Why measure mental workload

More recently, studies of workload have also become of interest to researchers in the fields of media and communications, human-machine interaction, medical simulation and training, behavioral economics and finance. With so many potential applications, there is no universal solution to studying mental workload, and no single standard method that is recommended.

Luckily, there is a large body of literature describing mental workload from multiple angles and using many different tools, but this can be almost overwhelming. With so many choices, which is the right combination of sensors for you? Mental workload research remains immensely valuable for many current disciplines, and is poised to become an important variable in new and emerging fields.

While advances in machine learning and artificial intelligence will continue to inform an understanding of human behavior and interactions in different settings, this work will require a solid foundation built on validations of mental workload. State of Science: Mental Workload in Ergonomics.

Ergonomics , 58 1 Review and reappraisal of modelling and predicting mental workload in single- and multi-task environments. Stress , 14 1 , 74— Mental Workload: its Theory and Measurement.

Plenum Press, New York. Impact of incremental increases in cognitive workload on physiological arousal and performance in Young adult drivers. Transport Res. J Physiol Anthropol , 27 4 : Using galvanic skin response for cognitive load measurement in arithmetic and reading tasks. Electrophysiological, behavioral, and subjective indexes of workload when performing multiple tasks: manipulations of task difficulty and training. An analysis of mental workload in pilots during flight using multiple psychophysiological measures.

Aviation, Space, and Environmental Medicine , 78 5 , In Hancock, Peter A. Human Mental Workload. Advances in Psychology.

Amsterdam: North Holland. ISBN The traffic control center stressors caused changes in heart rate variability features and EMG amplitude, although the average workload score was significantly higher in HTD conditions than in LTD conditions. The results suggested that when operators' workload increases, their mental fatigue and stress level increase and their mental health deteriorate. Therefore, it maybe necessary to implement an ergonomic program to manage mental health.

Furthermore, by evaluating mental workload , the traffic control center director can organize the center's traffic congestion operators to sustain the appropriate mental workload and improve traffic control management.

Investigation of relation between operator's mental workload and information flow in accident diagnosis tasks of nuclear power plant.

As the human-machine interface in MCR is advanced, operator's information acquisition, information gathering and decision-making is becoming an important part to maintain the effective and safe operation of NPPs. Diagnostic task in complex and huge systems like NPP is the most difficult and mental effort-demanding for operators. This research investigates the relation between operator's mental workload and information flow in accident diagnosis tasks. The amount of information flow is quantified, using information flow model and Conant's model, a kind of information theory.

For the mental workload measure , eye blink rate, blink duration, fixation time, number of fixation, and gaze direction are measured during accident diagnosis tasks. It is shown that the operator's mental workload has significant relation to information flow of diagnosis task. It makes possible to predict the mental workload through the quantity of the information flow of a system. Pilot workload evaluated with subjective and physiological measures. The aim of the present study is to validate different measures for mental workload.

Ten aspirant fighter jet pilots flew several scenarios in a flight simulator. The scenarios were divided into segments with different levels of task load.

During the flight, heart rate, respiration and blood pressure. EEG correlates of task engagement and mental workload in vigilance, learning, and memory tasks.

The ability to continuously and unobtrusively monitor levels of task engagement and mental workload in an operational environment could be useful in identifying more accurate and efficient methods for humans to interact with technology. This information could also be used to optimize the design of safer, more efficient work environments that increase motivation and productivity.

The present study explored the feasibility of monitoring electroencephalo-graphic EEG indices of engagement and workload acquired unobtrusively and quantified during performance of cognitive tests.

Across participants, engagement but not workload decreased over the min vigilance test. Workload but not engagement increased linearly as level of difficulty increased in forward and backward-digit-span, grid-recall, and mental -addition tests. EEG measures correlated with both subjective and objective performance metrics. These data in combination with previous studies suggest that EEG engagement reflects information-gathering, visual processing, and allocation of attention.

EEG workload increases with increasing working memory load and during problem solving, integration of information, analytical reasoning, and may be more reflective of executive functions. Inspection of EEG on a second-by-second timescale revealed associations between workload and engagement levels when aligned with specific task events providing preliminary evidence that second.

Driving with varying secondary task levels: mental workload , behavioural effects, and task prioritization. How do drivers behave in situations with high mental workload , and do they actively prioritize.

