Workload Ratings Research Articles

Workload assessment: Time to emanate from accurate conclusions instead of preconceived notions

AbstractTraditionally, assessments in psychosocial work environment research and practice utilize unidimensional response formats. This presupposes that higher or lower values are better or worse. Using unidimensional questions to assess multidimensional variables such as workload can be misleading. Two‐dimensional assessments using completing questions that indicate different aspects of the same construct may increase assessment precision and correctness. The current study aims to elucidate if and how two‐dimensional assessments of workload, that is, consistent ratings of high or low workload and level of satisfaction with it in repeated assessments, are related to outcomes in indicators of health, stress, well‐being and the psychosocial work environment, both cross‐sectionally and over time. 1284 study participants were followed for over 2 years. The results clearly and systematically demonstrated that often or rarely having too much to do, is not a reliable nor valid indicator of health, stress, well‐being and psychosocial work environment‐related outcomes. In contrast, the satisfaction dimension is systematically and consistently related to statistically significant and more pronounced differences in these outcomes. To properly help individuals at risk, both aspects of workload need to be assessed and accounted for. Whereas satisfaction is a better indicator of outcomes, the perceived workload magnitude is needed to intervene properly.

Using pupillometry and gaze-based metrics for understanding drivers’ mental workload during automated driving

This Horizon2020-funded driving simulator-based study on automated driving investigated the effect of different car-following scenarios, and takeover situations, on drivers’ mental workload, as measured by eye tracking-based metrics of pupil diameter and self-reported workload ratings. This study incorporated a mixed design format, with 16 drivers recruited for the SAE Level 2 (L2; SAE International, 2021) automation group, who were asked to monitor the driving and road environment during automation, and 16 drivers in the Level 3 (L3) automation group, who engaged in a non-driving related task (NDRT; Arrows task) during automation. Drivers in each group undertook two experimental drives, lasting about 18 min each. To manipulate perceived workload, difficulty of the driving task was controlled by incorporating a lead vehicle which maintained either a Short (0.5 s) or Long (1.5 s) Time Headway (THW) condition during automated car-following (ACF). Each ACF session was followed by a subsequent request to takeover, which happened either in the presence or absence of a lead vehicle. Results from standard deviation of pupil diameter values indicated that drivers’ mental workload levels fluctuated significantly more when monitoring the drive during L2 ACF, compared to manual car-following (MCF). Additionally, we found that drivers’ mental workload, as indicated by their mean pupil diameter, increased steeply around takeovers, and was further exacerbated by the presence of a lead vehicle during the takeovers, especially in the Short THW condition, for both groups. Pupil diameter was found to be sensitive to subtle variations in mental workload, and closely resembled the trend seen in self-reported workload ratings. Further research is warranted to assess the feasibility of using eye-tracking-based metrics along with other physiological sensors, especially in real-world settings, to understand whether they can be used as real-time indicators of drivers’ mental workload, in future driver state monitoring systems.

Relationships between training load and wellbeing measures across a full season: a study of Turkish national youth wrestlers.

The two aims of this study were: (i) to analyse the correlations between weekly acute workload (wAW), chronic workload, acute/chronic workload rate (wACWR), training monotony and strain and the weekly (w) reports of delayed onset muscle soreness, wFatigue, wStress, wSleep quality, and the Hooper indicator (wHI); (ii) to analyse the relationships between early, mid and end preparation season (PS) and the full PS. Ten elite young wrestlers participated in this study. The subjects who were included in this research were wrestlers participating in competitions organized by the National Turkish Wrestling Federation. The subjects were monitored for 32 weeks and were divided into three time periods: early PS, W1 to W11; mid PS, W12 to W22; and end PS, W23 to W32. Very large correlations were found for wAW and wACWR with wFatigue and wHI during end PS. Also, the same workload parameters were significantly correlated with wStress (r = 0.66; P = 0.03), wSleep (r = 0.78; P = 0.004), and wHI (r = 0.72; P = 0.01) during mid PS. The results of this study offer new perspectives for specialists regarding the perceived level of load and the variations of wellbeing during a PS at the level of elite young wrestlers.

