulty was less effective: neither subjective ratings nor arithmetic performance significantly differentiated simple and complex calculations (ΔRSME = 5; Δreaction time = 0.02 s, Δunsuccessful trials = 0.5). None of our physiological measures-frontal theta power (Δ0.08, Δ-0.07 mV), parietal alpha power (Δ-0.16, Δ0.14 mV), heart rate (Δ0.01, Δ-0.02 bpm), skin conductance response (Δ0.0, Δ0.0 mS), and skin conductance peaks (Δ0.3, Δ0.2)-systematically distinguished flight segments or arithmetic difficulty, respectively. Physiology also did not significantly predict subjective workload (R2 = 2.2%). DISCUSSION:Large interindividual variability, use of workload management strategies, and relatively small task demand differences may explain the null results. Our study underscores the complexity of workload assessment in an operational setting and offers methodological insights that may inform future ecologically valid research. Reuten AJC, Bruin J, Ledegang WD, Groen EL, Houben MMJ, Cornelisse E-J, Bottenheft C. Physiological and subjective assessment of fighter pilot mental workload. Aerosp Med Hum Perform. 2026; 97(8):592-600.

Theoretical models on cognitive performance predict that performance breaks down at higher task load levels, because of limiting cognitive resources. Experimental validation of these models is scarce, and they often don’t accommodate effects of invested effort and/or stressors. We experimentally measured a performance-curve as a function of increasing task load using a Tetris game. In addition, we investigated if performance breakdown occurs at different task load levels in the presence of a stressor. We hypothesized that an external stressor would shift the performance-curve to the left (i.e. lower task load levels) while maintaining the same form. Twenty-one participants completed one training day and two test days (data collection: 2023). During training, an individual break-off level on the Tetris game was determined with a staircase method. Subsequently, on the two test days participants played nine predetermined task load levels on and around their break-off level. On one test day they were exposed to heat load, and on the other test day to room temperatures. Task load levels and test room temperature were counterbalanced. The results show that a sigmoid model is successful in fitting the performance decline pattern at high task load levels. Heat load did not seem to affect the parameters of the sigmoid curves. This study provides experimental evidence for a performance-curve as a function of increasing task load, resembling the right side of the classic inverted U-curve. Contrary to our expectation, we did not find evidence for a stressor-induced shift of the individual performance-curve, presumably because the increase in body core temperature (TC) was insufficient to affect cognitive performance. Tetris seems a suitable tool to reproduce the performance-curve, and to perform research into factors that may affect the relation between mental effort and performance.

With the purpose of identifying a sensitive, robust, and easy-to-measure set of biomarkers to assess stress reactivity, we here study a large set of relatively easy to obtain markers reflecting subjective, autonomic nervous system (ANS), endocrine, and inflammatory responses to acute social stress (n=101). A subset of the participants was exposed to another social stressor the next day (n=48) while being measured in the same way. Acute social stress was induced following standardized procedures. The markers investigated were self-reported positive and negative affect, heart rate, electrodermal activity, salivary cortisol, and ten inflammatory markers both in capillary plasma and salivary samples, including IL-22 which has not been studied in response to acute stress in humans before. Robust effects (significant effect in the same direction for both days) were found for self-reported negative affect, heart rate, electrodermal activity, plasma IL-5, plasma IL-22, salivary IL-8 and salivary IL-10. Of these seven markers, the participants’ IL-22 responses on the first day were positively correlated to those on the second day. We found no correlations between salivary and capillary plasma stress responses for any of the ten cytokines and somewhat unexpectedly, cytokine responses in saliva seemed more pronounced and more in line with previous literature than cytokines in capillary plasma. In sum, seven robust and easy to obtain biomarkers to measure acute stress response were identified and should be used in future stress research to detect and examine stress reactivity. This includes IL-22 in plasma as a promising novel marker.

