NASA-TLX Questionnaire Research Articles

Cognitive Analyses for Interface Design Using Dual N-Back Tasks for Mental Workload (MWL) Evaluation.

In the manufacturing environments of today, human-machine systems are constituted with complex and advanced technology, which demands workers' considerable mental workload. This work aims to design and evaluate a Graphical User Interface developed to induce mental workload based on Dual N-Back tasks for further analysis of human performance. This study's contribution lies in developing proper cognitive analyses of the graphical user interface, identifying human error when the Dual N-Back tasks are presented in an interface, and seeking better user-system interaction. Hierarchical task analysis and the Task Analysis Method for Error Identification were used for the cognitive analysis. Ten subjects participated voluntarily in the study, answering the NASA-TLX questionnaire at the end of the task. The NASA-TLX results determined the subjective participants' mental workload proving that the subjects were induced to different levels of mental workload (Low, Medium, and High) based on the ANOVA statistical results using the mean scores obtained and cognitive analysis identified redesign opportunities for graphical user interface improvement.

UAV Operators’ Gaze Behavior and Workload in Simulation Flights – a preliminary study

Effective processing of information from the sense of sight affects the efficiency and safety of flight operations. Differences in visual behavior and workload between UAV operators with various flight experience during basic flight maneuvers were identified as the research problem. The participants' visual behavior was record using an eye tracker and their workload was measured using NASA TLX questionnaire. The research subjects' task was to perform a simulation UAV flights with different difficulty levels. The aim of article are preliminary research to make conclusions about differences in gaze and workload level according to operators experience and due to two simulation scenarios. Eye tracking and NASA TLX variables differentiate the difficulty levels of the simulations performed. For experts group values of eye tracking variables was similar during each level of task. However, NASA TLX results in experts group shows the difference between each task. Based on the result can be seen, that experience differentiate the level of subjects' workload during the operations performed. The results of the eye tracking study suggest that performing basic maneuvers develops strategies for scanning the space. It is advisable to conduct further research with larger groups of operators taking into account the division into groups with varying different licenses.

Enhanced Human–Robot Interface With Operator Physiological Parameters Monitoring and 3D Mixed Reality

Remote robotic interventions and maintenance tasks are frequently required in hazardous environments. Particularly, missions with a redundant mobile manipulator in the world’s most complex machine, the CERN Large Hadron Collider, are performed in a sensitive underground environment with radioactive or electromagnetic hazards, bringing further challenges in safety and reliability. The mission’s success depends on the robot’s hardware and software, and when the tasks become too unpredictable to execute autonomously, the operators need to make critical decisions. However, in most current human-machine systems, the state of the human is neglected. In this context, a novel 3D Mixed Reality (MR) human-robot interface with the Operator Monitoring System (OMS) was developed to advance safety and task efficiency with improved spatial awareness, advanced manipulator control, and collision avoidance. However, new techniques could increase the system’s sophistication and add to the operator’s workload and stress. Therefore, for operational validation, the 3D MR interface had to be compared with an operational 2D interface, which has been used in hundreds of interventions. With the 3D MR interface, the execution of precise approach tasks was faster, with no increased workload or physiological response. The new 3D MR techniques improved the teleoperation quality and safety while maintaining similar effects on the operator. The OMS worked jointly with the interface and performed well with operators with varied teleoperation backgrounds facing a stressful real telerobotic scenario in the LHC. The paper contributes to the methodology for human-centred interface evaluation incorporating the user’s physiological state: heart rate, respiration rate and skin electrodermal activity, and combines it with the NASA TLX assessment method, questionnaires, and task execution time. It provides novel approaches to operator state identification, the GUI-OMS software architecture, and the evaluation of the 3D MR techniques. The solutions can be practically applied in mission-critical applications, such as telesurgery, space robotics, uncrewed transport vehicles and semi-autonomous machinery.