Effects of Reading Text on an Optical See-Through Head-Mounted Display During Treadmill Walking in a Virtual Environment

This study evaluated the effects of reading text on an optical see-through head-mounted display during treadmill walking in a virtual environment. Thirty participants were recruited to perform Chinese reading tasks by reading six types of text layouts in two polarity settings. A virtual environment was displayed on a projection screen to simulate a walking situation in which obstacles were encountered. High- and low-density obstacles were applied. Objective measures included reading performance, gait variability, and the error count of obstacles. The subjective measures were the situational awareness rating technique (SART) and NASA-Task Load Index (NASA-TLX) scores. The results indicated that font size and polarity affected the gait variability, reading performance, situational awareness, and mental workload ratings. The obstacle density affects gait variability and situation awareness rating. The layout with 32-point text and positive polarity yielded faster reading speed, better subjective ratings, and less variability in minimum foot clearance.

Evaluation of a Decision-Based Invocation Strategy for Adaptive Support for Air Traffic Control

Air traffic controller workload is a limiting factor in the current air traffic management system. Adaptive support systems have the potential to balance controller workload and gain acceptance as they provide support during times of need. Challenges in the design of adaptive support systems are to decide when and how to trigger support. The goal of this study is to gain empirical insights into these challenges through a human-in-the-loop experiment, featuring a simplified air traffic control environment in which a novel triggering mechanism uses the quality of the controller's decisions to determine when support is needed. The designed system seeks to prevent high workload conditions by providing resolution advisories when the controller exceeds a threshold of “self-complicating” decisions. Results indicate that the new system is indeed capable of increasing the efficiency and safety compared to full manual control without intervention. More adaptive support, however, increased the frustration of participants, decreased acceptance, and did not result in improved workload ratings. These findings suggest that, unless we can better infer human intent in complex work environments, adaptive support at the level of decision-making is problematic. A potentially more fruitful direction is to provide support at the level of information integration, with full decision-making authority with the human.

Predicting Human Reliability based on Individual’s Resting Period: Effect of Physical Workload Rate

When a person is exposed to a prolonged workload, he/she enters a fatigue phase, the indication is the decline of cognitive performance that leading to human error. As an integral part of a system, human contributes to system reliability; therefore, it plays an important role in potential failure. Those, it is necessary to investigate how human reliability relates to physical workload rate, in order to predict maximum work duration to eliminate potential failure. A physical experiment involving 20 participants was conducted to generate medium workload, followed by Stroop test to observe selective attention and cognitive control as a form of cognitive performance. The physical workload was observed through energy expenditure and oxygen consumption during physical activity, and cognitive performance through response error time on the Stroop test. The usage of Weibull distribution was aimed to obtain reliabilities for each participant. There was a decline in reliability for all participants from one test to the other. Based on scale and form parameters, the prediction of resting time was based on mean time to human error (MTTHE), and from this experiment, varied MTTHE from each participant were obtained. The variation was created by differences in physical performance, cognitive capabilities, and other contributing factors such as environment and time of the implementation of the experiment. From this research, it was evident that human reliability can be utilized to predict potential failure in humans, which then implies a preventive action is necessitated to prevent failure from manifesting in the shape of taking a break/rest or reducing work rhythm. The application of human reliability in human resource management can be directed towards fatigue management and operator-related operational management.

Sleep, Workload, and Stress in Aerial Firefighting Crews.

