Subjective Workload Assessment Research Articles

The Effect of Touchscreen Layout Division on the Usability and Driving Safety of In-Vehicle Information Systems

Compared to traditional physical controls, in-vehicle touchscreen interaction relies more on vision. Irrational In-Vehicle Information System (IVIS) interface layout design can lead to decreased driver performance and even serious traffic accidents. This study investigated the impact of IVIS layouts on usability and driving safety. We extracted and analyzed the current mainstream IVIS homepage layouts in the market and summarized four different layout structures. An experiment was conducted on a driving simulator to examine the usability of the IVIS layout design based on task reaction time, error rate, NASA-TLX (a subjective workload assessment scale developed by NASA), and subjective preference (PREF). The safety issues of IVIS layout design were also examined based on standard deviation lane position (SDLP), speed variation (SV), mean glance time, mean number of glances, and blink frequency. This study recorded and evaluated the driving performance of 40 participants during real driving tasks at four speeds (0, 60, 90, and 120 km/h). Results showed that there were significant differences in task reaction time, NASA-TLX, PREF, mean glance time, SDLP, and SV among the four layouts. Furthermore, we observed that these four layouts had varying effects on usability and driving safety at four speeds. In the stationary state, the three-partition layouts were more efficient, while the two-partition layouts had more advantages during driving. Meanwhile, the horizontal dock bar layout interfaces have more advantages compared to the vertical dock bar interface. The study provides empirical evidence for optimizing the IVIS interface layout design for enhanced usability and driving safety.

Machine learning-based multimodal fusion recognition of passenger ship seafarers’ workload: A case study of a real navigation experiment

Passenger ships have complex transportation systems and seafarers face high workloads, making them susceptible to serious injuries and fatalities in the event of accidents. Existing unimodal workload recognition for seafarers mainly focuses on fixed load induction in bridge simulators, whereas a multimodal approach using multi-sensor data fusion can overcome the reliability and sensitivity limitations of a single sensor. To accurately identify the workload of seafarers, we propose a machine learning-based multimodal fusion method at the feature layer and utilise the Gini index to determine the feature weight of the multimodal data. Through a real ship navigation experiment, the subjective workload assessment technique (SWAT) was employed to collect the continuous workload scores of 24 seafarers in daily tasks. Further, the Dempster–Shafer evidence theory was used to integrate these scores with the unsafe behavior probability of seafarers to obtain a calibrated workload. Electroencephalogram (EEG), electrocardiogram (ECG), and electrodermal activity (EDA) signals were collected in real time, and a high-dimensional feature matrix was extracted to construct the workload recognition model. Random forest, XGBoost, and back-propagation neural networks were used to establish multimodal fusion workload recognition models at the feature-fusion stage, and the model performances were compared. The results showed that the multimodal fusion based on EEG, ECG, and EDA had an excellent recognition accuracy. The XGBoost algorithm has better performance with an accuracy of 85.72%, which is an increment of 9.49% compared to that of the unimodal algorithm, and this improvement passed the statistical significance test. Important features suitable for multimodal fusion recognition were also analysed. The findings of this study have profound significance for enhancing risk control measures pertaining to human factors and ensuring navigation safety.

Common Subjective Mental Workload Assessment Measures: Advantages and Disadvantages

Background: The amount of mental resources required to perform simultaneously a series tasks is considered as mental workload (MWL). High and Low mental workload in the workplace is usually associated with mental fatigue, decreased performance, human error, and even harmful long-term health effects. Among the various MWL assessment techniques, the outcome measures such as questionnaires are easier and more practical in workplace settings. We aimed to compare the three current commonly advocated and used questionnaires. Material and Methods: Three common different outcome measures for evaluation of the MWL are NASA Task Load Index (NASA-TLX), Subjective Workload Assessment Technique (SWAT), and the CarMen-Q workload questionnaire. Among them the NASA-TLX is well known and more popular with six subscales that are used extensively in industrial and official workplaces. SWAT is the simplest one with three dimensions. The NASA-TLX is preferable method because of its higher sensitivity, especially in low MWL conditions. The CarMen-Q questionnaire is a new questionnaire with 29 items and 4 subscales that focuses on cognitive workload and mental fatigue. Conclusion: SWAT is the simplest and less sensitive measure than the NASA-TLX and CarMen-Q questionnaires. In contrast, the NASA-TLX is widely used and more known instrument for MWL evaluation.

