High Task Load Research Articles

Effects of the Interaction Between Time-on-Task and Task Load on Response Lapses.

To investigate the interaction effects of prolonged working periods and different task loads on response lapses, focusing on the mechanisms of delayed responses and error lapses. Professionals such as pilots, truck drivers, and nurses often face extended work hours and fluctuating task loads. While these factors individually affect performance, their interaction and its impact on response lapses remain unclear. Twenty participants completed the Uchida-Kraepelin (U-K) Psychological Test and a dual-task version with functional near-infrared spectroscopy. Independent variables were time-on-task and task load. Dependent variables included measures of fatigue, arousal, workload, task performance (delayed and error rates), and brain functional connectivity. Both time-on-task and task load significantly affected cerebral connectivity, response lapses, workload (frustration level), fatigue, and arousal. Arousal levels significantly decreased and reaction times increased after 60 min of work. Cognitive resource regulation became challenging after 90 min under high task load levels. A decline in the connection between the prefrontal and occipital cortex during high-load tasks was observed. The findings provide insight into the mechanisms of response lapses under different task load levels and can inform strategies to mitigate these lapses during extended work periods. This study's findings can be applied to improve work schedules and fatigue management in industries like aviation, transportation, and healthcare, helping reduce response lapses and errors during extended work periods under high task load conditions.

Abdominal Drawing-In Maneuver is Less Effective for Core Stability During High Load Tasks: A Systematic Review

Context: The abdominal drawing-in maneuver (ADIM) is a technique commonly used to activate deep core muscles for the prevention and rehabilitation of low back pain. However, its benefits during high-load tasks (HLT) are unclear. Objectives: The primary objective of this article is to review the literature to determine whether the use of ADIM enhances core stabilization during HLT. Additionally, we will examine if other factors, beyond load, could influence the effectiveness of this activation maneuver. Methods: A search was conducted using PubMed databases for studies that compared interventions using ADIM to those without ADIM. The literature search spanned from January 1981 to March 2024. Only studies that included kinematic assessments were selected. Results: The search yielded 359 studies, of which 24 were included in the final analysis. Task load was analyzed based on Mottram and Comerford's criteria, alongside other approaches such as the source of the perturbation applied to the subject and body position. In conditions using ADIM, better performance was observed in only 16.66% of interventions with HLT, whereas other conditions (OC) without ADIM performed better in 83.33% of interventions using HLT. When core stability was tested against external perturbations, ADIM was less effective in all scenarios. In lying positions, ADIM performed better in 4 tasks, while OC performed better in 2. In upright positions, ADIM was more effective in 7 tasks, while OC performed better in 6. Conclusions: The findings suggest that ADIM should not be used if the goal is to train core stability and strength during HLT. Abdominal drawing-in maneuver was less effective for stabilizing the core during tasks involving external perturbations, and its use was also less decisive in upright positions.

Analysis and Simulation of Permanent Magnet Adsorption Performance of Wall-Climbing Robot

In response to problems such as insufficient adhesion, difficulty in adjustment, and weak obstacle-crossing capabilities in traditional robots, an innovative design has been developed for a five-wheeled climbing robot equipped with a pendulum-style magnetic control adsorption module. This design effectively reduces the weight of the robot, and sensors on the magnetic adsorption module enable real-time monitoring of magnetic force. Intelligent control adjusts the pendulum angle to modify the magnetic force according to different wall conditions. The magnetic adsorption module, using a Halbach array, enhances the concentration effect of the magnetic field, ensuring excellent performance in high-load tasks such as building maintenance, bridge inspection, and ship cleaning. The five-wheel structural design enhances the stability and obstacle-crossing capability, making it suitable for all-terrain environments. Simulation experiments using Maxwell analyzed the effects of the magnetic gap and the angle between the adsorption module and the wall, and mechanical performance analysis confirmed the robot’s ability to adhere safely and operate stably.

