A new approach to manipulating aviator workload: A case for individualizing workload manipulations.

The present study sought to manipulate workload individually for participants to evaluate whether individual manipulations of workload produces similar subjective ratings and performance changes across participants. Participants included eight Army-rated rotary-wing aviators who presented to the laboratory for two separate visits. During the first visit, individual responses to workload were determined, and during the second visit, individually manipulated high workload flights were completed. Outcome measures included flight performance and subjective workload ratings. Data were examined at the group and individual level. Subjective ratings of workload endorsed the individual workload manipulations, while performance data provided some additional support. By taking an individualized approach such as this, researchers and practitioners may be better able to control for individual differences influencing workload. This has important implications for system design and testing, development of new intervention technologies, and assessing methods for operator monitoring.

Measuring the Domain Specificity of Workload Using EEG: Auditory and Visual Domains in Rotary-Wing Simulated Flight.

OBJECTIVE: The overarching objective was to evaluate whether workload sensory-domain specificity could be identified through electroencephalogram (EEG) recordings during simulated rotary-wing operations. BACKGROUND: Rotary-wing aviators experience workload from different sensory domains, although predominantly through auditory and visual domains. Development of real-time monitoring tools using psychophysiological indices, such as EEG recordings, could enable identification of aviator overload in real time. METHOD: Two studies were completed, both of which recorded EEG, task performance, and self-report data. In Study 1, 16 individuals completed a basic auditory and a basic visual laboratory task where workload was manipulated. In Study 2, 23 Army aviators completed simulated aviation flights where workload was manipulated within auditory and visual sensory domains. RESULTS: Results from Study 1 found differences in frontal alpha activity during the auditory task, and that alpha and beta activities were associated with perceived workload. Frontal theta activity was found to differ during the visual task while frontal alpha was associated with perceived workload. Study 2 found support for frontal beta activity and the ratio of beta to alpha + theta to differentiate level of workload within the auditory domain. CONCLUSION: There is likely a role of frontal alpha and beta activities in response to workload manipulations within the auditory domain; however, this role becomes more equivocal when examined in a multifaceted flight scenario. APPLICATION: Results from this study provide a basis for understanding changes in EEG activity when workload is manipulated in sensory domains that can be used in furthering the development of real-time monitoring tools.

Symptoms of convergence and accommodative insufficiency predict engagement and cognitive fatigue during complex task performance with and without automation.

Deficits in the accommodative and/or vergence responses have been linked with inattentive behavioral symptoms. While using automated systems (e.g., self-driving cars, autopilot), operators (e.g., drivers, pilots, soldiers) visually monitor displays for critical changes, making deficits in the accommodative and/or vergence responses potentially hazardous for individuals remaining actively engaged in the task at hand. The purpose of this study was to determine if symptoms of accommodative-vergence deficits predict an individual's level of task engagement and cognitive fatigue while performing a flight simulation task with or without automation. Eighty-four participants performed a flight simulation task with or without automation. Prior to task completion, self-report accommodative-convergence deficit symptoms were assessed with the Convergence Insufficiency Symptom Survey (CISS). Before and after the flight simulation task participants rated their task engagement and cognitive fatigue. Electroencephalographic activity (EEG) was recorded concurrently during task performance. Results showed that higher scores on the CISS were related to increased feelings of fatigue and decreased ratings of task engagement. The CISS was also positively related to parietal-occipital fast alpha power during the last 10 min of the task for participants using automation, suggesting increased cortical idling. CISS scores did not predict performance. Results have implications for optimizing operator cognitive states over extended task performance.

Viability of tDCS in Military Environments for Performance Enhancement: A Systematic Review.