Development of a Subjective Workload Assessment Technique Model as an Effort to Improve Performance Nurse in Home Inpatient Room Royal Prima Hospital

It is hoped that the performance of all medical and non-medical personnel at the Hospital will be in top condition. Nurses are expected to provide good service. This research aims to develop a subjective workload assessment technique model as an effort to improve the performance of nurses in the Inpatient Room at Royal Prima Hospital. This research is a quantitative study with a cross sectional study design which was carried out in the inpatient ward of the Royal Prima Hospital from June to July 2023. The population was 120 people. Respondents who were selected (inclusion) or excluded through the selection process were those who had more than 3 months of experience working in a care unit or related work. Data were analyzed univariate, bivariate and multivariate. The results of the research show that there is an influence of time pressure, working hour schedules, multiple roles, revetitive action on improving the performance of inpatient nursing personnel which is subjectively reasoned by inpatient nurses at Royal Prima Hospital. The variable that has the most dominant influence is the dual role variable.The suggestion of this research is that the health service should provide input in the context of continuous guidance to hospitals, especially in managing hospital management to improve better performance.

The effects of increased mental workload of air traffic controllers on time perception: Behavioral and physiological evidence

Research has shown that timing is modulated by mental workload, making duration judgments a measure of cognitive demand, alongside subjective assessments, and physiological measurements. Yet, it is unclear whether such findings can be extended in less controlled setups. By employing air traffic controllers in a real aviation environment, we tested whether tasks with different levels of cognitive load can affect their timing behavior. Participants completed temporal production, verbal estimation, and passage of time judgments, while actively engaging in real flight control sessions. Subjective assessments of task demands, as well as physiological responses (cardiac and electrodermal activity) were also measured. Accuracy of the produced intervals was measured at two distinct phases of the flight (during low-load cruising vs. high-load landing) and under two different task load manipulations (controlling one vs. two helicopters and speaking in native vs. non-native language). Analysis of interval production accuracy showed that during the high-load landing phase significant overproductions were made, compared to the low-load cruising phase, and landing two helicopters led to greater overproductions compared to landing only one. The duration of the two-helicopter sessions was significantly overestimated compared to the single-helicopter ones, and the passage of time was felt significantly faster. Subjective assessments of workload were positively correlated with the temporal estimations and passage of time judgments, and skin responses were positively correlated with the produced intervals. Overall, our results are consistent with past research, suggesting that mental workload modulates time perception in complex, real-world environments, thus making timing behavior a reliable index of the workload changes.

Analysis of Physical and Mental Workload on Emergency Department (ED) Nurses with Subjective Workload Assessment Technique (SWAT) and Cardiovascular Load (CVL) Methods (Case Study of Sidoarjo City Hospital)

Analysis of Physical and Mental Workload on Emergency Department (ED) Nurses with Subjective Workload Assessment Technique (SWAT) and Cardiovascular Load (CVL) Methods (Case Study of Sidoarjo City Hospital)

Analysis of the Effect of Working Hours on Mental Workload Using the Subjective Workload Assessment Technique Method

This research contains a study of the effect of working hours on mental workload using the Subjective Workload Assessment Technique (SWAT) method. Workload is a consequence of activities given to workers, worker activities can basically be distinguished between physical activities and mental activities. In practice, the workload encountered is a combination of physical workload and mental workload. This study aims to measure mental workload at 10 work stations in the production section at PT Berlian Eka Sakti Tangguh. The SWAT method is a subjective mental workload measurement method based on workers' perceptions. The dimensions are time load, mental effort load and psychological pressure load. The results of the calculation of workload based on SWAT found that the workload category of workers in the production section is at a moderate and high level. The highest workload was experienced at the palm oil storage station (5 workers) at 83.71%. The lowest workload was experienced at the stewing station (3 workers) at 27.36%.