Design and research on sequentially controlled magnetic-driven actuators with high stiffness by changing local EGaIn structural density

Magnetic-driven actuators (MDAs) are attracting increasing attention due to fast response and harmless interaction with humans. However, due to their low stiffness and difficulties in sequential magnetic control, MDAs are difficult to complete high-load tasks, and overcoming these obstacles can enable them to be exploited for a wide range of novel applications. In this work, sequentially controlled MDAs (SC-MDAs) with high stiffness were prepared by embedding a polydimethylsiloxane/liquid metal (PDMS/EGaIn) heating layer between magnetic memory polymer (MSMP) films. The variation of EGaIn structural density between different regions leads to temperature discrepancies, resulting in selective activation of specific regions for sequence control. The modulus of the optimized MSMP film at room temperature is 2.21 GPa, which exceeds that of other materials (about 1 MPa) by three orders of magnitude, demonstrating a substantial increase in stiffness. When the content of NdFeB is adjusted to 80 wt%, driving performance is adjusted by optimizing the length-thickness ratio of SC-MDAs. Each claw of the mechanical gripper exhibits a remarkable increase in load capacity, being able to carry 54 times its own weight, which is significantly higher compared to actuators made from other materials (about its weight). A hand-like actuator realizes the sequential control deformation by combining “fingers” with different heating properties.

The effect of reward expectation on working memory of emotional faces under different levels of cognitive load: an ERP study.

Using event-related potentials (ERPs), this study examined the impact of reward expectations on working memory of emotional faces under different levels of cognitive load in a task combining the N-back paradigm and the reward expectation paradigm. The experiment involved presenting high- or low-reward cues followed by an N-back task for emotional faces with different loads. The accuracy results showed that under a high task load, both reward and emotion effects were significantly observed. However, these effects disappeared under a low task load. Analysis of the ERP data revealed that the early P2 and VPP components exhibited greater responses to fearful faces than to neutral faces. In the later stages, the P3 and LPP components showed greater reactions to high rewards than to low rewards. Additionally, the P2 component was found to be modulated by task load in relation to rewards, the EPN component demonstrated task load modulation with respect to emotions, and the N170 component showed an interaction effect between rewards and emotions. These findings imply that load regulates the reward effect and the emotional superiority effect in the process of working memory for emotional faces. In the cognitive processing of working memory, motivation and emotion jointly influence processing. Emotional factors have a greater impact in the early stage of processing, while motivation factors have a greater impact in the late stage of processing.

The effect of emotional motivation on strategy flexibility: the moderating role of task load

IntroductionResearch has demonstrated that cognitive flexibility is associated with academic achievement, with poorer cognitive flexibility being linked to poorer academic performance. Strategy conversion is an example of cognitive flexibility, which requires individuals to quickly and flexibly switch between strategies depending on the task at hand. Studies have investigated the impact of emotional motivation on cognitive flexibility, with varying results. Furthermore, research has indicated that a high task load increases psychological burden and reduces cognitive flexibility, but few studies have analyzed the impact of task load on the relationship between emotional motivation and cognitive flexibility. This study sought to investigate the effect of emotional motivation on cognitive flexibility based on strategy switching, and the moderating effect of task load.MethodsThree experiments were conducted. Experiment 1 used forced conversion paradigm with a moderate task load that required participants to estimate tasks using a given strategy. Experiment 2 employed matched conversion paradigm with a high task load, informing participants of the strategies to be used but without any clues, necessitating the selection and execution of appropriate strategies based on the question features. Experiment 3 adopted free conversion paradigm with a relatively low task load, allowing participants to freely choose and execute strategies without any correctness or error criteria.ResultsThe intensity and direction of emotional motivation have a complicated and fluctuating impact on the flexibility to utilize strategies. When the task workload is high, the intensity of emotional motivation has a significant impact on strategy utilization flexibility, with low approach motivation being more conducive to flexibility. Conversely, when the task workload is low, the direction of emotional motivation has a greater effect, with high avoidance motivation being more advantageous.DiscussionThis study demonstrated that high workload could bring about a low intensity advantage, while low workload could induce an avoidance direction advantage, suggesting that task load could moderate the impact of emotional motivation on arithmetic strategy utilization flexibility, and avoidance motivation is not always detrimental to cognitive flexibility.

