Measures Of Mental Workload Research Articles

Development and validation of a behavioural video coding scheme for detecting mental workload in manual assembly

Manual assembly in the future Industry 4.0 workplace will put high demands on operators’ cognitive processing. The development of mental workload (MWL) measures therefore looms large. Physiological gauges such as electroencephalography (EEG) show promising possibilities, but still lack sufficient reliability when applied in the field. This study presents an alternative measure with a substantial ecological validity. First, we developed a behavioural video coding scheme identifying 11 assembly behaviours potentially revealing MWL being too high. Subsequently, we explored its validity by analysing videos of 24 participants performing a high and a low complexity assembly. Results showed that five of the behaviours identified, such as freezing and the amount of part rotations, significantly differed in occurrence and/or duration between the two conditions. The study hereby proposes a novel and naturalistic method that could help practitioners to map and redesign critical assembly phases, and researchers to enrich validation of MWL-measures through measurement triangulation. Practitioner summary: Current physiological mental workload (MWL) measures still lack sufficient reliability when applied in the field. Therefore, we identified several observable assembly behaviours that could reveal MWL being too high. The results propose a method to map MWL by observing specific assembly behaviours such as freezing and rotating parts. Abbreviations: MWL: mental workload; EEG: electroencephalography; fNIRS: functional near infrared spectroscopy; AOI: area of interest; SMI: SensoMotoric Instruments, ETG: Eye-Tracking Glasses; FPS: frames per second; BORIS: Behavioral Observation Research Interactive Software; IRR: inter-rater reliability; SWAT: Subjective Workload Assessment Technique; NASA-TLX: National Aeronautics and Space Administration Task Load Index; EL: emotional load; DSSQ: Dundee Stress State Questionnaire; PHL: physical load; SBO: Strategisch Basis Onderzoek

Psikososial dan Beban Kerja Perawat – Sebuah Penelitian di Salah Satu RS Militer di Indonesia

Penelitian ini bertujuan untuk mengetahui tingkat beban kerja mental dan faktor psikososial dari para perawat tingkat pelaksana di ruang rawat inap rumah sakit militer. Data diambil dari penyebaran kuesioner kepada 41 perawat tingkat pelaksana yang bertugas di ruang rawat inap. Pengukuran beban kerja mental dilakukan dengan menggunakan kuesioner National Aeronautics and Space Administration – Task-Load Index (Nasa–TLX). Pengukuran faktor psikososial dilakukan dengan menggunakan kuesioner The Copenhagen Psychosocial Questionnaire (COPSOQ II). Hasil penelitian menunjukkan bahwa nilai rerata keseluruhan beban kerja mental berada pada kategori tinggi. Nilai faktor psikososial lingkungan kerja menunjukkan hasil yang baik pada mayoritas skala penilaian. Akan tetapi, pihak rumah sakit perlu memperhatikan beberapa faktor seperti tuntutan emosi, persepsi kesehatan, kelelahan dan stres serta aspek tempo pekerjaan. Hasil penelitian ini juga menunjukkan adanya hubungan positif yang kuat dan signifikan antara dimensi kepercayaan manajemen dengan kinerja dengan r=0,545 (p=0,000). Dengan demikian, disarankan agar pihak manajemen rumah sakit tidak hanya melakukan penilaian terhadap kinerja para perawat tetapi dapat juga melakukan penilaian beban kerja mental dan faktor psikososial secara berkala agar tercipta lingkungan kerja yang kondusif

Stretching Interventions and Their Effect on Mental the Workload

Cleaning workers are jobs that require physical strength especially if the work is carried out at a height, and it is not uncommon to complain about musculoskeletal discomfort in physical areas that feel uncomfortable when working in an un ergonomic position. From the observation results If observed posture when cleaning wokers work, body position tilted and bent with angles ranging from 20°-60°, neck bent with an angle of about 20 °, cleaning is done repeatedly by shifting the left hand and right hand with the angle of the upper arm > 90° raised for 10 minutes and forearm around 40°, this illustrates the condition of awkward posture cleaning wokers not ergonomic, posture that is not ergonomic will cause musculoskeletal disorder. The purpose of this research is to measure the effect of stretching on mental workload in an effort to mental recovery. To achieve these objectives, first determine the type of glass cleaning activity outside the building at a height including: preparing tools, climbing stairs, cleaning glass, moving to other areas and cleaning tools, determining stretching movements, then conducting experiments in this case divided into 3 (three) treatment, first without stretching, giving stretching in the morning at 10 am for 6 minutes and stretching during the day at 2 pm for 6 minutes. Measurement of mental workload using the Subjective Workload Assessment Technique (SWAT) method, statistical processing by carrying out the covariance homogeneity test, Multivariate test and followed by the MANOVA test. The results of this research that stretching in addition to having a positive influence on the decline in mental workload, can also be used for mental recovery. Working at a height with a work posture that is not ergonomic, will increase the level of mental workload.