Development and validation of a task load index for process control room operators (PCRO-TLX)

Process control room operators (PCRO) perform a range of complex cognitive safety-critical tasks. The aim of this exploratory sequential mixed methods study was to develop an occupation specific tool to measure the task load of PCRO using NASA Task Load Index (TLX) methodology. Participants were 30 human factors experts and 146 PCRO at two refinery complexes in Iran. Dimensions were developed via a cognitive task analysis, a research review, and three expert panels. Six dimensions were identified: perceptual demand, performance, mental demand, time pressure, effort, and stress. Data from 120 PCRO confirmed that the developed PCRO-TLX has acceptable psychometric properties, and a comparison with the NASA-TLX confirmed that perceptual, not physical, demand was relevant for measuring workload in PCRO. There was a positive convergence of scores of the Subjective Workload Assessment Technique and the PCRO-TLX. This reliable tool (α = 0.83) is recommended for risk assessing the task load of PCRO. Practitioner summary: There are benefits of having a specific tool to measure task load in safety critical roles. Thus, we developed and validated an easy-to-use targeted tool, the PCRO-TLX, for process control room operatives. Timely use and response will assure optimal production alongside health and safety in an organisation. Abbreviations: PCRO: process control room operator; TLX: task load index; PCRO-TLX: process control room operator task load index; NASA-TLX: National Aeronautics and Space Administration task load index; SWAT: subjective workload assessment technique; DALI: driving activity load index; SURG-TLX: surgery task load index; SIM-TLX: virtual reality simulation task load index; VACP: visual, auditory, cognitive and psychomotor; CVI: content validity index; CVR: content validity ratio; RMSEA: root mean square of error approximation; GFI: goodness of fit index; AGFI: adjusted goodness of fit index; CFI: comparative fit index; ANOVA: analysis of variance; CI: confidence interval

Characterising Psycho-Physiological Responses and Relationships during a Military Field Training Exercise.

Sixty-two Combat Engineer trainees (59 male, 3 female; age: 25.2 ± 7.2 years) wore an ActiGraph GT9X to monitor daily energy expenditure, physical activity, and sleep. Rating of perceived exertion (RPE), sleep quality, and fatigue were measured daily, subjective well-being was reported days 1, 5, 9, 13 and 15. Multi-level models were used for the analysis. Well-being was affected by a combination of variables including workload, subjective sleep quality, sleep duration, and sleep efficiency. RPE and subjective sleep quality were consistently significant parameters within the models of best fit. Perceptions of well-being were lower during the field training when physical workload increased, and sleep decreased. Energy expenditure was comparatively low, while daily sleep duration was consistent with field training literature. Subjective assessments of workload and sleep quality were consistently effective in explaining variations in well-being and represent an efficient approach to monitor training status of personnel.

Chinese handwriting while driving: Effects of handwritten box size on in-vehicle information systems usability and driver distraction