The Influence of Probe Frequency on Self-Reported Mind Wandering During Tasks With Different Cognitive Loads.

The use of thought-probe methodologies during tasks with varying loads has become commonplace. The current study aimed to investigate whether there exists an interaction between probe frequency and task load on responses of mind wandering episodes, using within-subject designs. In Experiment 1, We performed 0-back, 1-back, and 3-back tasks, in which low-frequency and high-frequency thought probes were presented to the participants. The results indicated that fewer probes led to more reported mind wandering episodes during 0-back and 1-back tasks. Conversely, a significant increase in mind wandering was observed in the 3-back task when higher-frequency probes were used. Experiment 2 introduced the probe relatedness dimension to the medium- and high-load tasks. Both experiments demonstrated that increasing probe frequency reduced mind wandering during the low- and medium-load tasks, but increased it during the high-load task. Additionally, Experiment 2 revealed that higher probe frequency resulted in more probe-related mind wandering during the high-load task, but not during the medium-load task. The current findings reveal the interaction effect of probe frequency and task load on mind wandering and offer possible explanations.

Contributions of Tasks With Different Cognitive Load to High School Students’ In-Class Physical Activity

Purpose: Cognitive load theory focuses on providing appropriate cognitive engagement to facilitate knowledge learning. The purpose of this study was to determine the contributions of cognitive load on high school students’ in-class physical activity. Method: A stratified random sample of high school students (N = 150) who participated in a large curriculum intervention study provided the data. A path analysis and Hayes’ PROCESS analysis were used to test a correlation model and moderation effect from gender and race. Results: The results showed that the reasoning learning tasks directly contributed to their in-class physical activity (path coefficient = .54, p < .01) and the gender and race factors were not significant moderators (p > .05). Conclusion: The findings imply that high cognitive load tasks can facilitate in-class physical activity. The findings suggest the power of the concept-based physical education curriculum in providing productive learning opportunities to all students.

The role of focus back effort in the relationships among motivation, interest, and mind wandering: an individual difference perspective

Considerable research suggests a link between mind wandering and diminished levels of motivation and interest. During episodes of mind wandering, individuals may engage in efforts to redirect their attention back to the task at hand (known as focus back effort). Building on the resource-control hypothesis, we hypothesized that the influence of interest and motivation on mind wandering may be mediated by focus back effort. In Study 1, we employed a latent-variable approach to investigate these relationships across three tasks with varying cognitive demands. The results showed that individual differences in interest indirectly influenced mind wandering through the mediating factors of motivation and focus back effort. Furthermore, individual differences in interest indirectly predicted task performance through the mediating factors of motivation, focus back effort, and mind wandering during the high-load task. In Study 2, we replicated the relationships among these factors in a reading comprehension task. The results consistently support the role of focus back effort as an adaptive mechanism for executive control, enabling the allocation of cognitive resources to both mind wandering and task performance. These findings underscore the significance of focus back effort in elucidating the interplay between mind wandering, motivation, interest, and task performance. Importantly, our results align with the resource-control theory.

Development and validation of an assessment index for quantifying cognitive task load in pilots under simulated flight conditions using heart rate variability and principal component analysis

