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PubMed1997

Factors influencing mental workload indexes.

Several findings of the author's own mental workload research are reviewed. Especially, factors, except task demand, influencing mental workload indexes are discussed. First, an experiment using the National Aeronautics and Space Administration Task Load Index (NASA TLX) is reviewed and the effects of a prior task load on a subsequent subjective workload are described. In a physiological measures section, the low reliability of the heart rate variability (HRV) parameters when the subjects' respiration pattern are highly irregular, and the existence of low sweat respondent, although perspiration seems to be sensitive to the workload, are indicated. Furthermore, results of the task specific physiological responses and of a HRV parameter affected by the individual characteristics, like type A behavior pattern, are shown. Discrepancy between autonomic nervous system activity measures may be solvable by introducing a new concept of autonomic space (synergism of sympathetic and parasympathetic nervous system). Finally, the need for strategies of data management concerning the individual differences is emphasized.

Autonomic Nervous System↗

PubMed1997

[Multivariate discriminant analysis for assessing mental workload during duel task operation].

In order to investigate the efficiency of multivariate discriminant analysis in the assessment of mental workload during dual task operations, various psychophysiological indices and performance were recorded. The dual task consisted of the primary visual tracking task and the secondary Oddball task. The results indicated that tracking error, latency of P3 and IBI of HR correlated well with the mental workload and the multivariate discriminant analysis succeeded in classifying the levels of mental workload with higher conformation rate than those using the single index. It suggests that multivariate discriminant analysis is meaningful in the assessment of mental workload under dual task situations.

Aerospace Medicine↗

PubMed1998

Occupational workload of fisherwomen in India.

A group of 60 fisherwomen, aged 20 to 50 yrs., were studied to evaluate their occupational workloads. Of the eight activities involved in fish handling, only four, viz., sorting, washing, drying, and selling, which are most frequently carried out by the fisherwomen, were selected. The heart rate responses and rating of perceived exertion (RPE) were used as measures of occupational workload. Based on the findings, the occupational workload could be classified as "moderately heavy". A significant influence of age and body weight on the physiological workload was observed, being negatively correlated with age and positively with weight.

Adult↗

PubMed1998

Frequency of patients' consulting in general practice and workload generated by frequent attenders: comparisons between practices.

BACKGROUND: Patients who attend frequently may present a problem for general practitioners (GPs) in several ways. The frequency of patients' consulting, comparisons between practices, and the effect of frequent consulting on the clinical workload have not been quantified previously. AIMS: To examine the distribution of the number of consultations per patient in four general practices. To estimate the clinical workload generated by frequent attenders. To model the data to demonstrate the contribution of age, sex, and practice on the likelihood of attending frequently. METHOD: Analysis and modelling of a validated data set of date records of consultations collected routinely over a 41-month period from four practices in and around Leeds, representing 44,146 patients and 470,712 consultations. RESULTS: A minority of patients consulted with extreme frequency. All practices had similar distributions but varied with respect to the numbers of frequent attenders, and the frequencies of their consulting. The most frequent 1% of attenders accounted for 6% of all consultations, and the most frequent 3% for 15% of all consultations. Females and older people were more likely to be frequent attenders. CONCLUSION: Frequent attenders have an important effect on GPs clinical workload. Between one in six and one in seven consultations are with the top 3% of attenders. Further research is needed to explain the behaviour underpinning frequent attendance in order to identify appropriate management strategies; such strategies could have an important effect on clinical workload.

Adolescent↗

PubMed1986

Hormonal responses to a graded mental workload.

Three mental arithmetic tests of graded difficulty were presented to eight young male volunteers on consecutive days. The effort compensation patterns were investigated using urinary catecholamines and salivary cortisol. A significant increase in adrenaline excretion was found in response to all three tests. Urinary adrenaline was partially graded according to the level of difficulty of the tests. The response patterns to mental workload also included a significantly lower noradrenaline/adrenaline ratio and a higher adrenaline/dopamine ratio after the tests. No significant increase was found after the tests for noradrenaline and dopamine. Changes in salivary cortisol concentration during the tests were graded with respect to test difficulty between the easiest and both of the more difficult tests. Salivary cortisol concentration changes are proposed as the basis for field observations involving mental workload. It is concluded that mental workload causes distinguishable effort compensation patterns and that under certain conditions urinary adrenaline and salivary cortisol allow one to distinguish different mental workload levels.