The purpose of this scoping review was to survey the most recent 5 years acute care, community health, and mental health nursing workload literature to understand themes and research avenues that may be applicable to school nursing workload research. The search for empirical and nonempirical literature was conducted using search engines such as….

What is the relationship between mental workload factors and cognitive load types? The present study tested the hypothesis of an additive interaction between intrinsic, extraneous and germane cognitive load, by manipulating factors of mental workload assumed to have a specific effect on either type of cognitive load.

The study of cognitive load factors and their interaction is essential if we are to improve workers' wellbeing and safety at work. High cognitive load requires the individual to allocate extra resources to entering information. It is thought that this demand for extra resources may reduce processing efficiency and performance.

The present study tested the effects of three factors thought to act on either cognitive load type, i. Results revealed additive effects of task difficulty and time pressure, and a modulation by alertness on behavioral, subjective and psychophysiological workload measures. Mental overload can be the result of a combination of task-related components, but its occurrence may also depend on subject-related characteristics, including alertness.

Solutions designed to reduce incidents and accidents at work should consider work organization in addition to task constraints in so far that both these factors may interfere with mental workload. A market research company Nielsen reported that consumers in the Asia-Pacific region have become the most active group in online shopping.

Focusing on augmented reality AR , which is one of three major techniques used to change the method of shopping in the future, this study used a mixed design to discuss the influences of the method of online shopping, user gender, cognitive style, product value, and sensory channel on mental workload in virtual reality VR and AR situations.

The results showed that males' mental workloads were significantly higher than females'. For males, high-value products' mental workload was significantly higher than that of low-value products. In the VR situation, the visual mental workload of field-independent and field-dependent consumers showed a significant difference, but the difference was reduced under audio-visual conditions.

In the AR situation, the visual mental workload of field-independent and field-dependent consumers showed a significant difference, but the difference increased under audio-visual conditions.

This study provided a psychological study of online shopping with AR and VR technology with applications in the future. Based on the perspective of embodied cognition, AR online shopping may be potential focus of research and market application. For the future design of online shopping platforms and the updating of user experience, this study provides a reference.

In the VR situation, the visual mental workload of field-independent and field-dependent consumers showed a significant difference, but the difference was reduced under audio—visual conditions.

In the AR situation, the visual mental workload of field-independent and field-dependent consumers showed a significant difference, but the difference increased under audio—visual conditions.

Mental workload while driving: effects on visual search, discrimination, and decision making. The effects of mental workload on visual search and decision making were studied in real traffic conditions with 12 participants who drove an instrumented car. Mental workload was manipulated by having participants perform several mental tasks while driving. A simultaneous visual-detection and discrimination test was used as performance criteria. Mental tasks produced spatial gaze concentration and visual-detection impairment, although no tunnel vision occurred.

According to ocular behavior analysis, this impairment was due to late detection and poor identification more than to response selection. Verbal acquisition tasks were innocuous compared with production tasks, and complex conversations, whether by phone or with a passenger, are dangerous for road safety.

Multi-scale entropy analysis of VR-based analog-digital system of the operator mental workload. In the past, serious accidents of nuclear power plant usually had relation with the negligence, error handling and wrong decisions of operators. Therefore, to understand and be able to measure mental workload levels of operators are significant for safety issues in the nuclear power plant, especially when operators face emergency conditions.

Therefore, this study is to determine the physiological indicators to measure the operator in the task of mental workload.

After importing the data to calculate heart rate variability of complexity analysis, it can help us to understand the operator for the analog-digital platform adaptation. The virtual analog-digital nuclear plant control room is built using a 3D game development tool called Unity3D. Effects of electronic emergency-department whiteboards on clinicians' time distribution and mental workload.

Whiteboards are a central tool at emergency departments. With the electronic whiteboard, physicians and nurses spend more Main reasons for these changes appear to be that the electronic whiteboard facilitates better timeouts and handovers. Physicians and nurses are, however Finally, the secretaries The purpose of this study was to evaluate the rate of subjective mental workload SMWL and its correlation with musculoskeletal disorders among bank staff members in Kurdistan Province located in western Iran.