To investigate whether high cognitive task load (CTL) for aircraft pilots can be identified by analysing heart-rate variability, electrocardiograms were recorded while cadet pilots (n = 68) performed the plane tracking, anti-gravity pedalling, and reaction tasks during simulated flight missions. Data for standard electrocardiogram parameters were extracted from the R–R-interval series. In the research phase, low frequency power (LF), high frequency power (HF), normalised HF, and LF/HF differed significantly between high and low CTL conditions (p < .05 for all). A principal component analysis identified three components contributing 90.62% of cumulative heart-rate variance. These principal components were incorporated into a composite index. Validation in a separate group of cadet pilots (n = 139) under similar conditions showed that the index value significantly increased with increasing CTL (p < .05). The heart-rate variability index can be used to objectively identify high CTL flight conditions. Practitioner summary: We used principal component analysis of electrocardiogram data to construct a composite index for identifying high cognitive task load in pilots during simulated flight. We validated the index in a separate group of pilots under similar conditions. The index can be used to improve cadet training and flight safety. Abbreviations: ANOVA: a one-way analysis of variance; AP: anti-gravity pedaling task; CTL: cognitive task load; ECG: electrocardiograms; HR: heart rate; HRV: heart-rate variability; HRVI: heart-rate variability index; PT: plane-tracking task; RMSSD: root-mean square of differences between consecutive R–R intervals; RT: reaction task; SDNN: standard deviation of R-R intervals; HF: high frequency power; HFnu: normalized HF; LF: low frequency power; LFnu: normalized LF; PCA: principal component analysis.

L2 writing anxiety, working memory, and task complexity in L2 written performance

Building on the Attentional Control Theory proposed by Eysenck et al. (2007), this study aims to investigate the potential effect of L2 writing anxiety on the syntactic complexity of English learners' written texts by accounting for working memory as a potential mediator, while also examining the impact of L2 writing anxiety on learner texts’ syntactic complexity under high and low cognitive demands, and testing whether syntactic complexity is reduced in written texts produced under high cognitive demand. The participants were 126 learners of English as a Foreign Language, divided into low and high-writing anxiety groups while their reading anxiety, working memory capacity, and previous writing scores were kept equal. Each participant completed two integrated L2 writing tasks with varying cognitive loads. Empirical findings of this study show that high L2 writing anxiety may play a suppressive role on learners' working memory, thereby resulting in reduced syntactic complexity in written texts produced. Furthermore, consistent with previous research, this study documents the negative impact of L2 writing anxiety and highlights the influence of high cognitive load tasks on L2 learners' syntactic complexity in text production.

Investigating the effects of age, task load, task complexity, and input device on monitoring performance for smart manufacturing in the oil refining industry

Human beings play an important role in a smart manufacturing economy. In this study, we explored the effects of age, task load, task complexity, and input device on abnormal event detection performance in an oil refinery control room task. Thirty participants were recruited to complete a process plant monitoring task in which they were asked to continuously monitor the gauge states, and immediately detect and solve the abnormal events. Participants’ accuracy in detecting abnormal states was recorded and analysed during the task. We found that the complexity factor affected accuracy significantly, and younger adults had significantly higher accuracy than older adults in high task load trials. No significant effect was found for the input device factor. These findings suggest that age, task load, and task complexity should be taken into consideration when designing tools to improve older operators’ performance. Practitioner summary: The smart manufacturing economy elicits higher requirements for older operators in oil refinery monitoring tasks. Under high task load, older adults had lower accuracy in detecting abnormal conditions than younger adults. The task complexity affected participants’ accuracy in detecting abnormal states.

Prefrontal oxygenation and working memory in patients with type 2 diabetes mellitus following integrated yoga: a randomized controlled trial.

Type 2 diabetes mellitus (T2DM) alters brain functional and structural connectivity leading to cognitive dysfunction. This study examined the effect of a 12-week yoga intervention on prefrontal cortex (PFC) oxygenation and working memory in patients with T2DM. Fifty participants were randomized into yoga and waitlist control groups. The yoga protocol specific to T2DM was followed. The pre- (day 1), mid- (6weeks) and post-intervention (12weeks) assessments included measurement of PFC oxygenation while performing working memory tasks (n-back) using functional near-infrared spectroscopy. Following a 12-week intervention, the yoga group showed improved performance in working memory [accuracy (geometric mean difference of 3.15%, 95% CI [2.33,3.96], p = 0.001) and reaction time (mean difference of 100.8 milliseconds,95% CI [- 166.6, - 35.1], p = 0.002] in the high task load (2-back) associated with higher oxygenation in dorsolateral PFC (β coefficient mean difference of 95.6, 95% CI [0.23,191], p = 0.049) and ventrolateral PFC (β coefficient mean difference of 53.4, 95% CI [7.8,98.9], p = 0.018) regions. Higher oxygenation in dorsolateral PFC during 2-back task was positively correlated with accuracy (r(23) = 0.65, p < 0.001) and negatively correlated with reaction time (r(23) = - 0.47,p = 0.017). Integrated yoga practice may improve working memory performance associated with higher PFC oxygenation in patients with T2DM. As 12weeks of yoga intervention improved working memory performance, the regular practice of yoga may have the potential to prevent decline of cognitive functions in clinical conditions.