This study investigates how cognitive performance is affected by the combination of two stressors that are operationally relevant for helicopter pilots: heat load and hypobaric hypoxia. Fifteen participants were exposed to (1) no stressors, (2) heat load, (3) hypobaric hypoxia, and (4) combined heat load and hypobaric hypoxia. Hypobaric hypoxia (13,000 ft) was achieved in a hypobaric chamber. Heat load was induced by increasing ambient temperature to ∼28 °C. Cognitive performance was measured using two multitasks, and a vigilance task. Subjective and physiological data (oxygen saturation, heart rate, core- and skin temperature) were also collected. Mainly heat load caused cognitive performance decline. This can be explained by high subjective heat load and increased skin temperature, which takes away cognitive resources from the tasks. Only the arithmetic subtask was sensitive to hypobaric hypoxia, whereby hypobaric hypoxia caused a further performance decline in addition to the decline caused by heat load.Practitioner summary: Little is known about how multiple environmental stressors interact. This study investigates the combined effects of heat load and hypobaric hypoxia on cognitive performance. An additive effect of heat load and hypobaric hypoxia was found on a arithmetic task, which may be attributed to independent underlying mechanisms.

Introduction When multiple individuals are presented with narrative movie or audio clips, their electrodermal activity (EDA) and heart rate show significant similarities. Higher levels of such inter-subject physiological synchrony are related with higher levels of attention toward the narrative, as for instance expressed by more correctly answered questions about the narrative. We here investigate whether physiological synchrony in EDA and heart rate during watching of movie clips predicts performance on a subsequent vigilant attention task among participants exposed to a night of total sleep deprivation. Methods We recorded EDA and heart rate of 54 participants during a night of total sleep deprivation. Every hour from 22:00 to 07:00 participants watched a 10-min movie clip during which we computed inter-subject physiological synchrony. Afterwards, they answered questions about the movie and performed the psychomotor vigilance task (PVT) to capture attentional performance. Results We replicated findings that inter-subject correlations in EDA and heart rate predicted the number of correct answers on questions about the movie clips. Furthermore, we found that inter-subject correlations in EDA, but not in heart rate, predicted PVT performance. Individuals' mean EDA and heart rate also predicted their PVT performance. For EDA, inter-subject correlations explained more variance of PVT performance than individuals' mean EDA. Discussion Together, these findings confirm the association between physiological synchrony and attention. Physiological synchrony in EDA does not only capture the attentional processing during the time that it is determined, but also proves valuable for capturing more general changes in the attentional state of monitored individuals.

Background: Sleep deprivation (SD) and acute social stress are common, often unavoidable, and frequently co-occurring stressors in high-risk professions. Both stressors are known to acutely induce inflammatory responses and an increasing body of literature suggests this may lead to cognitive impairment. This study examined the combined effects of total SD and acute social stress on cognitive performance and took a comprehensive approach to explore their (shared) underlying mechanism leading to cognitive decline. Method: We recorded cognitive performance on a response inhibition task and a multitask and monitored a range of inflammatory, psychophysiological and self-reported markers in 101 participants, both before and after one night of either sleep (control group: N = 48) or SD (N = 53), and both before and after a social stressor (Trier Social Stress Test). Results: SD decreased cognitive performance. The social stress test also results in cognitive performance decline in the control group on the response inhibition task, but improved rather than decreased performance of sleep deprived participants on both tasks. The subjective ratings of mental effort also reflect this antagonistic interaction, indicating that the social stressor when sleep-deprived also reduced mental effort. In the inflammatory and physiological measures, this pattern was only reflected by IL-22 in blood. SD reduced blood IL-22 concentrations, and the social stress reduced IL-22 in the control group as well, but not in sleep-deprived participants. There were no interactive effects of SD and social stress on any other inflammatory or psychophysiological measures. The effects of the social stress test on autonomic measures and subjective results suggest that increased arousal may have benefited sleep-deprived participants’ cognitive performance. Discussion: SD generally decreased cognitive performance and increased required mental effort. By contrast, the isolated effects of a social stressor were not generic, showing a positive effect on cognitive performance when sleep deprived. Our study is the first that studied combined effects of sleep deprivation and acute social stress on cognitive performance and inflammatory markers. It provides a comprehensive overview of effects of these stressors on a range of variables. We did not show unequivocal evidence of an underlying physiological mechanism explaining changes in performance due to (the combination of) sleep deprivation and social stress, but consider IL-22 as a possible cytokine involved in this mechanism and certainly worth following up on in future research.