This cross-sectional study was conducted among bank staff members in Kurdistan Province, Iran. NASA-TLX is a multidimensional rating procedure that derives an overall workload score based on a weighted average of ratings on 6 subscales. The musculoskeletal disorders MSDs were documented with the Nordic Musculoskeletal Questionnaire and generic body diagram. Of the staff members, The highest frequencies of pain were in the neck and lower back. The statistical analysis of the data revealed that there was a significant correlation between the overall mental workload score and also among the 6 subscales of SMWL separately with MSDs P Evaluation of operators' mental workload of human-system interface automation in the advanced nuclear power plants.

It has been expected that the automation of certain tasks in a control room would help decrease operators' mental workload , enhance situation awareness, and improve the whole system performance. However, there have been too many automation-induced system failures that would warrant a fresh look on the influences of automation.

Automation problems include the reduction in the operator's system awareness, an increase in monitoring workload , and the degradation in manual skills. This study evaluates operators' mental workload and system performance during a human-system interface HSI automation in an advanced nuclear power plant NPP.

The reactor shutdown task and alarm reset task simulations were conducted in this study to evaluate operators' mental workload and performance. The results of this study indicated that for ensuring safe operating in NPPs, the design of automation needs to be carefully implemented. Task characteristics and degrees of automation should be carefully evaluated while designing HSIs. The reactor shutdown tasks studied in this paper suggest that a high level of automation design for the long period and low workload would be sufficient.

On the other hand, the degree of automation of alarm reset task does not show a significant difference to the operator's mental workload. In conclusion, the human-system interface automation in advanced NPPs is suggested to be more flexible and needs to be continually improved.

Assessment of mental workload and academic motivation in medical students. To investigate the level of correlation and direction of linearity between academic motivation and subjective workload. Academic motivation values were obtained with the help of Academic Motivation Scale university form. SPSS 17 was used for statistical analysis. Of the Phase 5 students, 18 Subjective workload affected academic motivation in medical students.

Mental workload and motor performance dynamics during practice of reaching movements under various levels of task difficulty. The assessment of mental workload can inform attentional resource allocation during task performance that is essential for understanding the underlying principles of human cognitive-motor behavior. Thus, this work aimed to examine mental workload by employing the NASA TLX as well as the changes in motor performance resulting from the practice of a novel reaching task.

Two groups of participants practiced a reaching task at a high and low nominal difficulty during which a group-level analysis assessed the mental workload , motor performance and motor improvement dynamics.

A secondary cluster analysis was also conducted to identify specific individual patterns of cognitive-motor responses. Overall, both group- and cluster-level analyses revealed that: i all participants improved their performance throughout motor practice, and ii an increase in mental workload was associated with a reduction of the quality of motor performance along with a slower rate of motor improvement.

The results are discussed in the context of the optimal challenge point framework and in particular it is proposed that under the experimental conditions employed here, functional task difficulty: i would possibly depend on an individuals' information processing capabilities, and ii could be indexed by the level of mental workload which, when excessively heightened can decrease the quality of performance and more generally result in delayed motor improvements.

Impact of 3D vision on mental workload and laparoscopic performance in inexperienced subjects. To assess the effect of vision in three dimensions 3D versus two dimensions 2D on mental workload and laparoscopic performance during simulation-based training.

A prospective, randomized crossover study on inexperienced students in operative laparoscopy was conducted. Forty-six candidates executed five standardized exercises on a pelvitrainer with both vision systems 3D and 2D. Laparoscopy performance was assessed using the total time in seconds and the number of failed attempts. However, some undesirable effects such as visual discomfort or headache are identified initially. Development of an objective mental workload assessment tool based on Rasmussen's skill—rule—knowledge framework.

It is important to monitor operators' mental workload during the operation phase. Physiological measurement approaches could record the operator's mental data continuously, and might be less interruptive on the work activities. However, these methods often require the attachment of physical sensors, which are not unobtrusive in the physical sense.

Furthermore, the individual difference makes calibrating to each individual tedious and requires trained persons to use. Often high noise-to-signal ratio data are hard to analyze.

Due to these factors, physiological workload measurements are hardly widely applied in practical fields. This model, developed based on the Rasmussen's skill—rule—knowledge framework, is comprised of two novel cognitive indices, the attention required index and uncertainty index.

It can be used as the basis for establishing an early online warning system automatically. Furthermore, this model also predicts the types of error-prone tasks. This kind of information is expected to provide managers and supervisors with opportunities to intervene and improve tasks before error occurred.