BACKGROUND:The challenges of climate change and increasing frequency of severe weather conditions has demanded innovative approaches to wildfire suppression. Australia's wildfire management includes an expanding aviation program, providing both fixed and rotary wing aerial platforms for reconnaissance, incident management, and quick response aerial fire suppression. These operations have typically been limited to day visual flight rules operations, but recently trials have been undertaken extending the window of operations into the night, with the assistance of night vision systems. Already a demanding job, night aerial firefighting operations have the potential to place even greater physical and mental demands on crewmembers. This study was designed to investigate sleep, fatigue, and performance outcomes in Australian aerial firefighting crews.METHODS:A total of nine subjects undertook a 21-d protocol, completing a sleep and duty diary including ratings of fatigue and workload. Salivary cortisol was collected daily, with additional samples provided before and after each flight, and heart rate variability was monitored during flight. Actigraphy was also used to objectively measure sleep during the data collection period.RESULTS:Descriptive findings suggest that subjects generally obtained >7 h sleep prior to flights, but cortisol levels and self-reported fatigue increased postflight. Furthermore, the greatest reported workload was associated with the domains of 'performance' and 'mental demand' during flights.DISCUSSION:Future research is necessary to understand the impact of active wildfire response on sleep, stress, and workload on aerial firefighting crews.Sprajcer M, Roberts S, Aisbett B, Ferguson S, Demasi D, Shriane A, Thomas MJW. Sleep, workload, and stress in aerial firefighting crews. Aerosp Med Hum Perform. 2022; 93(10):749-754.

The Value of Exercise Systolic Blood Pressure as an Indicator for Coronary Artery Disease in Normotensive Men

Abstract Aim: We investigated if rates of systolic blood pressure to workloads during exercise can independently predict coronary artery disease. Methods: 78 normotensive men with normal blood pressure who had exercise ECG stress test and a coronary angiography within 30 days were enrolled in the study. Basic features of all the patients were also compared. The rates of systolic blood pressure to workloads at the first stage, peak exercise, second, fourth and sixth minute of recovery were compared in normotensive men with both normal and abnormal coronary arteries. Statistical analysis: t test and stepwise regression was used. Results: The rates of systolic blood pressure to workloads were statistically importantly higher in men with normal blood pressure which had coronary artery disease compared to those with normal coronary arteries and normal blood pressure. Conclusions: In men with normal blood pressure high levels of systolic blood pressure to workload rates at the first stage to the end of exercise test can independently predict the presence of coronary artery disease, even in non-conclusive stress tests or when ECG doesn’t show any change during exercise.

Evaluating the Usability of a Next-Generation Heads-Up Display for Firefighters in a Virtual Environment

Virtual environments provide a rich and immersive platform to investigate how interfaces should be designed to support public safety operations. Virtual environments can be used to simulate the tasks, demands, and conditions of emergency response events while providing a controlled and safe environment for testing and developing new user interface capabilities. This paper presents an evaluation of a prototype AR-based heads-up display (HUD) that was integrated in a desktop-based virtual environment that simulated an emergency response scenario. Members of the first responder community (N = 90) completed a series of emergency response tasks and responded to a series of usability and user experience questions and workload ratings. The study used a 2 (Condition: HUD vs. No HUD) x 2 (Task Load: Radio monitoring task vs. No radio monitoring task) mixed experimental design. Participants provided very positive feedback on the utility of the prototype HUD for supporting task performance. Results and future research plans are discussed.

The Impact of False Alarms on Mental Workload, Stress and Performance: Implications for Medical Settings

The excessive number of auditory and false alarms (FAs) in medical settings (e.g. ICUs) negatively impact alarm response and performance on ongoing tasks. We examined the impact of two FA rates (low-40% and high-80% in a counterbalanced order repeated measures design) on 36 participants’ alarm responses with a concurrent working-memory (N-back) task. Participants made significantly more responses to FAs in the high FA condition relative to the low FA condition. An FA rate and order interaction revealed that participants who started in the low FA condition responded to fewer FAs in both the high and low FA conditions. Participants who started in the high FA condition responded to more than twice the number of FAs in the high FA condition compared to the low FA condition. Similarly, response time to correct detections (Hits) in the alarm and N-back tasks also revealed interaction effects between order and FA conditions. Participants who received the low FA condition first responded faster to true alarms in the high FA condition compared to those who received the high FA condition first. No significant main effects or interactions were observed for the number of Hits on the alarm task, response times to FAs in either task, nor for subjective ratings of mental workload or stress. Significant main and interaction effects observed on the N-back task were likely attributable to practice effects. These results underscore the need to reduce the number of FAs in medical settings and have implications for designing training paradigms to improve provider performance.