Objective Handwritten box size (HBS) is an essential Chinese handwriting interface element when interacting with touchscreen-based in-vehicle information systems (IVISs) since it is compactly bound up with driver distraction besides usability issues. Miscellaneous HBSs are commercially available on IVISs, yet the details of how the drivers interact with them in an in-vehicle display situation remain sparsely examined. Therefore, this study set out to investigate the effects of HBS on IVISs usability (task completion time, number of errors, number of protruding strokes, and NASA-TLX, a subjective workload assessment tool) and driver distraction (mean speed, lane position variation, total glance time, number of glances, mean glance time, and number of glances exceeding 1.6 s). Ultimately, the appropriate HBS on IVISs is determined. Methods A simulated driving experiment involving thirty drivers was launched. The primary task was lane-keeping with speed ranging from 40 to 60 km/h, and the secondary task was entering a 5-character text by Chinese handwriting input under five different HBS conditions: 25 × 25 mm, 30 × 30 mm, 35 × 35 mm, 40 × 40 mm, and 45 × 45 mm. A battery of one-way repeated measure analyses of variance (r-ANOVA) was used to examine which HBS can maximize IVISs usability and minimize driver distraction with the smallest HBS. Results Generally, the issues of IVISs usability and driver distraction improved progressively as the HBS increased to a specific size (40 × 40 mm in this study), at which they got to the asymptotes. Specifically, HBS below 40 × 40 mm was associated with longer text input time, more errors and protruding strokes, extended eyes-off-road time, excessive off-road glances, and deteriorative lateral driving performance. Nevertheless, there were no significant differences in mean glance time and longitudinal driving performance. No improvement measures were observed for HBS above 40 × 40 mm, except for a higher perceived workload. Conclusions Overall, the appropriate HBS of in-vehicle Chinese handwriting was found to be 40 × 40 mm. Considering that the in-vehicle human-machine interface (HMI) has limited display space and increasing visual complexity, these findings may help develop evidence-based design guidelines for driver-friendly IVISs and prevent distracted-related traffic injuries.

Analysis of the Influence of Mental Workload on Employee Performance with the Subjective Workload Assessment Technique (SWAT) Method at PT. Bumi Jasa Utama (Kalla Group)

Purpose: This study aimed to measure the mental workload experienced by employees in the finance department and to analyze the effect of mental workload on employee performance.
 Design/methodology/approach: This study used the Subjective Workload Assessment Technique (SWAT) method to measure the mental workload faced by employees who must perform various activities in their work.
 Findings: The results of this study indicate that the time load factor (T) is the dominant factor affecting employee workload because employees are required in terms of time to perform each activity included in the work process quickly, precisely, and in large quantities every day. Mental workload has a direct and significant positive effect on employee performance.
 Research limitations/implications: Data collection was only conducted on employees of the Finance Department of PT Bumi Jasa Utama.
 Practical implications: Based on the results of this study, the company is expected to increase the number of employees in the finance department to streamline time and minimize the workload of each employee in the finance department. The company is also expected to improve service and service quality by considering employee comfort and performance.
 Originality/value: The condition of employees who are given a high workload and ongoing causes stress and anxiety, so it is necessary to measure mental workload and the effect of mental workload on employee performance.

Gaze Motion and Subjective Workload Assessment While Performing a Task Walking Hand in Hand with a Mobile Robot

Gaze Motion and Subjective Workload Assessment While Performing a Task Walking Hand in Hand with a Mobile Robot

Develop a Comprehensive Method to Evaluate the Mental Workload of Ship Operators

Mental workload has become an important factor affecting the human error of ship operators. Controlling the mental workload of operators within a reasonable range can reduce human errors. The purpose of this study is to develop an evaluation method to evaluate the ship operator’s mental workload. First, the evaluation indices system was constructed according to three types of mental workload measurements. Second, the criteria importance though intercrieria correlation (CRITIC) method and analytic hierarchy process (AHP) method were used to determine the relative weight of each index. Finally, the fuzzy theory was used to calculate ship operator’s mental workload. The experiment results indicated that subjective workload assessment technique, physiological measurement (eye response), and error rate can be integrated into the comprehensive evaluation method to assess the mental workload of ship operators. Thus, this method can be used to comprehensively evaluate the mental workload level and improve the reliability of the assessment results.

Repeated assessments and predictors of nurses' shift-specific perceived workload.