Optimal Signal Processing for Steady Control of a Robotic Arm Suppressing Hand Tremors for EOD Applications

Teleoperated robotics in recent years has proven to be valuable support in EOD tasks; a remarkable improvement in the systems that control these robots has been the Natural User Interfaces (NUI); however, the research that implements this type of system does not focus on the stability of the robotic arm movements, necessary for this type of applications due to the danger of working with explosives. In this paper, we propose the implementation of an Optimal Signal Processing for a NUI interface based on the Leap Motion (LM) controller. The main objective of this research is to correctly identify the intentional movements of the operator, achieve high stability of the robotic gripper and suppress the physiological tremors from the hand of the operator, considering not to increase the mental workload and not decrease the usability of the system. The signal processing proposed in this paper is composed of three filtering algorithms: Kalman, FIR, and moving average with a threshold. In addition, the obtained results are compared with the most representative processing of recent research using LM for robotic arm control. To evaluate and validate the proposed signal processing, a target path tracking test, a stability analysis of the robotic gripper, and a performance analysis in the execution of Pick and Place tasks, NASA-TLX and SUS questionnaires are developed. Finally, the proposed Optimal Signal processing is implemented in the DOBOT-MAGICIAN and tested by police officers of the EOD Unit-Arequipa (UDEX-AQP); the results indicate a reduction of the average Vibration of 31.61% and the Target Path Tracking error of 67.57%.

ANALYSIS OF MENTAL WORKLOAD USING THE NASA-TLX METHOD FOR PRODUCTION WORKERS AT PT. DOLOMITES PUTERA TAMIANG

The workload is the difference between the ability of workers with job demands. If the ability of workers is higher than the demands of the job, then boredom will appear, and vice versa. The method used is the NASA TLX method, and the instrument used is the NASA-TLX questionnaire given to 16 respondents. Results and Discussion The average of the six indicators of shift 1 is an indicator of mental needs with an average value of 146.88, an indicator of physical needs with an average value of 237.5, an indicator of time needs with an average value of 140, a performance indicator with a value of an average of 119.38, an indicator of the level of effort with an average value of 247.88, an indicator of the level of frustration with an average value of 82.5. In conclusion, the mental workload level of the production workers for both shifts is included in the high workload category. The dominant indicators for the activities of the first shift workers in the production section are the level of effort indicators, indicators of physical needs, indicators of mental needs, indicators of time requirements, and performance indicators. . The dominant indicators in worker activity in Shift II in the production section are indicators of physical needs, levels of effort, indicators of time requirements, indicators of mental needs, performance indicators, and the last indicator is frustration.

Hey Max, Can You Help Me? An Intuitive Virtual Assistant for Industrial Robots

Assisting employees in acquiring the knowledge and skills necessary to use new services and technologies on the shop floor is critical for manufacturers to adapt to Industry 4.0 successfully. In this paper, we employ a learning, training, assistance-formats, issues, tools (LTA-FIT) approach and propose a framework for a language-enabled virtual assistant (VA) to facilitate this adaptation. In our system, the human–robot interaction is achieved through spoken natural language and a dashboard implemented as a web-based application. This type of interaction enables operators of all levels to control a collaborative robot intuitively in several industrial scenarios and use it as a complementary tool for developing their competencies. Our proposed framework has been tested with 29 users who completed various tasks while interacting with the proposed VA and industrial robots. Through three different scenarios, we evaluated the usability of the system for LTA-FIT based on an established system usability scale (SUS) and the cognitive effort required by the users based on the standardised NASA-TLX questionnaire. The qualitative and quantitative results of the study show that users of all levels found the VA user friendly with low requirements for physical and mental effort during the interaction.