Adult↗

PubMed1990

Driver workload during differing driving maneuvers.

Motorcycle-automobile accidents occur predominantly when the car driver turns left across the motorcyclist's right-of-way. Efforts to decrease this specific collision configuration, through an increase in motorcycle conspicuity, have concentrated on the physical characteristics of the motorcycle and its rider. The work reported here examines the behavior of car drivers during different driving sequences, in particular during left-turn maneuvers. An experiment is reported that used simultaneous video-taping of the driver and the forward-looking scene. Subjects followed a preset on-road course and were observed for head movements to determine the possibility of structural interference eye-blink frequency, probe-response time, and probe response error, as measures of cognitive or mental workload. In addition, the subjects completed two major subjective workload evaluations as reflections of effort directed to different components of the driving task. Results indicated that there were significant increases in head movements and mental workload during turn sequences compared to straight driving. This result of higher driver workload may be responsible for increasing the potential for detection failure. Such a propensity is also fostered by the higher structural interference that may be expected during turns. Failures to observe during turning sequences have differing outcomes depending on the presence of opposing traffic, as during the left turn, compared with the absence of such opposition, as occurs in the right turn. Also, the less conspicuous the oncoming vehicle in the left turn scenario, the higher the probability of detection failure. At the present time the least conspicuous powered vehicle is the motorcycle.

Accidents, Traffic↗

PubMed1990

Eye movement indices of mental workload.

Four investigations were carried out to assess the feasibility of using eye movement measures as indices of mental workload. In the first experiment, saccadic extent was measured during free viewing while subjects performed low, moderate and high complexity, auditory tone counting as the workload tasks. The range of saccadic extent decreased significantly as tone counting complexity (workload) was increased. In the second experiment the range of spontaneous saccades was measured under three levels of counting complexity with a visual task that did not require fixation or tracking. The results indicated that the extent of saccadic eye movements was significantly restricted as counting complexity increased. In the third experiment, the effects of practice were examined and decreased saccadic range under high tone counting complexity was observed even when significant increases in performance occurred with practice. Finally, in experiment 4, the first experiment was repeated with additional optokinetic stimulation and the saccadic range was again observed to decrease with tone counting complexity. The results indicated that the extent of spontaneous and elicited eye movements was significantly restricted as counting complexity increased. We conclude that this measure may provide a valuable index of mental workload.

Adult↗

PubMedDate not supplied

Intracerebral event-related potentials during memory workload.

The goals of this research were to use an original Memory Workload Paradigm with visually presented words and to explore the following points: (1) With depth electrodes, stereotaxically implanted in intracerebral structures bilaterally (amygdala, anterior hippocampus, posterior hippocampus, orbital-frontal, anterior cingulate gyrus and cortical areas) to delineate brain structures involved in this memory workload task. (2) To investigate whether a memory load effect can be demonstrated on the latencies and amplitudes of the late components of intracerebral event-related potentials (ERPs). (3) If a load effect is present, do intracerebral ERP latencies and amplitudes vary as a function of memory set size? The analysis of intracerebral ERPs revealed that a negative waveform with a maximum amplitude around 400 ms was the component which was significantly involved in memory workload tasks. Significant load effects for the N4 latency were found in both amygdalae and the left posterior hippocampus, as well as both anterior regions of the second temporal gyri (p < 0.01). The intracerebral N4 latency varied linearly as a function of set size while the amplitude varied quadratically for the right amygdala and the left posterior hippocampus (p < 0.05). The results support the conclusion that the Memory Workload Paradigm provides the possibility to use memory load effect on ERPs as a marker to identify which intracerebral structures are predominantly involved in memory functions.

Adult↗

PubMed1991

Workload and job satisfaction among general practitioners: a review of the literature.