Workload perception is of interest to researchers and policymakers as it captures subjective assessments of nurses' workload which has implications for staffing and patient outcomes. We aimed to describe repeated assessments of nurses' perceived workload among registered nurses (RNs) in day and night shifts and to examine the association of perceived workload with workdays, units, and nurse-staffing. Repeated data on the indictors of interest were collected from 90 RNs across 91 shifts in a Lebanese acute-care hospital. Perceived workload was assessed using the NASA-Task-Load Index (NASA-TLX). Linear mixed-effect models were used for analysis. Mean perceived workload was high reaching 6.63 (95% confidence interval [CI] = 6.34, 6.92) in day and 5.90 (95% CI = 5.43, 6.36) in night shifts. In mixed-effect models, perceived workload was lower on weekends/holidays as compared to weekdays in day (ß = -.32; 95% CI = -0.53, -0.12) and night (ß = -.46; 95% CI = -0.85, -0.07) shifts. Higher perceived workload (ß = .19; 95% CI = 0.04, 0.33) was associated with higher patient-to-nurse ratio in the day but not night shifts. Repeated workload assessments support the presence of elevated perceived workload among RNs which is related to weekdays and higher patient-to-nurse ratio. Future investigations would benefit from better characterization of workload particularities to address perceived burden and improve organizational and management decisions.

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.

Using augmented reality to reduce workload in offshore environments

In the offshore environment helicopters are widely used to transport crew and material from and to maritime wind farms. Due to unforeseeable and often inclement weather situations and challenging tasks these missions put a high workload on the helicopter pilots. In this paper two test campaigns are described which assess the utility of an affordable commercial-off-the-shelf (COTS) head-mounted display (HMD) to reduce workload for commercial maritime operations. The HMD system was implemented within the air vehicle simulator (AVES) at the German Aerospace Center (DLR). Three missions were flown with experienced offshore pilots, performed in a realistic scenario. Independent subjective assessments of both workload and situational awareness were obtained. Results from the studies show that the overall workload for all missions decreased and situational awareness increased when using the HMD. Opinions regarding overall benefit and advantages of the system were found to vary between pilots and missions.

An Empirical and Subjective Model of Upper Extremity Fatigue Under Hypogravity.

In the context of extra-terrestrial missions, the effects of hypogravity (0 < G < 1) on the human body can reduce the well-being of the crew, cause musculoskeletal problems and affect their ability to perform tasks, especially during long-term missions. To date, studies of the effects of hypogravity on human movement are limited to experiments on the lower limbs. Here, we extend the knowledge base to the upper limbs, by conducting experiments to evaluate the effect of hypogravity on upper limb physical fatigue and mental workload in participants. Our hypothesis was that hypogravity would both increase participant productivity, by reducing overall physical fatigue expressed in Endurance Time, and reduce mental workload. Task Intensity-Endurance time curves are developed especially in seated positions, while performing static, dynamic, repetitive tasks. This experiment involved 32 healthy participants without chronic problems of the musculoskeletal system aged 33.59 ± 8.16 years. Using the collected data, fatigue models were constructed for tasks of varying Intensity. In addition, all participants completed the NASA – Task Load Index subjective mental workload assessment, which revealed the level of subjective workload when executing different tasks. We found two trends in the empirical fatigue models associated with the difference between the strength capabilities of males and females. The first is a significant positive (p = 0.002) relation between Endurance time and gravity level (⅙ G Moon, ⅓ G Mars, 1G) with negative coefficient for males and females for a static task. And there is marginal relation (p < 0.1) between overall mental workload and gravity level with a positive coefficient for males and females for the same task. The same trend was observed for dynamic and repetitive tasks. We concluded that the Task Intensity-Endurance Time model, adapted to hypogravity in combination with subjective mental assessment, is useful to human fatigue investigation. The combination of these methods used for ergonomic analysis and digital human modeling, could improve worker productivity. Finally, this study may help prepare astronauts for long-term missions on the Moon and Mars and improve our understanding of how we can prevent musculoskeletal disorders caused by hazardous manual handling under such extreme environments.