Finally, the predictive model proposed in this paper requires more practical application in fields to be completed. Workload , mental health and burnout indicators among female physicians. Female doctors in Hungary have worse indicators of physical and mental health compared with other professional women.

We aimed to cast light on possible indicators of mental health, workload , and burnout of female physicians. Independent samples t test or chi-squared test was used both for the two time-point comparison and the comparison between the index and the control groups. The background factors of sleep disorders and burnout were assessed by binary logistic regression analysis. No significant differences in the rates of depressive symptoms and suicidal thoughts and attempts were detected between the and cohorts, but the prevalence of sleep disorders increased.

The workload increased, and there was less job satisfaction in than in , coupled to more stressful or difficult work-related situations. The personal accomplishment component of burnout significantly decreased in line with the declining work-related satisfaction.

Compared to the professional control groups, the prevalence of depressive symptoms, suicide attempts, and sleep disorders was higher among female physicians at both time-points. The number of workplaces, frequency of work-related stressful situations, and intensive role conflict was associated with sleep disorders and decreased personal accomplishment. In comparison with the other professional groups, female doctors had worse mental health indicators with regard to depression, suicidal ideas, and sleep disorders both in and while within professional strata the changes seemed to be less.

Increasing workload had a clear impact on sleep disorders and the personal accomplishment dimension of burnout. All participants completed a consent form. Further details. Academic context and perceived mental workload of psychology students. The excessive workload of university students is an academic stressor. Consequently, it is necessary to evaluate and control the workload in education. The objectives of this study were: a to measure the workload levels of a sample of psychology students, b to group students according to their positive or negative perception of academic context AC and c to analyze the effects of AC on workload.

Using cluster analysis, participants were classified into two groups positive versus negative context. The differences between groups show that a positive AC improves performance p student autonomy and result satisfaction were relevant dimensions of the AC p A participatory ergonomics approach to reduce mental and physical workload.

A step-by-step approach to better work, aimed at reducing mental and physical workload in office work, is evaluated. This approach is based on a strong commitment of the management in the enterprise, and on as much direct worker participation as possible.

After every step the workers proposed how to. Effects of mental demands during dispensing on perceived medication safety and employee well-being: a study of workload in pediatric hospital pharmacies. Pharmacy workload is a modifiable work system factor believed to affect both medication safety outcomes and employee outcomes, such as job satisfaction. This study sought to measure the effect of workload on safety and employee outcomes in 2 pediatric hospitals and to do so using a novel approach to pharmacy workload measurement.

Rather than measuring prescription volume or other similar indicators, this study measured the type and intensity of mental demands experienced during the medication dispensing tasks. The effects of external interruptions, divided attention, and rushing and internal concentration and effort task demands on perceived medication error likelihood, adverse drug event likelihood, job dissatisfaction, and burnout were statistically estimated using multiple linear and logistic regression.

Pharmacists and pharmacy technicians reported high levels of external and internal mental demands during dispensing. The study supported the hypothesis that external demands interruptions, divided attention, and rushing negatively impacted medication safety and employee well-being outcomes. However, as hypothesized, increasing levels of internal demands concentration and effort were not associated with greater perceived likelihood of error, adverse drug events, or burnout and even had a positive effect on job satisfaction.

Replicating a prior study in nursing, this study shows that new conceptualizations and measures of workload can generate important new findings about both detrimental and beneficial effects of workload on patient safety and employee well-being. This study discusses what those findings imply for policy, management, and design concerning automation, cognition, and staffing. Effects of mental demands during dispensing on perceived medication safety and employee well being: A study of workload in pediatric hospital pharmacies.

Holden, Richard J. Background Pharmacy workload is a modifiable work system factor believed to affect both medication safety outcomes and employee outcomes such as job satisfaction. Objectives This study sought to measure the effect of workload on safety and employee outcomes in two pediatric hospitals and to do so using a novel approach to pharmacy workload measurement. Methods Rather than measuring prescription volume or other similar indicators, this study measured the type and intensity of mental demands experienced during the medication dispensing tasks.

The effects of external interruptions, divided attention, rushing and internal concentration, effort task demands on perceived medication error likelihood, adverse drug event likelihood, job dissatisfaction, and burnout were statistically estimated using multiple linear and logistic regression.