Cardiopulmonary exercise testing – methodological aspects

Cardiopulmonary exercise testing (CPET) allows for a non-invasive assessment of the integrative response of the pulmonary, cardiovascular, and skeletal muscle system during exercise. Therefore CPET in sports medicine covers a wide spectrum, ranging from diagnosis of disease, preoperative assessment, to athlete monitoring. High standards of reliability and validity are needed to ensure high-quality and diagnostically conclusive CPET data, necessitating a systematic process of quality assurance and control in the daily application of CPET. Therefore, methodological aspects such as CPET equipment principles, calibration, verification, maintenance, preparation, and plausibility checks need to be considered. As inter-technology, inter-device, and inter-unit differences in reliability and validity are reported for automated metabolic analyzers, the choice of the appropriate device should follow the purpose of use and comprehensible data on reliability and validity. To ensure high-quality measurements, careful calibration, and verification of all sensors, the integrated overall measurement performance, and maintenance of all equipment need to be performed and monitored longitudinally. Further, standardized ambient conditions, with adequate circulation and exchange of room air are essential. As the choice of the ergometer and protocol influences various target values in CPET, appropriateness for the selected diagnostic objective as well as a corresponding standardization is needed. While patients should receive pretest information that clearly outlines the test procedure, the correct attachment of the CPET equipment is of utmost importance. To detect and correct malfunctions of the metabolic analyzer and equipment, plausibility checks of the outcome measures validity should be performed during the resting, unloaded, loaded, and recovery test phase. A basic plausibility check should include adequate rest values and increases for a given workload rate of minute ventilation ( ˙VE), oxygen consumption ( ˙VO2) and respiratory exchange ratio (RER), using rules of thumb by Rühle. Before the final data interpretation is performed, e.g. ventilatory threshold or maximum oxygen consumption (˙VO2max) or ˙VO2peak determination, again a plausibility check should be performed and the patient‘s effort whether or not maximal should be determined. Consequently, a standard operating procedure for quality assurance and control, including an intuitive data visualization with thresholds for “pass”, “fail” or outliers and trends of concerns should be specifically defined, taught, and implemented in each facility. Key Words: CPET, Exercise Testing, Physical Fitness

Flight Technical Error and Workload During Head-Up Display Localizer Guided Takeoff

This was exploratory-in-nature follow-on research. The previous efforts focused on the operational impact of using a head-up display with localizer guidance in lieu of centerline lights for takeoff in low-visibility conditions. Herein, the goal was to examine the relationship between the subjective NASA task load index (TLX) workload ratings and flight technical error as the objective measure of performance. Instead of the total weighted scores, we analyzed the raw NASA TLX subscale ratings. Based on the analyses conducted, we proposed methods to use flight technical error data for predicting individual pilot workload ratings, and vice versa. The results indicated that the single best subjective predictor of flight technical error was the NASA TLX Performance subscale in both normal and abnormal operations. The most noteworthy finding was that when the abnormal condition included a trained failure, the ratings on the NASA TLX Temporal demand subscale had an inverse relationship with flight technical error. The pilots’ automatic response was to prioritize maintaining aircraft directional control and to compartmentalize tasks by priority. In contrast, when the pilots were presented with a failure that they had not been trained on, this automatic response was absent. The discussion also includes some notable limitations of this research and suggested mitigation methods.