Employee acceptability of wearable mental workload monitoring: exploring effects of framing the goal and context in corporate communication

Development of wearable mental workload (MWL) measures thrives, especially as leveraged by Industry 4.0. When employees object to wearing such gauges; however, research efforts might end up redundant. Based on self-determination and communication theories, this study assumed that employees’ acceptability of wearable MWL-monitoring is shaped by framing characteristics in corporate communication. Specifically, we hypothesized that acceptability depends on how (1) the technology’s goals and (2) context of implementation is framed. A pilot study (N = 150) revealed that framing wearable MWL-monitoring in terms of serving intrinsic goals (e.g., improving health) in an autonomy-supportive context (e.g., allowing discussion) induced a higher employee acceptability, compared to framing the technology in terms of serving extrinsic goals (e.g., increasing productivity) in a controlling context (e.g., mandating use). A subsequent pre-registered study (N = 350) could, however, not replicate this result. Instead, higher acceptability was associated with higher technology readiness, lower education levels, and being a woman (for the trust component of acceptability). Independent of conditions, mean acceptability, interestingly, panned out neutral. The current work is thereby the first exploring the complexities of employee acceptability of wearable MWL-monitoring and, based on open-ended questions, finally suggests that privacy management might be the most pivotal explanatory variable.

Measurement and identification of mental workload during simulated computer tasks with multimodal methods and machine learning

This study attempted to multimodally measure mental workload and validate indicators for estimating mental workload. A simulated computer work composed of mental arithmetic tasks with different levels of difficulty was designed and used in the experiment to measure physiological signals (heart rate, heart rate variability, electromyography, electrodermal activity, and respiration), subjective ratings of mental workload (the NASA Task Load Index), and task performance. The indices from electrodermal activity and respiration had a significant increment as task difficulty increased. There were no significant differences between the average heart rate and the low-frequency/high-frequency ratio among tasks. The classification of mental workload using combined indices as inputs showed that classification models combining physiological signals and task performance can reach satisfying accuracy at 96.4% and an accuracy of 78.3% when only using physiological indices as inputs. The present study also showed that ECG and EDA signals have good discriminating power for mental workload detection. Practitioner summary: The methods used in this study could be applied to office workers, and the findings provide preliminary support and theoretical exploration for follow-up early mental workload detection systems, whose implementation in the real world could beneficially impact worker health and company efficiency. Abbreviations: NASA-TLX: the national aeronautics and space administration-task load index; ECG: electrocardiographic; EDA: electrodermal activity; EEG: electroencephalogram; LDA: linear discriminant analysis; SVM: support vector machine; KNN: k-nearest neighbor; ANNs: artificial neural networks; EMG: electromyography; PPG: photoplethysmography; SD: standard deviation; BMI: body mass index; DSSQ: dundee stress state questionnaire; ANOVA: analysis of variance; SC: skin conductance; RMS: root mean square; AVHR: the average heart rate; HR: heart rate; LF/HF: the ratio between the low frequencies band and the high frequency band; PSD: power spectral density; MF: median frequency; HRV: heart rate variability; BPNN: backpropagation neural network

A Neuroergonomics Approach to Mental Workload, Engagement and Human Performance.

The assessment and prediction of cognitive performance is a key issue for any discipline concerned with human operators in the context of safety-critical behavior. Most of the research has focused on the measurement of mental workload but this construct remains difficult to operationalize despite decades of research on the topic. Recent advances in Neuroergonomics have expanded our understanding of neurocognitive processes across different operational domains. We provide a framework to disentangle those neural mechanisms that underpin the relationship between task demand, arousal, mental workload and human performance. This approach advocates targeting those specific mental states that precede a reduction of performance efficacy. A number of undesirable neurocognitive states (mind wandering, effort withdrawal, perseveration, inattentional phenomena) are identified and mapped within a two-dimensional conceptual space encompassing task engagement and arousal. We argue that monitoring the prefrontal cortex and its deactivation can index a generic shift from a nominal operational state to an impaired one where performance is likely to degrade. Neurophysiological, physiological and behavioral markers that specifically account for these states are identified. We then propose a typology of neuroadaptive countermeasures to mitigate these undesirable mental states.