Results Pharmacists and pharmacy technicians reported high levels of external and internal mental demands during dispensing. The study supported the hypothesis that external demands interruptions, divided attention, rushing negatively impacted medication safety and employee well being outcomes. However, as hypothesized, increasing levels of internal demands concentration and effort were not associated with greater perceived likelihood of error, adverse drug events, or burnout, and even had a positive effect on job satisfaction.

Conclusion Replicating a prior study in nursing, this study shows that new conceptualizations and measures of workload can generate important new findings about both detrimental and beneficial effects of workload on patient safety and employee well being.

Two great changes in developed countries are taking place: populations are ageing and becoming increasingly overweight.

Combination of these factors with shift work is a risk factor for work ability and mental workload that are dynamic processes which change greatly throughout an individual's work life. The aim of this study was to investigate mental workload and work ability in textile workers and to identify factors which affect work ability and mental workload.

Workload assessment for mental arithmetic tasks using the task-evoked pupillary response. Full Text Available Pupillometry is a promising method for assessing mental workload and could be helpful in the optimization of systems that involve human—computer interaction. The present study focuses on replicating the studies by Ahern and Klingner , which found that for three levels of difficulty of mental multiplications, the more difficult multiplications yielded larger dilations of the pupil.

Using a remote eye tracker, our research expands upon these two previous studies by statistically testing for each 1. The MBR, on the other hand, did not differentiate between the difficulty levels.

Moderate to strong correlations were found between the MPDC and the proportion of incorrect responses, indicating that the MPDC was higher for participants with a poorer performance. For practical applications, validity could be improved by combining pupillometry with other physiological techniques.

Personnel's health surveillance at work: effect of age, body mass index, and shift work on mental workload and work ability index. This cross-sectional study was carried out among male workers in textile industry. Employees based on their job group and work conditions have been divided into 6 categories. They completed work ability index and mental workload questionnaires during three work shifts. Body mass index BMI and demographic details were recorded.

All of the participants rated their work ability as moderate with high mental workload. The mean WAI and mental workload in age group were significant.

The mean BMI was There was a statistically significant correlation between work ability index and shift work. Unlike the previous study, a decrease point in WAI started in early age that may be due to life-style work and another psychological factor; on the other hand, NASA-TLX revealed high score in six subscales that can be another reason for low WAI.

Perceptions of mental workload in Dutch university employees of different ages: a focus group study. Background As academic workload seems to be increasing, many studies examined factors that contribute to the mental workload of academics. Age-related differences in work motives and intellectual ability may lead to differences in experienced workload and in the way employees experience work features.

This study aims to obtain a better understanding of age differences in sources of mental workload. These individual reactions to workload may also be driven by differences in tenure. Most positively assessed work characteristics were: interaction with colleagues and students and autonomy. Moreover, despite great efforts on their part, promotion opportunities seem limited.

A more pronounced role for the supervisor seems appreciated by employees of all ages, although the specific interpretation varied between individuals and career stages. Conclusions To preserve good working conditions and quality of work, it seems important to scrutinize the output requirements and tenure-based needs for employee supervision.

In the study, an Augmented Reality procedure guidance support system concept was designed and used as a tool for the measurement of mental workload and Situational awareness of an SRO Senior Reactor Operator. The EOP was chosen as the scenario for testing because it is the one of the critical plant conditions that requires human intervention and it represents one of the more conservative approaches to the test scenarios that are possible.

The system is expected to realize an improvement in the level of Situational Awareness and mental workload which have been demonstrated by previous studies to be directly linked with the system response to an emergency situation in the MCR.

The planning and design of the project adhered to a Systems Engineering approach in order to provide an optimized framework for ensuring the successful implementation of the system design.

Previous study and research into this topic has emphasized the importance of situational awareness in determining the human factor performance issues in the nuclear power plant Control Room operations.

It is expected that future development work in this area will yield an actualized Augmented Reality system that could incorporate MCR team control and possibly be implemented in the system validation of other I and C systems. Full Text Available Prior researchers indicate that mental load is one of the most important contributors to a traffic accident. The driving test consists of 3 road complicity situation urban road, highway, rural road with 26 drivers with average 21 years old in different experience level average 4.

There are 3 cameras placed on the left side, right side and front car to identify the road condition.

According to experiment, it was found that drivers felt that frustration level, business, and mental -demand factors dominate the impact on high-level workload Based on street complexity, it is necessary to improve road conditions that resemble highway road by reducing potential hazard. Full Text Available Introduction. Fatigue and mental workload are directly associated with high-complexity tasks. The laparoscopic Roux-en-Y gastric bypass LRYGB learning curve is considered to be one of the most difficult to complete in laparoscopic surgery.