Real-time physiological stress monitoring would be a relevant addition to virtual reality (VR) training for high-risk professions, such as the military. VR is highly suitable for the implementation of such monitoring due to the controlled environment and the already used wearables. However, physiological stress measurements suffer from distortion due to physical activity. Therefore, we tested whether we can use accelerometry to correct non-invasively measured heart rate (HR) for physical activity in 23 soldiers who performed three room-clearing VR scenarios. These scenarios were dynamic, in that soldiers moved around in the VR environment by walking around in the real environment. In contrast to uncorrected HR, and HR corrected by subtracting baseline HR measured when walking, the accelerometry-corrected HR was able to significantly predict the participants’ self-reported stress in the scenarios, p = 0.047, R 2 = 0.11. Whereas uncorrected HR significantly predicted self-reported physical demand, p = 0.028, R 2 = 0.09, the accelerometry-corrected HR did not. All HR measures significantly predicted self-reported mental effort, which was most strongly the case for uncorrected HR, p < 0.001 R 2 = 0.42. These findings, in combination with the methods’ low sensitivity to motion artifacts and non-invasiveness, are very promising for its use to monitor stress in real-time during dynamic VR training scenarios.

The current study explores whether different stressors in a virtual reality (VR) military training scenario cause increases in physiological stress. This would validate the use of VR simulation for stress training, as well as the physiological monitoring of trainees for educational purposes. Military cadets (n = 63) performed a patrol scenario (military convoy) in which they answered questions about their surroundings. Stressors (task difficulty, noise, lighting changes, social evaluations, electric muscle stimulation, and a simulated attack on the convoy) were stepwise added in four phases. Electrocardiogram, blood pressure, electrodermal activity, cortisol, and the cadets' subjective threat/challenge appraisal were measured. We found that only the first phase caused a significant increase in physiological stress, as measured with heart rate, heart rate variability, and electrodermal activity. Physiological stress appeared to stay high in the second phase as well, but decreased to baseline level in the third and fourth phases, even though these phases were designed to be the most stressful. Cadets classified as threat responders based on physiological data (n = 3) scored significantly higher on subjective threat/challenge appraisal than those classified as challenge responders (n = 21). It seems that in the tested VR training scenario, the novelty of the scenario was the only effective stress stimuli, whereas the other implemented stressors did not cause a measurable physiological response. We conclude that if VR training scenarios are to be used for stress training, these should confront trainees with unpredictable but context-specific demands.

Background: The effectiveness of an airflow system in preventing entrainment of particles carrying micro-organisms from the periphery of an operating room (OR) or instrument layup room (ILR) is affected by many variables. It is suspected that differences in the design of the systems affect the effective protection ratio (EPR): the ratio of the size of the protected area to the surface area of the supply canopy. However, no analysis has yet been done to determine which design variables have a significant effect on this ratio. Aim: To evaluate which design variables have a significant effect on the performance of airflow systems (EPR) in ORs and ILRs. Methods: All general and teaching hospitals in the Netherlands (N = 77) were asked to provide data from their standardized (at-rest measurement method) compulsory systems assessment reports for ORs and ILRs. Nineteen hospitals (25%) with a total of 22 hospital sites supplied information of sufficient completeness and homogeneity, resulting in measurement data for 101 ORs and 23 ILRs. This dataset was analysed using Statistical Package for Social Sciences. Findings: For ORs, important predictors for the EPR were: shape of the canopy; air speed under the supply canopy; height of the canopy screen; type of system; and size of the canopy. These significant predictors (P < 0.05) explain 48% of the outcome in the dataset. For ILRs, significant predictors for the EPR were: the position of exhaust air terminals; height of the canopy screen; and size of the canopy. These significant predictors explain 66% of the outcome in the dataset. Conclusion: On the basis of the dataset available for analysis, it is concluded that the ratio of the size of the protected area to the surface area of the supply canopy (EPR) improves with the presence and the height of a screen around the canopy, the surface area of the supply canopy, and the air speed of the supply air under the canopy. This information can be used as guidance for the future design of unidirectional displacement airflow systems. (C) 2019 The Healthcare Infection Society. Published by Elsevier Ltd. All rights reserved.