A measure of mental workload during multitasking: Using performance-based Timed Petri Nets

Multitasking is common in emergency, which will result in man-made error due to many factors such as inappropriate Mental Workload (MW). To improve the performance under multitasking, the automatic equipment or assistive systems carry out task/interface optimizations according to the MW evaluation results, and the effectiveness of these technologies depends on how to choose an appropriate MW evaluation model. This paper has developed a performance-based Timed Petri Nets (TPN) model to evaluate MW during multitasking. The concrete functioned places and transitions, were proposed to structure a human resource allocation and recovery processes in TPN. The characteristics of operator are interpreted as initial markings of places and delay of transitions. Task performance is calculated as the difference between the triggering time of two transitions and a behavior process structure, respectively. The real-time MW is quantified and expressed as the remaining percentage of tokens in the attention resource place. A case study of triple-task execution was examined for verification of the model. Furthermore, the distinguishability and stability of the model, its comparison with ACT-R, and the application in task optimization were discussed. Relevance to industryThe Timed Petri Nets-based model can analyse the influence between mental workload and system states while proposed quantitative and individualized results of mental workload, which can direct a mental workload-based task optimization in safety-critical systems under multitasking in the design phase.

Analisis Beban Kerja Fisik dan Mental Pada Operator Contact Center (Studi Kasus : PT. XYZ Samarinda)

Tuntutan perkerjaan operator contact center PT. XYZ Samarinda untuk selalu ramah kepada pelanggan dalam keadaan apapun dan harus fokus dalam bekerja kemungkinan dapat menimbulkan beban kerja mental. Selain itu operator contact center harus bekerja monoton dengan keadaan duduk di depan komputer dalam waktu 8 jam dapat saja menimbulkan beban kerja fisik. Berdasarkan permasalahan tersebut, maka dilakukan penelitian mengenai analisis beban kerja fisik dan mental pada operator contact center sehingga dapat diberikan rekomendasi perbaikan untuk meningkatkan produktivitas dan kenyamanan saat bekerja. Pengukuran beban kerja fisik dilakukan menggunakan metode pengukuran %CVL pada saat bekerja. Sedangkan pengukuran beban kerja mental dilakukan menggunakan metode NASA-TLX dengan membagikan kuesioner kepada 9 operator contact center selama 10 hari. Hasil penelitian menunjukkan bahwa rata-rata beban kerja fisik operator contact center adalah 13,5%. Hasil tersebut menunjukkan bahwa beban kerja fisik operator contact center termasuk kategori ringan yang artinya tidak terjadi pembebanan yang berarti. Sedangkan rata-rata beban kerja mental operator contact center adalah 65. Berdasarkan hasil tersebut maka nilai beban kerja mental operator contact center dalam kategori sedang. Rekomendasi perbaikan yang dapat diberikan antara lain melakukan cara duduk yang benar, melakukan perbaikan tata letak AC agar lingkungan kerja menjadi nyaman dan menggunakan kursi kerja ergonomis. Selain itu perlu dibangun hubungan yang baik yaitu dengan memahami gaya komunikasi antar pekerja agar tidak terjadi kesalahpahaman, melakukan perayaan kecil, berolahraga atau berekreasi bersama, dan mengadakan Training ESQ untuk menyeimbangkan emosi dan kecerdasan.