A single surgeon was enrolled to undertake 70 consecutive LRYGB procedures with two internal surgeons mentoring the first 35 cases. Patients were consecutive and ranked from case 35 to case according to the date of the surgical procedure "case rank". The procedure was recorded for later viewing by two external evaluators.

General data for patients and surgical variables were collected prospectively. The prevalence of implementation of mental health measures in companies and its association with sickness absence.

The main objective was to determine the prevalence of implementation of mental health measures aimed at the prevention of high workload workload measures and the promotion of work engagement engagement measures in companies and sectors. Additionally, its associations with sickness absence was explored. Cross-sectional survey. An internet-based survey among 12, company representatives in the Netherlands. Descriptive analyses were performed to determine the prevalence, and differences between sectors were tested using Chi-squared tests.

ANOVA was performed to examine the association between companies with or without mental health measures and sickness absence rates. The sectors 'health care and welfare' and 'education' reported to have implemented measures most often. Having implemented engagement measures was significantly associated with lower sickness absence 4. Overall, workload measures were more often implemented than engagement measures.

Future research is recommended to determine reasons for implementation as well as causality in the association between mental health measures and sickness absence.

Assessing mental workload and situation awareness in the evaluation of computerized procedures in the main control room. Yang, Chih-Wei, E-mail: yangcw iner. Highlights: Black-Right-Pointing-Pointer This study investigates procedure types' effects on operators' performance. Black-Right-Pointing-Pointer The computer-based procedure is suggested to be implemented in the main control room.

Black-Right-Pointing-Pointer The computer-based procedure brings lowest mental workload. Black-Right-Pointing-Pointer And it also generates fewer error of omission, and the highest situation awareness. Black-Right-Pointing-Pointer The shift supervisor has the highest workload and the lowest situation awareness. While there are many ways to evaluate computerized procedures design, the user's mental workload and situation awareness SA are particularly important considerations in the supervisory control of safety-critical systems.

Users' mental workload and situation awareness may be influenced by human factor issues relating to computerized procedures, e. Some of the positive impacts of CPs on operator performance include the following: tasks can be performed more quickly; overall workload can be reduced; cognitive workload can be minimized; fewer errors may be made in transitioning through or between procedures.

However, various challenges have also been identified with CP systems. These should be addressed in the design and implementation of CPs where they are applicable. For example, narrower 'field of view' provided by CP systems than with paper-based procedures could reduce crew communications and crewmember awareness of the. Based on a human factors experiment in which each participant monitored and controlled multiple simulated.

Measuring workload in collaborative contexts: trait versus state perspectives. In the present study, we explored the state versus trait aspects of measures of task and team workload in a disaster simulation.

There is often a need to assess workload in both individual and collaborative settings. Using this practice, one may overlook the distinction between traits and states. Fifteen dyadic teams 11 inexperienced, 4 experienced completed five sessions of a tsunami disaster simulator. We then examined the workload items by using a between-subjects and within-subjects perspective.

Between-subjects and within-subjects correlations among the items indicated the workload items are more independent within subjects as states than between subjects as traits.

Correlations between the workload items and simulation performance were also different at the trait and state levels. Workload may behave differently at trait between-subjects and state within-subjects levels. Researchers interested in workload measurement as a state should take a within-subjects perspective in their analyses. Full Text Available One goal of advanced information and communication technology is to simplify work. However, there is growing consensus regarding the negative consequences of inappropriate workload on employee's health and the safety of persons.

In order to develop a method for continuous mental workload monitoring, we implemented a task battery consisting of cognitive tasks with diverse levels of complexity and difficulty.

Analysis of the EEG spectra demonstrates an increase of the frontal theta band power and a decrease of the parietal alpha band power, both under increasing task difficulty level. Based on these findings we implemented a new method for monitoring mental workload , the so-called Dual Frequency Head Maps DFHM that are classified by support vectors machines SVMs in three different workload levels.

In consequence, the hopeful but naive mathematical expressions of workload, while they might represent a first-pass approximation, largely fail to capture the subtleties and nuances of experience of people as they grapple with the varying demands of complex tasks. In contrast to mathematical formulations, there are psychophysiological approaches to the assessment of cognitive workload. Between these two forms of measurement methodologies lies the principal form of assessment, primary task performance.