BACKGROUND: Royal Netherlands Air Force (RNLAF) helicopter aircrew get Helicopter Underwater Egress Training (HUET) using a Modular Egress Training Simulator (METS™) in order to be prepared for escaping the aircraft when ditching into water. In the current situation the retraining intervals are only chosen on an arbitrary basis for different backgrounds of the crew (maritime and regular flight crew). The frequency of refresher training depends on the expected degree of retention, but evidence-based research on required intervals between refresher courses is scarce. Ideally, training should be based on the amount of retention of acquired competencies.METHODS: Retrospective questionnaires were filled in by 132 helicopter aircrew who followed the HUET course(s) at the Survival Evasion Resistance and Escape (SERE) school in Gilze-Rijen (Netherlands). They assessed themselves on competencies and gave their opinion on the preferred interval.RESULTS: Maritime crew report increasing competence levels with the number of refresher courses followed. According to the opinion of all aircrew, retraining intervals may take longer than 18 (first refresher) to 30 mo (fourth refresher). Maritime and regular flight crew differ in preferred retraining intervals (up to 22 mo and up to 33 mo, respectively).DISCUSSION: This study provides indications to reconsider the retraining interval and to differentiate between maritime and regular flight crew based on aircrew's opinions and self-assessments. As competence levels still increase with the number of courses followed, it is recommended to reconsider the current fixed intervals of once a year or once every 3 yr for maritime and regular flight crew, respectively.Bottenheft C, Oprins EAPB, Houben MMJ, Meeuwsen T, Valk PJL. Self-assessed preferred retraining intervals of Helicopter Underwater Egress Training (HUET). Aerosp Med Hum Perform. 2019; 90(9):800-806.

PurposeInformal learning is seen as the most important way to acquire and develop the skills and competencies required for work. The Dutch Defence organisation (DDO) aims to use the opportunities for development of employees that informal learning offers better and is looking for suitable interventions. Four possible interventions to improve informal learning were developed, based on factors that influence informal learning. The purpose of this paper is to assess how Dutch Military personnel rate these interventions and to gather their opinions and preferences per intervention.Design/methodology/approachA total of 96 employees completed an online mixed-method vignette study. In the questionnaire, the four interventions were introduced by a visualisation in the form of a “comic strip” (vignette), and respondents’ perceptions were measured with multiple choice and open-ended questions.FindingsRespondents clearly indicated a preference for two of the four interventions, i.e. informal mentorship and safe learning environment. They provided numerous advantages and disadvantages per intervention. They also indicated that all four interventions could be used throughout the entire Dutch Defence Organisation.Research limitations/implicationsThe results contribute to a thoughtful design of interventions that can be used in practice; also, the interventions can be improved based on the advantages, disadvantages and suggestions formulated by the respondents in this vignette study.Originality/valueThe designs of interventions are studied in a systematic way by the target population before they are actually developed and implemented. In addition, the use of “comic strips” and visualisations in vignette studies is quite original.

There is a growing interest in the application of psychophysiological signals in more applied settings. Unidirectional sensory motor rhythm-training (SMR) has demonstrated consistent effects on sleep. In this study the main aim was to analyze to what extent participants could gain voluntary control over sleep-related parameters and secondarily to assess possible influences of this training on sleep metrics. Bidirectional training of SMR as well as heart rate variability (HRV) was used to assess the feasibility of training these parameters as possible brain computer interfaces (BCI) signals, and assess effects normally associated with unidirectional SMR training such as the influence on objective and subjective sleep parameters. Participants (n = 26) received between 11 and 21 training sessions during 7 weeks in which they received feedback on their personalized threshold for either SMR or HRV activity, for both up- and down regulation. During a pre- and post-test a sleep log was kept and participants used a wrist actigraph. Participants were asked to take an afternoon nap on the first day at the testing facility. During napping, sleep spindles were assessed as well as self-reported sleep measures of the nap. Although the training demonstrated successful learning to increase and decrease SMR and HRV activity, no effects were found of bidirectional training on sleep spindles, actigraphy, sleep diaries, and self-reported sleep quality. As such it is concluded that bidirectional SMR and HRV training can be safely used as a BCI and participants were able to improve their control over physiological signals with bidirectional training, whereas the application of bidirectional SMR and HRV training did not lead to significant changes of sleep quality in this healthy population.