Mobile pupillometry in manual assembly: A pilot study exploring the wearability and external validity of a renowned mental workload lab measure

Human operators in the upcoming Industry 4.0 workplace will face accelerating job demands such as elevated cognitive complexity. Unobtrusive objective measures of mental workload (MWL) are therefore in high demand as indicated by both theory and practice. This pilot study explored the wearability and external validity of pupillometry, a MWL measure robustly validated in laboratory settings and now deployable in work settings demanding operator mobility. In an ecologically valid work environment, 21 participants performed two manual assemblies - one of low and one of high complexity - while wearing eye-tracking glasses for pupil size measurement. Results revealed that the device was perceived as fairly wearable in terms of physical and mental comfort. In terms of validity, no significant differences in mean pupil size were found between the assemblies even though subjective mental workload differed significantly. Exploratory analyses on the pupil size when attending to the assembly instructions only, were inconclusive. The present work suggests that current lab-based procedures might not be adequate yet for in-the-field mobile pupillometry. From a broader perspective, these findings also invite a more nuanced view on the current validity of lab-validated physiological MWL-measures when applied in real-life settings. We therefore conclude with some key insights for future development of mobile pupillometry.

The Influence of Monochronic/Polychronic Time Orientation on Temporal Demand and Subjective Mental Workload

The sensitivity of mental workload measures is influenced by cultural and individual factors. One individual factor that is hypothesized to influence mental workload is time orientation. The aim of this study is to observe the influence of time orientation on temporal demand and subjective mental workload. One hundred and two participants representing three different time orientations, namely monochronic, neutral, and polychronic orientations, assessed using the Modified Polychronic Attitude Index 3 (MPAI3), voluntarily participated in this study. Participants were instructed to complete a search and count task in four different conditions with varying degrees of difficulty. Mental workload was assessed using subjective (NASA-TLX) and objective (heart rate variability, or HRV) methods and analyzed for each condition. The results show that, with comparable performance and comparable HRV, monochronic participants show higher sensitivity than neutral or polychronic participants in subjective mental workload, particularly the temporal demand dimension. The implications are discussed.

Analyzing Mental Workload of Remote Worker by Using SWAT Methodology (Case Study: Remote Software Engineer)

Telecommuting or “working from home” is a new option for working systems that exists in the industrial era 4.0. Software Engineer is responsible for creating web-based applications using programming languages. Physical interaction at work is very minimal because the main key to the work of a Software Engineer is cognitive ability. Therefore, intellectual skills need to be considered as a tool for analyzing human performance. This study aims to measure the mental workload of remote workers by using SWAT method. SWAT will describe the multi-dimensional model of workload which consists of three elements, (1) Time Load, (2) Mental Effort Load, and (3) Psychological Stress Load. The objects observed were 54 Software Engineers with various fields. At first the determination of the value of mental workload was carried out, sorting 27 SWAT cards, and processing data using SWAT software. Validity and reliability tests were also conducted. From the measurement of mental workload using SWAT, it was found that 6 of 54 respondents have a maximum workload (value of 100). Development and Operations Engineer has the lowest mental workload value of 15.8.

The temptation to text when driving – Many young drivers just can't resist

When questioned, people clearly understand that texting while driving is a dangerous behaviour. However, evidence convincingly shows that a meaningful proportion continue to both read and write texts. Why is this? We prospectively recognise the risks associated with the task; yet in context, many of us are unable to restrain our behaviour for the greater good. This paper reports a simulator study investigating young drivers’ engagement with texting. It considers, (i) willingness to text, and (ii) the nature of the temptation (modest financial reward or penalty).The study had a mixed design with all Participants experiencing a ‘temptation to text’ condition (and a control). During the ‘temptation to text’ condition, half the sample were offered either the financial reward to incentivise responses, while the others had an equivalent penalty. Ultimately, all participants received full compensation. Driver performance and mental workload measures were collected as proxy indicators for behavioural impacts.Results are consistent with previous published studies and showed significantly increased workload. Similarly, vehicle performance was also found to be significantly worse when texting and driving. However, the primary goal of this study was to explore the willingness of young drivers to read and respond to mobile phone ‘texts’ when tempted to do so. Engagement with texting was found to be significantly higher than hypothesised with 60% of participants responding to text messages. Adoption of short headways was found to be predictive of an inclination to text. Socio-technical implications are considered with respect to the potential to reduce texting while driving.