O-004 The bias is out of the bag: IVF culture dish well number influences embryo selection decision-making and implantation outcome

Abstract Study question Is there a selection bias against embryos placed in higher-numbered wells inside a multi-well IVF culture dish. Does this selection bias alone impact implantation outcomes? Summary answer Top-quality embryos present in higher-numbered wells are statistically less likely to be selected for transfer, independent of any differences in quality or development between wells. What is known already Substantial intra-and inter-observer variability in embryo selection, as well as differences in quality assessment and laboratory environment, have been shown to affect IVF success. Currently many clinics have adopted stringent guidelines to control for human errors and workflow variation. Still, the impact of errors in laboratory and medical procedures was reported as high as 12%. This is particularly relevant for the IVF lab, where high workload and stress influence rate of errors and patient outcome. This groundbreaking study emphasizes how cognitive tendencies are inherent to the embryo selection process. Study design, size, duration This study used a retrospective dataset from three highly experienced fertility clinics (1 US and 2 European clinics). A total of 4,275 Fresh IVF cycles were analyzed. For each treatment cycle, embryo quality grades, corresponding embryo well numbers, day 5 selection and implantation outcomes were documented. All cycles were performed using the EmbryoSlide 12-well culture dish and a time-lapse system. All three datasets were analyzed separately and also combined. Participants/materials, setting, methods For each dataset, three analyses were conducted: (1) total number of selected embryos were calculated for each corresponding well number; (II) the proportion of implanted embryos, relative to the total number of selected embryos, were quantified to calculate the “success rate” for each well number; (II) the distribution of top-quality embryos between wells were quantified and compared. Results were normalized by total number of transferred embryos and IVF implantation success rates reported for each clinic. Main results and the role of chance A negative trend was found between well number, ranging from 1-12, and number of embryos selected for transfer. This trend was significant (p < 0.05) and occurred independently in each dataset. Odds ratios (OR) for the relation between selecting embryos for transfer from wells 1-5, and from 8-12 = Clinic A: 2.16, Clinic B: 1.78, Clinic C: 2.45. Alternative hypotheses were tested: (1) top-quality embryos are clustered in lower-numbered wells during culture; (2) enhanced embryo quality and conditions are found in lower-numbered wells, which should manifest in higher rates of implantation. Results for each clinic showed a statistically even distribution of top-quality embryos between wells (within 2 standard deviations from the mean; not significant), yet ‘success rate’ for transferred embryos increased by well number (by 12-30% between wells 1-5 and wells 8-12; OR = 1.19, 1.06, 1.08 for Clinic A, B, and C, respectively). An inverse trend existed between an embryo’s likelihood of being selected for transfer, and its likelihood of implanting. We conclude that embryologists may tend to select the first acceptable embryo for transfer. Embryos from higher-numbered wells were significantly more likely to implant, since they overcame this bias when equitably evaluated and selected for transfer. Limitations, reasons for caution Though our findings were significant, they need to be repeated on larger datasets with more inter-centre variation, and key embryo culture and outcome variables recorded. Wider implications of the findings This study emphasizes the inherent human error that exists inside IVF clinics. Machine learning systems that reduce human bias and increase objective standardization, even if they are not inherently better than embryologists, would improve implantation rates. Future studies should be directed toward AI based technologies that can accomplish this. Trial registration number Not Applicable

Ergonomics Evaluation of Manual Lifting Task on Biomechanical Stress in Symmetric Posture

Introduction: Manual lifting operations continue to play a key role in the industrial and service sectors, inflicting physical strain on the musculoskeletal system, despite advances in automation. As a result, an experiment is carried out to assess the impact of two lifting task parameters; weight and height, based on the estimation of subjective responses and biomechanical loading, while lifting the weight symmetrically in the sagittal plane. Also to recommend the safe limit for manual lifting tasks. Methods: Twelve volunteer male students in the age group of 21 to 26 years performed lifting tasks from floor to 5 different heights (below the knee to ear level), with 5 different weights (10 to 20 kg) using free-style lifting techniques. The load pan with no handle was used for lifting weight, which is typically adopted in the Indian building construction field. The subjective estimate was obtained using workload assessment by body discomfort chart. The biomechanical loading (loading rate) for each lifted weight and height was collected using a force platform. Results: The results showed that heavier weights produced higher stresses than lower weights. The loading rate was found to be almost similar at waist or knee level. The loading rate was observed to be linearly increasing after waist level. The overall workload rating seems to be a good correlate with the mean loading rate to some extent. Conclusion: It is proposed to keep the maximum acceptable lifting weight from floor to knee, up to the ear level is 15 kg, to prevent any musculoskeletal or chronic injury.