Beban Kerja Psikologis Perawat Pasien Covid-19: Metode NASA-TLX

Covid-19 with a very fast transmission rate and requires serious treatment from medical personnel, especially nurses in hospitals, which results in long-term psychological disorders. This research analyzes the psychological workload of nurses for Covid-19 patients at Polewali Mandar District Hospital. This research is qualitative research with a case study approach in which data is collected using the NASA-TLX questionnaire through interviews. The sample in this study was nurses for Covid-19 patients at the Polewali Mandar District Hospital by purposive sampling, totaling 45 people. The data were analyzed using descriptive analysis to analyze the psychological workload of nurses for Covid-19 patients through WWL calculations. The calculation of the NASA-TLX score, overall the nurses of Covid-19 patients at Polewali Mandar Hospital was in the category with a moderate level of psychological workload with an average WWL (weighted workload) of 63.32. Based on the graph, the six elements in the final score that affect the NASA-TLX calculation are Mental Demand (MD) with an average score of 239, and Temporal Demand (TD) with an average score of 164. It is concluded that psychological workload plays an important role in a very large role in carrying out work, especially for Covid-19 nurses at Polewali Hospital.

Adaptative damping assistance in bimanual laparoscopic surgery.

Laparoscopic surgery has demonstrated various advantages for the patients' care, but also presents some difficulties for the surgeons, such as kinematic restrictions. Robotic comanipulation, in which control of instruments is shared between the robot and the surgeon, can provide adaptative damping assistance which allows stabilisation of movements. The objective of the present study was to determine the contribution of this assistance on a bimanual laparoscopic task. Adaptative damping was studied on Peg Transfer task, performed by eighteen surgery-naive subjects. This exercise was repeated seven times without (Classic repetitions) and seven times with comanipulated robots (Robot repetitions), in a randomised order. We measured task performance, using Peg Transfer score; gesture performance, using hand oscillations and travelled distance; eye-tracking movements as an indicator of emergence of expertise. Participants' perceived workload was assessed by NASA TLX questionnaire, and difference in impression between the two conditions by UEQ questionnaire. Adaptative damping improved gesture performance (oscillations F(1,17) = 23.473, p < 0.001, η2 = 0.580), with a statistically significant simple effect on the tool oscillation for both non-dominant (p < 0.001) and dominant hands (p = 0.005), without influencing task performance (mean Peg Transfer score t(17) = 0.920, p = 0.382, d = 0.29), but deteriorating eye-tracking movements associated with emergence of expertise (mean fixation rate per second F(1,17) = 6.318, p = 0.022, η2 = 0.271), at the cost of a high perceived workload (NASA TLX score 59.78/100). Assistance by adaptative damping applied by comanipulated robots improved gesture performance during a laparoscopic bimanual task, without impacting task's performance without allowing the emergence of comportments associated with an expertise, and at the cost of a high perceived workload. Further research should investigate this assistance on more precise and clinical tasks performed by professionals.

Applying Sonification to Sketching in the Air With Mobile AR Devices

With more and more mobile devices (such as smart phones and tablets) supporting augmented reality (AR), using these devices to sketch in mid-air has become a popular application direction. However, due to the small display size of these devices, the user's field of view is limited and cannot see the context of graphics, which leads to the drawn graphics deviating from their expectations. In this article, we applied sonification technology to mid-air sketching with mobile AR device, and proposed a new method to address this problem. In our first experiment, we verified the feasibility of our method. Our experimental results showed that sonification can effectively reduce the deviation caused by a narrow field of view. In our second experiment, we further explored the application ability of this method in a wider range of sketching. Our experimental results showed that sonification can improve the aspect ratio of the drawn graphics. In addition, the results of the NASA-TLX questionnaire showed that the participants' mental demand and effort decreased significantly, and their subjective performance increased significantly. We proposed a new method, which can effectively improve the accuracy of mid-air sketching with a mobile AR device.

Reperfused human cadaver as a new simulation model for colonoscopy: a pilot study.