Measurement of student mental workload during online learning using Continuous Subjective Workload Assessment Technique (C-SWAT)

The covid-19 pandemic have effect in Indonesia both financial and non-financial sector include education. There is new habit on education system such as online learning. Since online learning student use gadget/computer to learn. Using gadget in high frequencies may cause effect. This research to measure mental workload of student during online learning in Mechanical Engineering Education Department. Mental effort is measured use continuous subjective workload assessment technique. Continuous subjective workload assessment technique (C-SWAT) is simplify of subjective workload assessment technique. In continuous subjective workload assessment technique, participant is asked dimension that participant prefer, after that participant is asked to do simple arithmetic test. Dimensions are time load, mental effort and psychology-effort. This research use minimum weight of 0 (W0) with weight used is 1/3. Moreover, there is questionnaire to know study interest of participant during online learning. In this research mental effort load is the second highest score, the first highest score is psychology stress effort. Multiplication test is high score than other arithmetic test. During online school student have fatigue, most of them feel eyestrain and body sore. Student prefer synchronous learning type than a-synchronous learning it’s because in synchronous learning student can discus with teacher directly.

A field study of mental workload: conventional bus drivers versus bus rapid transit drivers

Road traffic accidents are increasing worldwide and cause a high number of fatalities and injuries. Mental Work Load (MWL) is a contributing factor in road safety. The primary aim of this work was to study important MWL factors and then compare conventional and BRT (Bus Rapid Transit) drivers' MWL. This study evaluated bus drivers' MWL using the Driving Activity Load Index (DALI) questionnaire conducted with 123 bus drivers in Tehran. The results revealed significant differences between conventional and BRT drivers' mental workload. Moreover, data modelling showed that some organisational and environmental factors such as bus type, working hours per day, road maze, and route traffic volume contribute to drivers' mental workload. These findings suggest some essential customised factors that may help measure and offer practical solutions for decreasing the level of bus drivers' MWL in real-world road driving. Practitioner summary Mental workload is affected by several contributing factors. Depending on the working context, some of these contributing factors have a more significant influence on the level of the experienced MWL. Therefore, the main factors influencing the MWL of BRT and conventional bus drivers were assessed in their real-life environment. Abbreviations: MWL: mental work load; BRT: bus rapid transit; CB: conventional bus; DALI: driving activity load index; NASA-TLX: NASA task load index; SWAT: subjective workload assessment technique; EEG: electroencephalography electrocardiogram; fNIRS: functional magnetic resonance imaging; ITS: intelligent transportation systems; AVL: automated vehicle location

A Framework to Assess Alarm Fatigue Indicators in Critical Care Staff.

OBJECTIVES:This article examines work-related and Personality personality factors that could influence health providers in experiencing alarm fatigue. The purpose of this study is to provide a basis to determine factors that may predict the potential of alarm fatigue in critical care staff.DESIGN:A questionnaire-based survey and an observational study were conducted to assess factors that could contribute to indicators of alarm fatigue.INTERVENTIONS:Factors included patient-to-staff ratio, criticality of the alarm, priority of different tasks, and personality traits.SETTING:The study was conducted at an eight-bed ICU in a mid-size hospital in Montana.SUBJECTS:Data were collected for six day shifts and six night shifts involving 24 critical care professionals. Within each 12-hour shift, six 15-minute intervals were randomly generated through work sampling for 6 days; a total of 1,080 observations were collected.MEASUREMENTS:Alarm fatigue was assessed with the subjective workload assessment technique and Boredom, Apathy, and Distrust Affects, which were measured through validated questionnaires. The Big Five Personality model was used to assess personality traits.MAIN RESULTS:Work factors including task prioritization, nurse-to-patient ratio, and length of shifts were associated with indicators of alarm fatigue. Personality traits of openness, conscientiousness, and neuroticism were also associated.CONCLUSIONS:We recommend assessing personality traits for critical care staff to be aware of how their individualities can affect their behavior towards alarm fatigue. We also recommend an examination of alternative strategies to reduce alarm fatigue, including examining the use of breaks, work rotation, or shift reduction.