ALLOCATION OF MARITIME TASK FORCE PERSONNEL UNIFIL CONTINGEN BASED ON ANALYSIS WORK LOADS

The workload of an organization is related to the efficient and effective utilization of human resources so that it can realize the vision, mission and objectives of the organization. Various methods are used to optimize the number of personnel in an organization, so that each task can be completed effectively and efficiently. KRI Diponegoro-365 personnel as the TNI Maritime Task Force, the Garuda Contingent can not be separated from the problems regarding the lack of conformity to workload with the allocation of the number of available personnel. To overcome this, an analysis of workload measurement is needed which can then be used for determine the allocation of the right number of personnel needed in each division. This study uses the measurement of NASA-TLX mental workload and physical workload according to TNI Roles. Both of these methods are then compared between mental and physical burden that occurs. From the results of the comparison, it was found that physical workload is needed in the completion of tasks in each division. After a comparison, then the determination of the allocation of the number of personnel will be carried out using the physical workload approach based on the description of the tasks in each division. The results of the calculation will then show the division that has excess or lack of personnel. The overall results obtained from this study can be concluded that the number of maritime task force personnel using the Diponegoro class KRI is appropriate, but the allocation of personnel in each division needs to adjust to the existing workload.
 Keywords: Workload, NASA-TLX (Task Load Index), Number of Military Personnel

Cerebral cortical networking for mental workload assessment under various demands during dual-task walking.

While several studies have examined attentional reserve (via event-related potentials) and mental effort (via EEG spectral content) from various cortical regions during dual-task walking, none have assessed changes in the magnitude of interregional (cortico-cortical) communication as a measure of mental workload. Therefore, by deploying a traditional montage of electrode sites centered over the motor planning region as well as a more comprehensive graph theory-based approach encompassing the entire scalp, this study aimed to systematically examine changes in the magnitude of functional connectivity underlying cortico-cortical communication to assess changes in mental workload under various levels of challenge. Specifically, the Weighted Phase Lag Index (WPLI) was computed to assess the changes in magnitude of functional connectivity as participants performed a cognitive task under two demands (low and high) and two conditions (seated and walking). The results revealed enhanced fronto-centro-temporo-parietal theta connectivity during dual-task walking relative to being seated as well as a reduced inhibition of fronto-centro-temporo-parieto-occipital alpha networking as the demand on the secondary cognitive task increased. Collectively, these findings may reflect greater recruitment of task relevant processes to respond to increased cognitive-motor demands and thus an elevation of mental workload in an effort to maintain performance under varying levels of challenge. This work has the potential to inform future mental workload assessment applications in patient populations, including those who employ prostheses during cognitive-motor performance under various taskdemands.

2D3-2 Quantification of the subsidiary task difficulty for mental workload measurement by dual-task method

2D3-2 Quantification of the subsidiary task difficulty for mental workload measurement by dual-task method

Do surgeon non-technical skills correlate with teamwork-related outcomes during robot-assisted surgery?

IntroductionTo evaluate the impact of non-technical skills (NTS) on team performance, workload and clinical outcomes.MethodsThe operating room (OR) environment of 20 robot-assisted radical prostatectomies performed by three different surgeons was...

Investigating the effect of indoor thermal environment on occupants’ mental workload and task performance using electroencephalogram

Workers' performance in indoor offices can be greatly affected by the thermal condition of the environment. However, this effect can be difficult to quantify, especially when the thermal stress is a moderate increase or decrease in temperature and the work productivity cannot be directly measured. Subjects' high motivation to perform well under experimental conditions also causes difficulties in comparing their performance in different thermal environments. In order to overcome these limitations, this paper proposes a method to investigate the effect of the indoor thermal conditions on occupants' performance by studying occupants' mental workload measured by the electroencephalography (EEG) when they perform standardized cognitive tasks. An experiment integrating EEG mental workload measurement and cognitive tasks was implemented on 15 subjects. EEG data were collected while subjects were performing four cognitive tasks on computers. Based on previous studies, we propose a mental workload index calculated from the frontal theta and parietal alpha frequency band power. Within-subject comparisons were performed to investigate whether subjects' mental workload is statistically different under three different thermal environments, representing thermal sensations of slightly cool, neutral, and slightly warm. The results show that the effect of thermal environment varies across different individuals. By comparing the mental workload index among different thermal environments, we found that the slightly warm environment resulted in a relatively higher mental workload than the other two environments to achieve the same performance. The study provides promising insights into how the thermal environment influences occupants’ performance by affecting their mental workload from the neurophysiological perspective.