If it were not for the fact that one wishes to predict workload, simply measuring the output efficiency of individuals with respect to the task they are performing would provide, in large part, the required information.

But because one wants to predict when and how individuals might encounter conditions that exceed their capability that more than primary task measures are needed. However, this does not mean that primary task performance cannot be used to reflect more than instantaneous load level. For example, if a soldier had performed a sequence of operations before, primary task measures might indicate periods of stressful operations.

As mentioned above, there is always the question of context. In aviation for example, it is still reasonable to suggest that periods of high workload are most likely around take-off, landing, or emergency conditions. In the same fashion, if a soldier's mission can be evaluated in terms of expected load, primary task measures can still be most useful, especially if training or simulation of the event is possible beforehand.

For actual, on-line measurement of experienced load, primary task performance is a critical source of information to both central battle managers and potentially, to soldiers themselves. Attention and cognitive workload are intimately linked psychological constructs. With the postulation of Kahneman's concept of attentional resources, there came a paradigm shift in the area of attention that changed the perspective on attention from a filter or gate function. Obviously, the latter construct is far more amenable to integration with a workload perspective.

Intrinsic to the original resource formulation was the postulate that attention was a unitary resource of limited capacity. By inference, tasks that were performed concurrently dual-task performance competed for such limited resources. The demands of performing one task were consequently reflected in the performance level of a second, or secondary task. For those who tied workload directly to attention, workload on a main task could be measured as a reflection of performance level on this subsidiary or secondary task.

Today there are a number of objections to this form of assessment procedure. With respect to soldiers' tasks, the first, pragmatic, and most important objection is that the introduction of a secondary, often artificial, task distracts a soldier from primary performance. Given the presence of other measures of workload, this is a needless addition.

With respect to the assessment of cognitive workload of a soldier, the secondary assessment method of workload measurement is not particularly useful. While objective measures of what a soldier is actually doing are helpful to battle managers and perhaps to the soldier , it is important to integrate the affective domain of response.

Since the proposed technologies are to be used under imminent life-threatening situations, a critical component of the context is the subjective reaction of a soldier. As often noted, even weapons are not used by a significant percentage of soldiers in the heat of battle.

If technology is to prove effective, some assessment of a soldier's subjective state is important. There are several well-known methods of subjective workload assessment. Typically, they elicit paper-and-pencil responses for subsequent analysis, although this is not necessary. Like measures of primary performance, subjective responses represent, principally, the momentary reaction of the individual, although some work has been done on retrospective subjective assessment.

The advantage of subjective ratings is their high face validity, which is a nontrivial factor when dealing with professional operators.

Indeed, it may well be the case that individuals do provide retrospective assessments of the difficulty of particular situations, but in a common professional jargon. It might be possible to link formal subjective techniques to such informal observations to provide useful on-line information concerning the subjective state of individual operators.

Indeed, informally this process would already be a part of the. One of the great hopes in mental workload assessment is the development of a nonintrusive technique that taps directly into cognitive function. The ability to provide information on the direct status of cognitive abilities presents a formidable challenge, but one with extensive payoffs if successful. Like other psychophysiological techniques, the general form of inquiry is a search for a relationship between some measurable facet of central nervous system activity and some concomitant behavioral phenomenon.

The more global the behavior specified e. Since cognitive workload is a function of effort associated with a task, there is reason to believe that psychophysiological techniques should at least provide some hope for assessment.

Individuals have searched almost the whole spectrum of reasonable psychophysiological functions--and even several that are not--to find a measure. The most promising general candidates are related to heart function; however, like all such techniques, it is a matter of distilling signal from noise when one is not sure what a signal looks like.

Often those signals are weak, need amplification, and are subject to unfortunate artifacts. For example, evoked potentials have always held particular promise, but they are accompanied by a number of problems see Humphrey and Kramer, In laboratory settings, psychophysiological equipment can be somewhat intimidating in terms of size and configurations, but contemporary progress in biomedical engineering makes the possibility of micro-assessment systems a firm probability.

That these could be easily incorporated into head-mounted displays is a systems question for future design. Should such integration be possible, psychophysiological measures represent a strong candidate for inclusion in a battery of cognitive workload assessment techniques.