The reperfused human cadaver is a validated simulator for surgery. We aimed to use it as a colonoscopy simulator. Novices, intermediates and skilled participants in gastrointestinal endoscopy were included. They performed one colonoscopy on a reperfused human cadaver and reaching rates, time, and length needed to reach anatomical landmarks were reported for construct validity analysis. We also assessed our model realism (SRS survey), educational content (CVS survey) and task load (NASA-TLX index). Score items were collected and defined as "favorable" when items were rated ≥ 5/7 with an inter-quartile range (IQR) overlapping four, and "very favorable" when rated ≥ 5/7 with an IQR excluding four (neutral). Primary endpoints were the rectosigmoid junction (RSJ) reaching rate and the descending colon (DC) reaching time. Secondary objectives were SRS, CVS and NASA-TLX questionnaire results. A total of 11 skilled participants, 5 intermediates and 8 novices were included. Skilled participants reached RSJ more often than novice and intermediary groups, respectively, 100%, 80% and 75% without differing significantly. They reached DC more frequently (100% for skilled, 80% for intermediates and 50% for novices, p = 0.018). The median time to reach RSJ (59, 272 and 686s for skilled, intermediates and novices group, respectively) and DC (90, 534 and 1360s for skilled, intermediates and novices) was significantly shorter for skilled participants (both p < .01). Nineteen out of the 22 items composing the realism survey obtained "very favorable" and "favorable" scores. Educational content was designated as "very favorable". Mental, physical, and technical demands were gradually higher the lower the initial level of experience. Reperfused human cadaver model has the potential to be valid simulation tool for diagnostic colonoscopy training.

Save our surgeons (SOS) – an explorative comparison of surgeons’ muscular and cardiovascular demands, posture, perceived workload and discomfort during robotic vs. laparoscopic surgery

PurposeConventional laparoscopic surgery (CLS) imposes an increased risk of work-related musculoskeletal disorders. Technical innovations, such as robotic-assisted laparoscopic surgery (RALS), may provide ergonomic benefits. We compare the surgeon`s work-related demands of CLS vs RALS for benign hysterectomies.MethodsFive specialists (3 females, 2 males) each performed four RALS and four CLS as part of their daily clinical routine. During the surgical procedures, muscular demands were assessed by bipolar surface electromyograms of the descendent trapezius, extensor digitorum and flexor carpi radialis muscles as well as cardio-vascular demands by electrocardiography, and neck, arm and torso posture by gravimetrical position sensors. Additionally, the subjects rated their level of perceived workload (NASA TLX questionnaire with 6 dimension) and musculoskeletal discomfort (11-point Likert-scale, 0–10).ResultsMuscular demands of the trapezius and flexor carpi radialis muscles were lower with RALS but extensor digitorum demands increased. Cardiovascular demands were about 9 heart beats per minute (bpm) lower for RALS compared to CLS with a rather low median level for both surgical techniques (RALS = 84 bpm; CLS 90 bpm). The posture changed in RALS with an increase in neck and torso flexion, and a reduction in abduction and anteversion position of the right arm. The perceived workload was lower in the physical demands dimension but higher in the mental demands dimension during RALS. Subjective musculoskeletal discomfort was rare during both surgical techniques.ConclusionsThis explorative study identified several potential ergonomic benefits related to RALS which now can be verified by studies using hypothesis testing designs. However, potential effects on muscular demands in the lower arm extensor muscles also have to be addressed in such studies.

AppYourself Instant Store (Case Study: SMEs Industry in Aceh Province)

The purpose of this study is to implement the use of AppYourself to create an Instant Store that can be used in Small and Medium Enterprises (SMEs) Industry in Aceh Province. The Software Development Life Cycle method used is IDI. IDI is a combination of iterative design / iterative method and incremental build model that is used for software development. Testing and measurement based on usability level using the People at the Center of Mobile Application Development (PACMAD) model based on its seven aspects. This research uses Performance Measurement, SUS Questionnaire, NASA-TLX Questionnaire, and RTA Questionnaire in data collection. The data was measured using usability metrics, statistical tests, and calculation formulas from the questionnaire. The results of this study have succeeded in making an application called InstantStore by involving several stages from data collection to testing. The results of the initial test or pre-evaluation and final testing or post-evaluation, it can be concluded that after an evaluation by designing a prototype of improvement recommendations using the rules of The 4 Golden Rules Of User Interface Design, there is a significant increase, based on the results of statistical tests on testing Pre-evaluation shows that there are significant differences between respondents in South Aceh Regency and Banda Aceh City on aspects of efficiency, memorability, satisfaction, and cognitive load. In addition to the aspects of effectiveness, learnability, and errors there is no significant difference between respondents. While the results obtained from statistical tests in the final test (post-evaluation) there are no differences between respondents to the seven aspects of the usability of the PACMAD model.

