United States Army Aeromedical Research Lab

The Multi-Attribute Task Battery (MATB) is a computerized flight task consisting of four subtasks performed concurrently. These subtasks include the system monitoring, communications, resource management, and target tracking tasks. Where the system monitoring, and communications tasks are discrete operator engaged task, and the resource management and target tracking are continuous operator engaged tasks. The MATB has been used as a research tool to evaluate the performance and cognitive workload of operators; however, previous iterations of the MATB did not include a generalized scoring index. As such, performance could only be considered for each subtask individually and not overall. To address this gap, these works focused on developing a composite scoring index for the United States Army Aeromedical Research Laboratory (USAARL) MATB. The first step was to create a discrete task load metric that is used to track the number of active discrete subtask load events (as continuous events are always active and hence redundant for this purpose). Then, the percentage of sample times spent at each number of discrete loads is computed resulting in a load profile. This load profile is used to determine a load classification of low, normal, or high throughout the simulation. Next the performance parameters of the active subtasks are averaged at completion to compute a performance classification of below standard, standard, or above standard. A matrix is then used to assign an overall composite score based on the frequency of time spent on each subtask load and performance classifications. The composite scoring index could have great value to research when combined with MATB synchronous physiological parameter data for cognitive workload estimations.

Hearing loss can compromise U.S. Army aviators' performance, safety, and situational awareness, resulting in increasing mental workload and listening effort. This study evaluated simulated hearing loss on performance and cognitive workload among Army aviators. A mixed-effects linear regression study design was used. A total of 21 aviators underwent clinical audiological testing and simulated flight performance assessments. Simulated hearing loss and workload were manipulated to investigate their effects on speech recognition, flight performance, and subjective workload. Flight simulator routes included normal hearing and simulated hearing loss conditions for both high and low workloads. Task load questionnaires were administered for subjective workload assessments and compared across conditions. Speech recognition scores decreased with increasing levels of hearing loss. In-flight speech intelligibility declined in high workload conditions, with a 26% decrease for mild hearing loss and a 40% decrease for severe hearing loss. High workload conditions degraded flight performance and response times to a secondary task which was exacerbated by simulated hearing loss. Workload scores validated increased workload with simulated hearing loss. No significant findings were observed on the hearing assessment. Findings suggest hearing loss negatively impacts speech recognition and flight performance, especially under high workloads. These results support the importance of addressing hearing loss in aviators. Further research is needed to determine if the clinically adapted Modified Rhyme Test can reflect the impact of hearing loss on aviator performance. Noetzel J, Henry P, Mackie R, Cave K, Stefanson JR, Hale JK, Andres K, Jones H. Simulated hearing loss on speech recognition, flight performance, and workload in aviators. Aerosp Med Hum Perform. 2025; 96(4):269-278.

Abstract Background: Cognitive workload (CWL), a crucial concept in aviation human factors, has been described as the interplay between the aviator’s multidimensional, limited cognitive resources and the simultaneous dynamic task demands. The literature reports three general approaches to measuring CWL, task performance metrics, psychophysiological biomarkers, and relatively standardized CWL self-report ratings. The present study assesses a fourth method adapted from standard classic sensory psychophysics. Methods: Subjects were three study-team members highly trained on a surrogate aviation task. Random sequences of 10 CWL task demand levels (DL) spanning the range from low to high were presented to each subject. Using a 2-alternative forced-choice (2AFC) psychophysical thresholding paradigm, the minimum difference in DL a subject could reliably discriminate was measured at each DL. This method of measuring CWL DL differences is analogous to a psychophysical measurement of just noticeable sensory differences (JND). Results: Unexpectedly, the JND size for high-to-low DL transitions was much smaller than that of low-to-high DL transitions. Conclusions: The study demonstrated the feasibility of adapting a quantitative sensory psychophysical testing paradigm to develop an analogous psychophysics of CWL. The results identified an unexpected difference in CWL JND size that depends on the direction of transition. This difference suggests that the CWL demand experienced at a given demand level may depend on whether the demand level was approached from a lower or higher direction. This difference may have practical implications for implementing dynamic adaptive automation. These results support the value of further studies to elaborate the concept of a CWL psychophysics.

The U.S. Army Aeromedical Research Laboratory (USAARL), a partner in the Joint Trauma Analysis for the Prevention of Injury in Combat (JTAPIC) partnership, conducted a series of retrospective reviews to investigate injuries sustained by occupants of U.S. Army rotary-wing aircraft involved in combat damage incidents. The reviews were conducted to provide occupant survivability information to the Aviation Survivability Development and Tactics team, an agency within the U.S. Army Aviation Center of Excellence. For these reviews, combat damage incidents that produced casualties were separated into direct events (i.e., events in which an enemy weapon system directly injured occupants) and indirect events (i.e., incidents in which occupants were injured as a result of a crash caused by the enemy weapon system). The previous USAARL reviews provided an overview of injuries sustained during direct and indirect events. The objective of this review was to conduct a detailed analysis of injuries occurring during direct events. A descriptive retrospective review was conducted on injuries sustained by occupants of U.S. Army rotary-wing aircraft involved in combat damage incidents between 2003 and 2014. All Black Hawk, Apache, and Chinook combat aviation damage incidents for the study period were reviewed. Personnel casualty information from the Defense Casualty Information Processing System (DCIPS) was linked to combat damage incident information by matching the aircraft platform, incident date, and circumstantial information found in incident narratives. Injury information for personnel identified in DCIPS as being wounded in action was obtained from the JTAPIC partnership; injury data for personnel killed in action were retrieved from the Armed Forces Medical Examiner System. All injuries were coded using the Abbreviated Injury Scale (AIS). Descriptive statistics were used to describe the frequency and distribution of injuries to personnel involved in direct events. Overall, the extremities were the most commonly injured body regions, with lower extremities suffering more injuries than upper extremities. Penetrating injuries were identified as the primary injury mechanism for all body regions. Injuries to each AIS body region were predominantly of minor (AIS 1) and moderate (AIS 2) severity. Although injury severities were generally low (AIS 1 or AIS 2), the results of this effort indicate which body regions may benefit from additional protection during rotary-wing operations in hostile environments. The influence of occupant position within the aircraft and the use and effectiveness of personal protective equipment could not be effectively analyzed due to a lack of information.