Background: Operating lamps are often seen as the most disruptive factors within the protective area in the operating theater (OT). The effect of the operation lamps (with different shapes) should be demonstrated in an OT by trial, since research on the effects of the lamps is still limited. Objectives: The main aim of this study was to determine the effects of a skirt, different lamps, and the position of the lamp on the protected area. Methods: The concentration of airborne particles was measured under different circumstances, in order to determine the size and quality of the protected area. This entrainment/segregation test is based on the deliberate and controlled emission of particles outside the zone that is protected. Findings and Conclusions: The degree of protection (DP) at the center of the protected area was higher for the case with the skirt. This skirt stimulates more down flow and prevents the early entry of particles into the protected area. It can also be concluded that Lamp Y, due to its open shape, has the most positive effect on the DP at the center. It has also been shown that the position of the lamp has an effect on the protected area.

Introduction: Dealing with high levels of emotional, cognitive and/or physiological stress is an essential skill of soldiers. The increasing development of both gaming and simulation technology and applied miniaturized sensors and monitoring technology represents a great opportunity for advancing performance in physiological and psychological resilience of employees that might experience high levels of stress during their deployments. Therefore, the Dutch Ministry of Defence launched a research program that combines these new technologies to improve the Forces' capability of stress training and stress evaluation environments. To this aim, a simulation, gaming and measurement environment was developed containing a controllable Virtual Reality Monitoring (VRM) platform.

Background: Switching off air handling systems in operating theaters during periods of prolonged inactivity (eg, nights, weekends) can produce a substantial reduction of energy expenditure. However, little evidence is available regarding the effect of switching off the air handling system during periods of prolonged inactivity on the air quality in operating theaters during operational periods. The aim of this study is to determine the amount of time needed after restarting the ventilation system to return to a stable situation, with air quality at least equal to the situation before switching off the system.Methods: Measurements were performed in 3 operating theaters, all of them equipped with a unidirectional downflow(UDF) system. Measurements (particle counts of emitted particles with a particle size >= 0.5 mu m) were taken during the start-up of the ventilation system to determine when prespecified degrees of protection were achieved. Temperature readings were taken to determine when a stable temperature difference between the periphery and the protected area was reached, signifying achievement of a stable condition.Results: After starting up the system, the protected area achieved the required degrees of protection within 20 minutes (95% upper confidence limit). A stable temperature difference was achieved within 23 minutes (95% upper confidence limit). Both findings lie well within the period of 25 minutes normally required for preparations before the start of surgical procedures.Conclusions: Switching off the ventilation system during prolonged inactivity (during the night and weekend) has no negative effect on the air quality in UDF operating theaters during normal operational hours. (C) 2017 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved.

Objective: The main aim of this research was to identify the impact of design characteristics (DCs) of a patient room on self-reported patient well-being. Background: This knowledge enables the construction of healing environments focusing on DCs that maximize well-being. Six themes were identified in literature that create healing environments: spatial comfort, safety and security, autonomy, sensory comfort, privacy, and social comfort. We wondered what themes and associated DCs should be prioritized if needed to maximize well-being. Method: The physical environment of patient rooms in four hospital locations was measured and patients who stayed in these rooms were asked to evaluate the room design on above mentioned themes and its contribution to their well-being. We used a machine-learning technique and regression analysis to find relations between the physical environment of a patient room and patient well-being. Results and Conclusions: We found that spatial comfort, safety and security, autonomy, and associated DCs have the strongest ability to influence patient’s self-reported well-being in a patient room. Privacy appears to have the smallest influence.