ANALYSIS OF DETERMINATION THE NUMBER PERSONNEL BASED ON WORKLOAD ACCORDING TO JOB DESCRIPTION (STUDY CASE IN ACCOUNTING INSTITUTIONS)

The workload is highly related to efficient and effective human resource utilization in an organization to achieve organizational objectives, vision, and mission. Various methods are used to optimize the number of personnel in an organization so that each task can be completed quickly and precisely. Accounting Institutions are inseparable from problems regarding the lack of workload with the number of personnel working on it. The change of the Policy gives an impact on the change of Job Description and List of Personnel Arrangements of the organization. To overcome these issues, workload measurement, analysis can be used to determine the optimal amount of personnel required in their working units. This study uses a mental workload measurement so called NASA-TLX and physical workload measurement According to the applicable workload regulation that is in accordance with the Administrative Direction of Workload Analysis. Both methods are then carried out to be compared to each other. The results showed that the physical workload is required in the completion of tasks in each work unit. In addition, the determination of the optimal number of personnel using physical workload or appropriate tasks per task position based Job Description is performed. As a result, it is known that there is an excessive workload in the Sub Service Budget Cost work units with personal shortcomings. On the other hand, there is an excessive personnel number in Administrative Work, Sub Department of Finance Administration and Sub Department Financial Control. The overall conclusion of this study is a need for personnel reduction in a List of Personnel Arrangements currently known as Accounting Institutions to be 39 personnel instead of the existing 48 personnel. 
 Keywords: Workload, NASA-TLX (Task Load Index), assignments Per Task title, Number of Optimal personnel

Comparison of NASA-TLX scale, modified Cooper–Harper scale and mean inter-beat interval as measures of pilot mental workload during simulated flight tasks

The sensitivity of NASA-TLX scale, modified Cooper–Harper (MCH) scale and the mean inter-beat interval (IBI) of successive heart beats, as measures of pilot mental workload (MWL), were evaluated in a flight training device (FTD). Operational F/A-18C pilots flew instrument approaches with varying task loads. Pilots’ performance, subjective MWL ratings and IBI were measured. Based on the pilots’ performance, three performance categories were formed; high-, medium- and low-performance. Values of the subjective rating scales and IBI were compared between categories. It was found that all measures were able to differentiate most task conditions and there was a strong, positive correlation between NASA-TLX and MCH scale. An explicit link between IBI, NASA-TLX, MCH and performance was demonstrated. While NASA-TLX, MCH and IBI have all been previously used to measure MWL, this study is the first one to investigate their association in a modern FTD, using a realistic flying mission and operational pilots.Practitioner summary: NASA-TLX scale, MCH scale and the IBI were evaluated in a flight training device. All measures were able to differentiate most task conditions and there was a positive correlation between NASA-TLX and MCH scale. An explicit link between IBI, NASA-TLX, MCH and performance was demonstrated.Abbreviations: ANOVA: Analysis of Variance; ECG: Electrocardiograph; F/A: fighter/attack; ft: feet; FTD: flight training device; G: Gravity; km: kilometer; m: meter; m/s: meters per second; MWL: mental workload; MCH: modified cooper-harper; NASA-TLX: NASA Task Load Index; NM: Nautical Mile; NN: normal-to-normal; IBI: inter-beat interval; ILS: Instrument Landing System; RR: R-Wave to R-Wave; SD: standard deviation; TTP: tactics, techniques and procedures; WTSAT: Weapon Tactics and Situation Awareness Trainer

Dissociation Between Mental Workload, Performance, and Task Awareness in Pilots of High Performance Aircraft

The purpose of this study was to demonstrate how the inclusion of a tactical task goal awareness measure complemented mental workload and performance measures in a simulated air combat mission. It was hypothesized that the evaluation of the tactical task goal awareness could provide additional information concerning the cognitive demands a pilot is exposed to during a complex air combat task. A test setting was developed to test this hypothesis in a virtual flight training device. To highlight the impact of task complexity, high performance aircraft pilots' heart rate (HR), interbeat-interval (IBI), and performance in two simple flying tasks were first compared. Then, a similar comparison, complemented with the tactical task goal awareness measure, was made with two complex flying tasks. It was found that when the pilot's awareness of the tactical goals was low, a combination of low performance and low mental workload occurred. It was concluded that when the pilots' performance is evaluated on a complex air combat task, the awareness of the tactical goals, performance, and mental workload should be studied together as the pilot's awareness can explain some of HR/IBI responses that could be otherwise misinterpreted. More generally, mental workload, performance, and task goal awareness should all be considered when the operator's performance in any complex human-machine system is assessed.