Aim & Research QuestionThis study used accurate head impact monitoring mouthguard data, video review of visible concussion signs (VS), and a validated brain injury model to predict areas of the brain most affected by a head impact. The research question was whether brain simulation magnitude and location of highest strain would correlate to clinical concussion signs observed on video.DesignRetrospective Observational.Cohort/SettingMilitary service members in training and athletics, as well as civilian athletes.ParticipantsN=973.Independent VariablesVideo review of VS by an expert rater.Outcome MeasuresVS of concussion based on Davis et al. (2019), accurate impact monitoring mouthguard data, brain strain magnitude from a validated computational model.Main Results54,602 impacts across 3449 subject-days of participation were collected. VS were seen in n=57 impacts (0.1%). All VS impacts were in the top 1% by magnitude. The maximum strain location in the brain correlated to VS in 71% of cases. No VS impacts, including impacts with loss of consciousness, had strain levels larger than critical levels from Takhounts et al. (2008).ConclusionsImpacts with VS of concussion had significantly greater measured force than those without. The computational model results had good correlation with the likely VS region of the brain that was affected in the impact. The previous brain model strain limits may need to be re-examined to correlate more closely with VS seen in the real-world.

Abstract This work presents some of the challenges and solutions identified when using a historical collection of high-speed film from human research volunteer and anthropomorphic test device sled tests to define corridors for head flail kinematics. Challenges were related to film “jitter” and a lack of information about timing, test setups, and camera position. The challenges were addressed for a set of 939 tests using digitized high-speed film and minimal additional information for calculating head displacement, scaling, and translating to the seat origin. The method produced realistic head displacement data from tracked phototarget data. For the scaling method, the expanded uncertainty of measuring the phototarget size ranged from ±2.6 to ±3.7 pixels at a 95% confidence level. For the seat origin translation method, the average difference between calculated and actual seat origins was 6.6±5.0 cm. The methods implemented in this work can inform future work leveraging tracked kinematic data from this and other historical biodynamics datasets, especially large datasets that require batch processing.

Wearable devices are increasingly used to measure real-world head impacts and study brain injury mechanisms. These devices must undergo validation testing to ensure they provide reliable and accurate information for head impact sensing, and controlled laboratory testing should be the first step of validation. Past validation studies have applied varying methodologies, and some devices have been deployed for on-field use without validation. This paper presents best practices recommendations for validating wearable head kinematic devices in the laboratory, with the goal of standardizing validation test methods and data reporting. Key considerations, recommended approaches, and specific considerations were developed for four main aspects of laboratory validation, including surrogate selection, test conditions, data collection, and data analysis. Recommendations were generated by a group with expertise in head kinematic sensing and laboratory validation methods and reviewed by a larger group to achieve consensus on best practices. We recommend that these best practices are followed by manufacturers, users, and reviewers to conduct and/or review laboratory validation of wearable devices, which is a minimum initial step prior to on-field validation and deployment. We anticipate that the best practices recommendations will lead to more rigorous validation of wearable head kinematic devices and higher accuracy in head impact data, which can subsequently advance brain injury research and management.

Background: Ulnar collateral ligament (UCL) tears in the throwing elbow are classified according to grade and location using magnetic resonance arthrography (MRA). However, the frequency of each tear type and the association to age, competition level, and radiographic findings in adolescent baseball pitchers are unknown. Purposes: The primary purpose of this study was to use MRA to characterize the severity, location, and UCL tear type in adolescent pitchers. The second aim was to describe the relationship between the UCL tear type and age, competition level, and plain radiographic findings. Study Design: Cross-sectional study; Level of evidence, 3. Methods: Records of adolescent pitchers with a UCL tear treated by the senior author between 2007 and 2016 were retrospectively reviewed. MRA scans were reviewed and tears were classified according to the Joyner-Andrews classification. Low-grade partial tears are classified as type I, high-grade partial tears as type II, complete full-thickness tears as type III, and tear pathology in >1 region in the UCL as type IV. Each type of tear also has a location designated at the midsubstance, ulna (U), or humerus (H). Patient characteristics, competition level, and associated plain radiographic abnormalities were recorded. Univariate analyses were performed to examine the relationships between tear types and age, competition level, and plain radiographic findings. Results: A total of 200 adolescent pitchers (mean ± SD age, 17.2 ± 1.5 years) with MRA scans were reviewed. Type II-H (n = 62), type II-U (n = 51), and type III-U (n = 28) were the most common tear types observed. Type II tears comprised 64.5% of adolescent UCL tears, with type II-H being the most common. Plain radiographs were abnormal in 32% of patients, with calcifications (10.5%) and olecranon osteophytes (12.5%) being the most common findings. There were no significant relationships between tear type and age (P = .25), competition level (P = .23), or radiographic abnormalities (P = .75). Conclusion: Humeral-sided high-grade partial tears were the most common tear type in adolescent pitchers. There was no relationship between UCL tear type and age competition level, and plain radiographic abnormalities.