Multisensory Fusion, Haptic, and Visual Feedback Teleoperation System Under IoT Framework

The combination of teleoperating robots and the Internet of Things (IoT) could be employed in many areas, including remote nursing and semi-mechanical control. However, it is known that subjects can quickly encounter physical and mental fatigue, which can potentially lower accuracy in teleoperation. To address this issue, this article presents a closed-loop teleoperation system based on multisensory fusion, visual, and haptic feedback within the IoT framework. Various sensors for electromyography, inertial measurement unit, and mechanical hand control system are deployed to obtain body signals from participants, subsequently processed by artificial intelligence methods. Resistive sensors are installed at the robotic hand side to learn the contact force between the robot hand and the grasped object. To allow the user to understand the contact force levels, a haptic interface is equipped to provide three-level mechanical vibrations. To help users identify and trace different objects, a region convolution neural network for detecting 100 different categories of things is constructed. In addition, the real-time control (delay <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mathbf {&lt; } 110$ </tex-math></inline-formula> ms) is offered by a tri-layered IoT architecture. The feasibility of the proposed technique is validated by a grasping task carried out by 20 volunteers. During experiments, it is observed that merely 10.8 s is averagely needed for participants in finishing the task, with a high average success rate of 97%. Besides, NASA-TLX questionnaire and maximum voluntary contraction test report that users suffer light mental and physical fatigue when the proposed technique is used.

The influence of physical and mental workload on the safe behavior of employees in the automobile industry

This study aimed to investigate the influence of physical and mental workload on safe behavior of employees in the automobile industry. The 150 workers of the two industries of machining and foundry of an automobile parts manufacturer participated in this correlational study. Safety behavior, NASA-TLX, and Borg scale questionnaires were used to collect data. Independent t-test, analysis of variance and Pearson correlation coefficient applied to the analysis of data. The NASA-TLX showed that the dimensions of physical and mental demand had the highest score and the performance had the lowest score. Excessive physical pressure was also reported among workers. The Score of safety observance, safety participation, and safety behavior were at a moderate level. There was a significant difference in the physical workload of employees who had an accident and did not have an accident (P = 0.001). The results showed that if the same mental workload had been imposed on workers and simultaneously more physical workload had been experienced, the probability of an accident increased. The overall mental workload and physical pressure among workers were reported at a high level. Safe behaviors were moderate among employees. Therefore, the implementation of effective intervention programs to adjust workload, participatory ergonomics, provide workload balance to improve job satisfaction, eliminate inappropriate working conditions and increase the number of operators, management programs such as job rotation between Machining and Foundry and other workshops, increase rest time and creation of a strong teamwork safety climate can reduce physical and mental workload and prevent accident among workers, improve their performance and wellbeing.

Quantification of Mental and Physiological Workload Associated with two Specialised Military Running Events on Different Terrains