Transcutaneous auricular vagus stimulation (taVNS) improves human working memory performance under sleep deprivation stress

Many human activities require high cognitive performance over long periods, while impairments induced by sleep deprivation influence various aspects of cognitive abilities, including working memory (WM), attention, and processing speed. Based on previous research, vagal nerve stimulation can modulate cognitive abilities, attention, and arousal. Two experiments were conducted to assess the efficacy of transcutaneous auricular vagus nerve stimulation (taVNS) to relieve the deleterious effects of sleep deprivation. In the first experiment, 35 participants completed N-back tasks at 8:00 a.m. for two consecutive days in a within-subject study. Then, the participants received either taVNS or earlobe stimulation (active control) intervention in two sessions at random orders after 24 h of sustained wakefulness. Then, they completed the N-back tasks again. In the second experiment, 30 participants completed the psychomotor vigilance task (PVT), and 32 completed the N-back tasks at 8:00 a.m. on the first and second days. Then, they received either taVNS or earlobe stimulation at random orders and finished the N-back and PVT tasks immediately after one hour. In Experiment 1, taVNS could significantly improve the accuracy rate of participants in spatial 3-back tasks compared to active control, which was consistent with experiment 2. However, taVNS did not specifically enhance PVT performance. Therefore, taVNS could be a powerful intervention for acute sleep deprivation as it can improve performance on high cognitive load tasks and is easy to administer.

The aftermath of surviving a sudden cardiac arrest for young exercisers - a qualitative study in Norway

BackgroundWhen surviving a sudden cardiac arrest (SCA), physical, cognitive, and emotional effects of surviving may be present for months or years. The survivors' family and colleagues are also highly affected by the incident. There is little knowledge about experiences of surviving SCA in individuals who prior to the incident were young and reported to exercise regularly. Consequently, the aim of this study was to explore the aftermath of surviving a SCA in young, regular exercisers.MethodsThe study had a qualitative design, conducting in-depth individual interviews with SCA survivors < 50 years of age reporting to exercise ≥ 5 h/week and/or who suffered SCA during or less than 60 min after exercise. The data were analysed using systematic text condensation in-line with recommendations from Malterud.Results18 of 31 eligible participants were included in the study. Through analysis we identified ‘Establishing a new everyday life’ as superordinate category, with subordinate categories a) being part of my surroundings, b) expecting normality but facing a new reality and c) lucky to be alive!ConclusionThis study adds knowledge about young and regular exercisers’ experiences after surviving a SCA. The obligations of everyday life in young survivors of SCA often imply a high work load and complex tasks, e.g. due to being in the beginning of their career or even still studying. Healthcare personnel, as well as the society, need to acknowledge that although lucky to be alive and apparently well-functioning, young survivors of SCA may have persistent challenges that cause frustration and reduced quality of life.