The Cycling Brain in the Workplace: Does Workload Modulate the Menstrual Cycle Effect on Cognition?

Recent decades have witnessed increased research efforts to clarify how the menstrual cycle influence females’ cognitive and emotional functions. Despite noticeable progress, the research field faces the challenges of inconsistency and low generalizability of research findings. Females of reproductive ages are a heterogeneous population. Generalizing the results of female undergraduates to women in the workplace might be problematic. Furthermore, the critical cognitive processes for daily life and work deserve additional research efforts for improved ecological validity. Thus, this study investigates cognitive performance across the menstrual cycle using a sample of young nurses with similar duties. We developed a mini-computerized cognitive battery to assess four mental skills critical for nursing work: cognitive flexibility, divided attention, response inhibition, and working memory. Participants completed the cognitive battery at menses, late-follicular, and mid-luteal phases. In addition, they were classified into low- and high workload groups according to their subjective workload ratings. Our results demonstrate a general mid-luteal cognitive advantage. Besides, this study reveals preliminary evidence that workload modulates the menstrual cycle effect on cognition. Only females of low workload manifest the mid-luteal cognitive advantage on divided attention and response inhibition, implying that a suitable workload threshold might be necessary for regular neuro-steroid interactions. Thus, this study advocates the significance of research focusing on the cycling brain under workloads.

Driver Vigilance Decrement is More Severe During Automated Driving than Manual Driving.

The present study compared the performance, workload, and stress associated with driver vigilance in two types of vehicle: a traditional, manually operated vehicle, and a partially automated vehicle. Drivers of partially automated vehicles must monitor for hazards that constitute automation failures and the need for human intervention, but recent research indicates that a driver's ability to do so declines as a function of time. That research lacked a comparison measure of driving without vehicle automation, so it is unknown to what degree these effects are specific symptoms of monitoring the roadway during an automated drive. Drivers in manual control of their vehicle must similarly monitor for hazards and may suffer similar vigilance decrements. Participants completed a simulated 40-minute drive while monitoring for hazards. Half of participants completed the drive with an automated driving system that maintained speed and lane position; the remaining half manually controlled the vehicle's speed and lane position. Driver sensitivity to hazards decreased and tendency to make false alarms increased over time in the automated control condition, but not in the manual control condition. Drivers in both conditions detected fewer hazards as the drive progressed. Ratings of workload and task-induced stress were elevated similarly in both conditions. Partially automated driving appears to uniquely impair driver vigilance by reducing the ability to discriminate between benign and dangerous events in the driving environment as the drive progresses. Applied interventions should target improvements in driver sensitivity to hazardous situations that signal potential automation failures.

Constructing Neural Network Model to Evaluate and Predict Human Error Probability in Nuclear Power Plants Based on Eye Response, Workload Rating, and Situation Awareness

The accurate assessment of human error probability (HEP) has an important impact on the safety of nuclear power plants. Therefore, it is necessary to develop a HEP model. This study analyzes the validity, sensitivity, and relationship between HEP and the indices of eye response and the subjective rating method. The analysis result showed that there is a correlation between HEP and the indices of eye response, subjective workload, and situation awareness level. Therefore, a back propagation neural network model was developed based on these indices. The correlation coefficient is more than 0.95 between the predicted data of the developed model and the target data. Also, the root mean square error was 0.0073, 0.0083, and 0.0077, and the determination coefficient was 0.965, 0.933, and 0.931 for the training, validation, and testing data sets, respectively. Therefore, the developed back propagation neural network model has reliable prediction accuracy for HEP.

Subjective and objective assessments of mental workload for UAV operations.