Intense training regimes are practiced across military facilities to develop soldiers’ mental and physical abilities to meet the demands of modern-day warfare. Two short-duration military runs through the jungle and flat natural tracks were selected to quantify their mental and physiological workloads and explore track-specific differences. Two groups of healthy Indian soldiers (n=43 and 30; similar age, height, and weight) participated in time-bound 2.4 km runs on the jungle and flat natural tracks. Physiological variables, speed, and elevation with environmental parameters like temperature and humidity were recorded throughout the exercises. Subjective responses through NASA-TLX questionnaires were collected after the exercises. Mann-Whitney ‘U’ test was applied to find out the level of significance between groups.Physiological demands of runs on the jungle and flat natural track were similar (heart rate- 178.9 and 178.4 b/min; breathing rate- 42.0 and 46.6 breaths/min respectively; body temperature- 37.6℃ for both groups). The run on the jungle track needed a lower peak acceleration of 2.5 g (2.9 g on the flat track) and a higher variation in speed (4-16 knots). Participants expressed significantly high responses after the run on the jungle track. Run on the jungle track was physically intense, required adjustments in speed and acceleration to negotiate with the natural obstacles like uneven terrain and slippery surfaces. Besides this, environmental heat and higher humidity probably led to an increase in mental workload. The run on the flat natural track needed steady physical effort, fewer mechanical adjustments, and showed lower subjective responses.

Assessment of instantaneous cognitive load imposed by educational multimedia using electroencephalography signals.

The use of multimedia learning is increasing in modern education. On the other hand, it is crucial to design multimedia contents that impose an optimal amount of cognitive load, which leads to efficient learning. Objective assessment of instantaneous cognitive load plays a critical role in educational design quality evaluation. Electroencephalography (EEG) has been considered a potential candidate for cognitive load assessment among neurophysiological methods. In this study, we experiment to collect EEG signals during a multimedia learning task and then build a model for instantaneous cognitive load measurement. In the experiment, we designed four educational multimedia in two categories to impose different levels of cognitive load by intentionally applying/violating Mayer’s multimedia design principles. Thirty university students with homogenous English language proficiency participated in our experiment. We divided them randomly into two groups, and each watched a version of the multimedia followed by a recall test task and filling out a NASA-TLX questionnaire. EEG signals are collected during these tasks. To construct the load assessment model, at first, power spectral density (PSD) based features are extracted from EEG signals. Using the minimum redundancy - maximum relevance (MRMR) feature selection approach, the best features are selected. In this way, the selected features consist of only about 12% of the total number of features. In the next step, we propose a scoring model using a support vector machine (SVM) for instantaneous cognitive load assessment in 3s segments of multimedia. Our experiments indicate that the selected feature set can classify the instantaneous cognitive load with an accuracy of 84.5 ± 2.1%. The findings of this study indicate that EEG signals can be used as an appropriate tool for measuring the cognitive load introduced by educational videos. This can be help instructional designers to develop more effective content.

Assessing the Impact of Work Activities on the Physiological Load in a Sample of Loggers in Sicily (Italy).

Occupational logging activities expose workers to a wide range of risk factors, such as lifting heavy loads, prolonged, awkward positioning of the lower back, repetitive movements, and insufficient work pauses. Body posture has an important impact on the level of physiological load. The present study involved a group of 40 loggers in the province of Enna (Sicily, Italy) with the aim of defining the impact of logging activities on the workers’ physiological strain during the three primary work tasks of felling, delimbing, and bucking. The Zephyr Bioharness measurement system was used to record trunk posture and heart rate data during work tasks. The NASA TLX questionnaire was used to explore workers’ effort perception of the work tasks. Based on our results, the most demanding work task was tree felling, which requires a higher level of cardiac cost and longer periods spent in awkward trunk postures. The perceived physiological workload was consistently underestimated, especially by the more experienced loggers. Lastly, as the weight of the chainsaw increased, the cardiac load increased.

Improvements in musculoskeletal symptoms, mental workload and mental fatigue: Effects of a multicomponent ergonomic intervention among call center workers