Social threat and safety learning in individuals with adverse childhood experiences: electrocortical evidence on face processing, recognition, and working memory

ABSTRACT Background: Adverse childhood experiences (ACEs) are often associated with stress and anxiety-related disorders in adulthood, and learning and memory deficits have been suggested as a potential link between ACEs and psychopathology. Objective: In this preregistered study, the impact of social threat learning on the processing, encoding, and recognition of unknown faces as well as their contextual settings was measured by recognition performance and event-related brain potentials. Method: Sixty-four individuals with ACEs encoded neutral faces within threatening or safe context conditions. During recognition, participants had to decide whether a face was new or had been previously presented in what context (item-source memory), looking at old and new faces. For visual working memory, participants had to detect changes in low and high load conditions during contextual threat or safety. Results: Results showed a successful induction of threat expectation in persons with ACEs. In terms of face and source recognition, overall recognition of safe and new faces was better compared to threatening face-compounds, with more socially anxious individuals having an advantage in remembering threatening faces. For working memory, an effect of task load was found on performance, irrespective of threat or safety context. Regarding electrocortical activity, an old/new recognition effect and threat-selective processing of face–context information was observed during both encoding and recognition. Moreover, neural activity associated with change detection was found for faces in a threatening context, but only at high task load, suggesting reduced capacity for faces in potentially harmful situations when cognitive resources are limited. Conclusion: While individuals with ACE showed intact social threat and safety learning overall, threat-selective face processing was observed for item/source memory, and a threatening context required more processing resources for visual working memory. Further research is needed to investigate the psychophysiological processes involved in functional and dysfunctional memory systems and their importance as vulnerability factors for stress-related disorders.

Heart rate variability, task load and perceived exertion associated with a long-distance military ski exercise: A pilot study

Objectives: Skiing is practiced by the security forces posted at mountain areas for patrolling, securing borders, taking up rescue missions and sometimes as recreational activities. A study was planned to assess physiological and mental stress of a military ski activity through the measurement of heart rate (HR) variability, task load and perceived exertion. Materials and Methods: Eleven healthy Indian soldiers, trained with skiing techniques, participated in a 15 km skiing with 22 kg equipment at a predetermined snowy mountainous track. Pre- and post-exercise HR and HR variability (HRV) were recorded (bio-harness, Zephyr, USA) and questionnaires, namely NASA task load index (NASA-TLX) and Borg’s rating of perceived exertion (RPE) scale, were filled after exercise. Time and frequency domain parameters such as HR, variations between successive RR intervals (RMSSD), standard deviation of RR (SDNN) and percentage value of NN50 (pNN50), low- and high-frequency bands (LF and HF %) and LF/HF ratio were derived using Kubios software. Student’s t (paired) test was applied to compare pre- and post-exercise HRV parameters and Pearson’s correlation was applied to observe interdependencies between HRV and subjective scores. Results: The findings depicted increase in post-exercise HR and decrease in overall HRV (both significant). Besides this, there was an increase in LF (significant) and LF/HF ratio (insignificant). Such response shows sympathetic dominance over parasympathetic domain of autonomic nervous system. The physical and mental stress experienced during the exercise was also expressed through high physical demand (79 out of 100) and high overall task load (total score – 77 out of 100) of the NASA-TLX and a moderately heavy RPE score (14 out of 20). Conclusion: The pre- and post-exercise differences in physiological variables ensured the presence of physical stress along with dominance of sympathetic nervous system. Overall task load was depicted with high subjective ratings. Carrying out skiing task in an environment infested with cold, wind chill, moderate hypoxia at a snowy and mountainous track possibly has induced the observed physiological and mental stress to the participants. Such findings are important to understand exact requirements of the mountain warfare events carried out by the forces.

Concurrent working memory task increases or decreases the flanker-related N2 amplitude.

Concurrent working memory (WM) task reduces available attentional control resources to perform the flanker task. However, controversy exists as to whether concurrent WM task increases or decreases flanker-related N2 amplitude. In a flanker task experiment, individuals were confronted with a low, middle, or high WM load task, while electroencephalography (EEG) data were recorded. The ERP results showed a larger flanker-related N2 amplitude while completing a middle or high WM load task compared to a low one. However, completing an additional high WM load task could not increase flanker-related N2 amplitude versus completing an additional middle WM load task. In sum, these results suggest that WM load can impair top-down cognitive control processes, thereby hampering flanker task performance. Importantly, the present study supports the account of flanker-related N2 processes linked to top-down attentional control resource allocation, but challenges the account of flanker-related N2 reflecting response conflict processes.