Unmanned Aerial Vehicles (UAVs) have created safety problems for the publics. Assessments of the mental workload for UAV operations are essential to realize the causes of UAV accidents. To test the following hypotheses: i. mission difficulty in UAV operation affects both subjective and objective measures of mental workload; ii. mission difficulty affects number of failures in UAV operation. Fourteen male adults participated as UAV operators after attending a UAV training course. They performed four flight missions of different difficulty levels. During their flight missions, their heart rate and inter-beat interval (IBI) were collected. Upon completing each flight mission, the participants gave subjective ratings of mental workload using three commonly adopted assessment tools. The time of flight and number of failures in flight operations were also recorded. The results showed that mission difficulty affected the scores of all three assessment tools significantly. Mission difficulty also affected number of failures and IBI significantly. The scores of the three assessment tools were highly correlated (ρ= 0.7 to 0.83, p < 0.001) with one another. The results of the three subjective ratings were also consistent with that of the IBI data. High mental workload in UAV operation could lead to poor flight performance.

Mental Workload in Neuropsychology: An Example With the NASA-TLX in Adults With HIV.

A preliminary set of analyses are presented, where workload was examined in 32 adults infected with the human immunodeficiency virus (HIV). Like the current COVID-19 pandemic (caused by the SARS-CoV-2 virus), HIV can produce a wide variety of symptoms, including various levels of cognitive dysfunction. In fact, a recent meta-analysis estimates that of the 39 million adults infected globally with HIV, 42.6% exhibit some form of HIV-associated neurocognitive disorder. A common cognitive symptom in HIV is decline in attention and executive functioning. Though typically examined by clinicians with less precise traditional paper-and-pencil neuropsychological tests, we examined this aspect of cognitive functioning using a more psychometrically sophisticated task as we had HIV-positive adults perform a computerized tracking task in single, dual, and tri-task conditions via the Multi-Attribute Task (MAT) Battery. Also assessed was mental workload, with the NASA-Task Load Index (NASA-TLX), rarely used in neuropsychology but a standard tool in human factors and neuroergonomics research. As expected, tracking performance declined with task condition difficulty (p < 0.001). Although no direct statistical comparisons were made, MAT performance here appeared worse than the MAT performance of various other groups reported in the research literature and in our laboratory. Ratings of workload also tended to increase as a function of task condition difficulty (p < 0.001). Plotting MAT tracking performance against the Mental Demand subscale scores, large individual differences in this aspect of workload were evident in both optimal and sub-optimal tracking performance. To examine likely variables with a potential impact on Mental Demand, a variety of variables (nadir CD4 count, viral load, depression symptoms, diagnosis of AIDS, presence of opportunistic infection, general cognitive status, etc.) were examined in relation to the Mental Demand scale, with age showing a significant association (r = 0.41, p = 0.022) and a diagnosis of AIDS showing trend associations (ps ≥ 0.066). Findings suggesting a deficit in metacognition or insight are also discussed. It is argued that assessment of workload (and its various aspects or components) can provide valuable additional information in neuropsychology.

Human factors engineering of BCI: an evaluation for satisfaction of BCI based on motor imagery.

Existing brain-computer interface (BCI) research has made great progress in improving the accuracy and information transfer rate (ITR) of BCI systems. However, the practicability of BCI is still difficult to achieve. One of the important reasons for this difficulty is that human factors are not fully considered in the research and development of BCI. As a result, BCI systems have not yet reached users' expectations. In this study, we investigate a BCI system of motor imagery for lower limb synchronous rehabilitation as an example. From the perspective of human factors engineering of BCI, a comprehensive evaluation method of BCI system development is proposed based on the concept of human-centered design and evaluation. Subjects' satisfaction ratings for BCI sensors, visual analog scale (VAS), subjects' satisfaction rating of the BCI system, and the mental workload rating for subjects manipulating the BCI system, as well as interview/follow-up comprehensive evaluation of motor imagery of BCI (MI-BCI) system satisfaction were used. The methods and concepts proposed in this study provide useful insights for the design of personalized MI-BCI. We expect that the human factors engineering of BCI could be applied to the design and satisfaction evaluation of MI-BCI, so as to promote the practical application of this kind of BCI.