INTRODUCTION: Transcranial electrical stimulation (tES) as a method of cognitive enhancement in both diseased and healthy individuals has gained popularity. Its potential for enhancing cognition in healthy individuals has gained the interest of the military. However, before it being implemented into military training or operational settings, further work is needed to determine its efficacy and safety. Although a considerable amount of literature exists, few studies have specifically evaluated its use in enhancing cognition relative to operational, military tasks. Therefore, in a first step to evaluate its efficacy, we completed a systematic literature review of studies using transcranial direct current stimulation (tDCS), a type of tES, to enhance cognitive processes in healthy individuals. METHODS: A systematic literature review was conducted to identify literature published between 2008 and 2018 that used a method of tES for cognitive enhancement. As part of a larger literature review effort, 282 articles were initially retrieved. These were then screened to identify articles meeting predetermined criteria, to include those using various methods of tES, resulting in 44 articles. Next, the articles were screened for those using tDCS or high-definition tDCS, resulting in 34 articles for review and information extraction. RESULTS: Of the 34 articles reviewed, 28 reported some degree of enhancement (eg, improved accuracy on tasks and reduced reaction times). Areas of cognitive enhancements included executive functioning, creativity/cognitive flexibility, attention/perception, decision-making, memory, and working memory. However, the precise outcomes of enhancement varied given the range in tasks that were used to assess the constructs. Additionally, the stimulation parameters in terms of intensity applied, duration of stimulation, and brain region targeted for stimulation varied. CONCLUSIONS: The conclusions to be drawn from this systematic literature review include the identification of a brain region for targeting with stimulation to enhance a broad range of cognitive constructs applicable to military tasks, as well as stimulation parameters for duration and intensity. The dorsolateral prefrontal cortex was most frequently targeted in the studies that found enhanced performance across several cognitive constructs. Stimulation intensities of 2 mA and durations of 20 minutes or longer appeared frequently as well. Although several parameters were identified, further work is required before this type of technology can be recommended for operational use.

The effects of dynamic workload and experience on commercially available EEG cognitive state metrics in a high-fidelity air traffic control environment.

The current study evaluated the validity of commercially available electroencephalography (EEG) cognitive state metrics of workload and engagement in differentially experienced air traffic control (ATC) students. EEG and pupil diameter recordings were collected from 47 ATC students (27 more experienced and 20 less experienced) during a high-fidelity, variable workload approach-control scenario. Scenario workload was manipulated by increasing the number of aircraft released and the presence of a divided attention task. Results showed that scenario performance significantly degraded with increased aircraft and the presence of the divided attention task. No scenario performance differences were found between experience groups. The EEG engagement metric significantly differed between experience groups, with less experienced controllers exhibiting higher engagement than more experienced controllers. The EEG workload metric and pupil diameter were sensitive to workload manipulations but did not differentiate experience groups. Commercially available EEG cognitive state metrics may be a viable tool for enhancing ATC training.

Rest and Activity Patterns of Army Aviators in Routine and Operational Training Environments.

INTRODUCTION: Fatigue continues to be a leading cause of military aviation mishaps. Several factors, including reversed shift missions, can negatively affect sleep patterns and increase the risk of fatigue due to sleep restriction. Currently, there is a lack of objective data regarding the current rest and activity patterns of military aviators across multiple operational conditions. The purpose of this descriptive study was to document the rest and activity patterns of U.S. Army aviators in operational training and garrison (routine) environments using wrist-worn actigraphy devices.METHODS: Actigraphy data were collected from U.S. Army aviators in training (N = 20) and garrison (N = 77) environments for a period of 1 wk.RESULTS: Results from this study indicate that 90% of subjects in the training environment, even after accounting for small sleep bouts during the day, averaged less than the recommended 8 h of sleep daily across the recording week. Approximately half of subjects in garrison averaged less than 8 h of sleep daily after accounting for smaller sleep bouts. Sleep efficiency was relatively high and similar in both groups (∼84%). Subjects in the training group averaged significantly more time awake and less time sleeping than those in the routine garrison group. Moreover, subjects in training were exposed to more light during sleep than those in garrison.DISCUSSION: Training environments that are representative of deployed conditions restrict aviator restorative sleep. These results highlight the importance of continued research on aviator sleep and fatigue mitigation in operational environments.Bernhardt KA, Kelley AM, Feltman KA, Curry IP. Rest and activity patterns of Army aviators in routine and operational training environments. Aerosp Med Hum Perform. 2019; 90(1):48-52.