Intermuscular Coherence Of Rotator Cuff And Deltoid Muscles Varies With Force Output

PURPOSE:To identify intermuscular EMG coherence patterns between the rotator cuff and deltoid muscles at different force levels. METHODS:Surface EMG electrodes were used to record activity from the anterior deltoid (AD), middle deltoid (MD), and infraspinatus (IS) muscles of the dominant shoulder in 7 healthy individuals (mean age ± SD = 19 ± 1, 6 females, 1 male). An intramuscular fine-wire EMG electrode was inserted into supraspinatus (SS). Participants performed 30s contractions of isometric shoulder abduction in the scapular plane at 30° at 25% (low-load), 50% (medium-load) and 75% (high-load) of maximum voluntary contraction with visual feedback of the force output. EMG amplitudes and coherence of each muscle pair in the common drive (0-5 Hz), physiological force tremor (5-12 Hz), beta (15-35 Hz), low-gamma (35-60 Hz) and high-gamma (60-100 Hz) bands were compared across the 3 force levels. RESULTS:EMG amplitudes of all muscles increased as force level increased (all p < 0.05). EMG coherence between IS and deltoid muscles increased as force level increased in the low-gamma band (p < 0.05). SS-IS coherence was also the highest during high-load task in the low-gamma band. These data indicate that additional neural drive with higher force levels stemming from subcortical origin likely mediate the increase in coherence between these muscles. However, SS-IS coherence during the medium and high load tasks were lower than that during the low-load task in the common drive band (p < 0.05), indicating that the increase in drive to these muscles for increasing force output is not targeted at common last-order neurons. Similarly, SS-AD coherence during the high-load task was lower than that during the medium-load task in the beta band (p < 0.05) and SS-AD and SS-MD was lower in the tremor band (p < 0.05) at higher force loads. The reduction in coherence between the SS and deltoid muscles and the SS and IS may serve to protect the humeral head from migrating superiorly at higher force loads. CONCLUSIONS:Increasing force output led to decreased coherence within the rotator cuff muscles and between supraspinatus and the deltoid muscles, but increased coherence between infraspinatus and the deltoid muscles. This likely serves as a protective mechanism against superior humeral head migration.

Simulated Space Radiation Exposure Effects on Switch Task Performance in Rats.

BACKGROUND: Astronauts on the mission to Mars will be subjected to galactic cosmic radiation (GCR) exposures. While ground-based studies suggest that simulated GCR (GCRsim) exposure impairs performance in multiple cognitive tasks, the impact of such exposures on task switching performance (an important skill for all aviators) has not yet been determined.METHODS: Male Wistar rats previously exposed to 10 cGy of ⁴He ions or GCRsim and their sham littermates were trained to perform a touchscreen-based switch task designed to mimic warning light response tests used to evaluate pilots' response times.RESULTS: Irradiated rats failed to complete a high cognitive task load training task threefold more frequently than shams. There were 18 (4 Sham, 7 He-, and 7 GCR-exposed) rats that successfully completed initial training and underwent switch task testing. Relative to the sham rats in the switch task, the GCRsim-exposed rats had significantly slower response times in switch but not repeat trials. The GCRsim-exposed rats had significantly (P < 0.01) higher switch response ratios (switch/repeat trial response time) and absolute switch costs (switch minus repeat trial response time) than either the sham or He-exposed rats.DISCUSSION: Rats exposed to GCRsim have significantly impaired performance in the switch task manifested as an absolute switch cost of ∼700 ms. The operational significance of such an increase requires further investigation, but a 1000-ms switch cost results in a twofold increase in cockpit error rates in pilots. If exposure to GCR in space results in similar effects in humans, the operational performance of astronauts on the Mars mission may be suboptimal.Stephenson S, Britten R. Simulated space radiation exposure effects on switch task performance in rats. Aerosp Med Hum Perform. 2022; 93(9):673-680.