Call center workers are highly susceptible to work-related musculoskeletal disorders (WRMSDs) as well as mental stress. Nonetheless, there has been a surprising paucity in the body of the research regarding interventions among call center workers. The purpose of this paper is to investigate the effectiveness of a multicomponent ergonomic intervention program on mental workload, mental fatigue and WRMSDs of call center employees. A non-randomized interventional study with a single group pretest-posttest design was conducted among 84 call center workers of a private telecommunication company in the city of Tehran, Iran. At the baseline, data regarding WRMSDs prevalence, mental workload and mental fatigue were collected by means of standard Nordic, NASA-TLX and SOFI questionnaires, respectively. Then, subjects participated in a multifaceted intervention program including comprehensive office ergonomic training, work layout improvement, supervised on-site face to face visits, and provision of quality break time encompassing regular exercise program. Follow-up assessment was carried out after 6 months. After the intervention, prevalence of WMSDs in the neck (10%, P = 0.022), lower back (8.4%, P = 0.04), and knees (9.5%, P = 0.02) decreased significantly, while improvements in other body areas remained insignificant. Results also showed a significant decrease in overall score of mental demand (P = 0.000) as well as three of its subscales including performance (P = 0.02), effort (P = 0.001), and frustration (P = 0.025). Additionally, positive effect of the intervention was also observable on overall mental fatigue of call center workers (P = 0.016). As for its subscales, Lack of energy was reported to decrease meaningfully (P = 0.007) while lack of motivation did not change significantly (P = 0.240). Although the primary focus of many ergonomic interventions has remained to measure physical outcomes of the work place, our findings show that multicomponent interventions are indeed capable of boosting cognitive aspects of the work as well. The future studies should consider investigating such outcomes.

Sensory substitution of elbow proprioception to improve myoelectric control of upper limb prosthesis: experiment on healthy subjects and amputees

BackgroundCurrent myoelectric prostheses lack proprioceptive information and rely on vision for their control. Sensory substitution is increasingly developed with non-invasive vibrotactile or electrotactile feedback, but most systems are designed for grasping or object discriminations, and few were tested for online control in amputees. The objective of this work was evaluate the effect of a novel vibrotactile feedback on the accuracy of myoelectric control of a virtual elbow by healthy subjects and participants with an upper-limb amputation at humeral level.MethodsSixteen, healthy participants and 7 transhumeral amputees performed myoelectric control of a virtual arm under different feedback conditions: vision alone (VIS), vibration alone (VIB), vision plus vibration (VIS + VIB), or no feedback at all (NO). Reach accuracy was evaluated by angular errors during discrete as well as back and forth movements. Healthy participants’ workloads were assessed with the NASA-TLX questionnaire, and feedback conditions were ranked according to preference at the end of the experiment.ResultsReach errors were higher in NO than in VIB, indicating that our vibrotactile feedback improved performance as compared to no feedback. Conditions VIS and VIS+VIB display similar levels of performance and produced lower errors than in VIB. Vision remains therefore critical to maintain good performance, which is not ameliorated nor deteriorated by the addition of vibrotactile feedback. The workload associated with VIB was higher than for VIS and VIS+VIB, which did not differ from each other. 62.5% of healthy subjects preferred the VIS+VIB condition, and ranked VIS and VIB second and third, respectively.ConclusionOur novel vibrotactile feedback improved myoelectric control of a virtual elbow as compared to no feedback. Although vision remained critical, the addition of vibrotactile feedback did not improve nor deteriorate the control and was preferred by participants. Longer training should improve performances with VIB alone and reduce the need of vision for close-loop prosthesis control.

Relationship of Age, Duration of Work and Environmental Temperature With Worker Mental Workload

‘Workload’ refers to the job demands faced by workers compared to individual capacities. A high workload may cause overstress and injury. This study aimed to determine the relationship of age, duration of work, and temperature with workload. Descriptive quantitative methods were used with a cross sectional design. The sample included 40 respondents. The NASA-TLX questionnaire and thermohydrometer were used to collect the data which were analyzed using the Chi-square test. The findings showed that 55% of the workers had a moderate mental workload, and there was a relationship between age and mental workload (p-value = 0.045), while the duration of work (p = 0.340) and temperature climate (p = 0.602) did not have a relationship with mental workload. The mental workload of workers increased with an increase in age, so the recommendation given is to provide a workload according to the capacity of the worker.&#x0D; Keywords: workload, temperature climate, age, duration of work, worker