The workload of general practitioners (GPs) is an important issue in health care systems with capitation payment for GPs services. This article reviews the literature on determinants and consequences of workload and job satisfaction of GPs. Determinants of workload are located on the demand side (list size and composition of the patient population) and the supply side (organization of the practice and personal characteristics of the GP). The effects of workload and job satisfaction on workstyle and quality of work have been reviewed. The length of consultations or booking intervals seems to be an important restriction for workstyle and quality of work.

Job Satisfaction↗

PubMed1995

Effects of attention and time-pressure on P300 subcomponents and implications for mental workload research.

Our approach to objective measures of mental workload is establishing relationships between components of the event-related brain potential (ERP) and information processing stages. These relationships can be used to infer the influence of specific workload conditions on specific processing stages. We recently showed that the ERP component P300 in choice tasks is composed of two subcomponents, P-SR and P-CR, which are time-related to stimulus-evaluation and response-selection. With these relations we could specify which processing stages were affected when certain workload conditions are varied. When attention was divided between the visual and auditory modalities compared to (unimodal) focused attention, the choice reaction time (RT) was prolonged, primarily in the auditory modality. This delay was mainly reflected in the P-CR latency, which shows that the division of attention mainly impairs the response-selection process in the auditory modality due to a bias of attention towards the visual modality. When the time-pressure was increased, the latency of the P-CR (and not of the P-SR) was shortened, but less than the choice RT. This suggests a (limited) acceleration of response-selection but not of stimulus evaluation. Since the response-selection process was accelerated less than the overt choice RT, an increase of the error rate was consequently observed. In summary we showed that increases of mental workload can induce accelerations or decelerations of specific processing stages which can be monitored by observing latency changes of the affiliated ERP components.

Adult↗

PubMed2000

On-line driver workload estimation. Effects of road situation and age on secondary task measures.

In order to develop a driver-car interface that adapts the presentation of messages generated by in-vehicle information systems to driver workload, two experiments investigated potential determinants of driver visual and mental workload as indicated by performance on two secondary tasks. Experiment 1 suggested that road situation is a major determinant of visual and mental workload of the driver and that the processing resources of older drivers are somewhat more limited than those of younger and middle-aged drivers. Familiarity with the area of driving (when guided) and time of day (associated with traffic density) showed no secondary task effects. Experiment 2 showed that the categorization of road situations, proposed in Experiment 1, could underlie adaptation of visually loading messages to the workload incurred by driving. This was not found with respect to mentally loading messages.

Adult↗

PubMed1990

Maximum acceptable repetitive lifting workload by Chinese subjects.

This study used psychophysical methods to determine the acceptable mean maximum lifting workload for eight Chinese young male subjects, and examined the effects of lifting technique (including freestyle, stoop and squat), lifting frequency (including 2, 3, 4, 5 and 6 lifts/min) and physical characteristics on the maximum acceptable workload. The results are described as follows: (1) The maximum acceptable weights selected by subjects varied from 11.34 to 18.33 kg with changes in lifting technique and frequency. These data were lower than those previously obtained; (2) The upper limit of physiological tolerance over an 8 h workday was also generally lower than previously suggested. However, this upper limit varied with changes in lifting technique and frequency, and in some circumstances it was the same as or even higher than previous limit; (3) Lifting efficiency was affected significantly by technique and frequency. The rank order of efficiency for three lifting techniques were freestyle, stoop and squat. Efficiency was greatest when lifting frequency was between 5 and 6 lifts/min; and (4) The correlations between the maximum acceptable workloads selected by subjects and anthropometric sizes were significant, but those between maximum acceptable workload and isometric strength were not.

Adult↗

PubMed1999

The influence of aircraft proximity data on the subjective mental workload of controllers in the air traffic control task.

This paper outlines an investigation of the impact of aircraft proximity and relationship data on the subjective mental workload of air traffic controllers. Aircraft relationships were categorized into one of 81 different categories, and these relationships were then used to predict subjective mental workload values (as reported by the participants). The results indicated that this methodology could predict subjective mental workload to an accuracy of 73%, with post-hoc analysis improving this prediction rate to 93%. These results are discussed with respect to their contribution to an understanding of the drivers of mental workload in Air Traffic Control.

Adult↗

PubMed1989

Workload, stress, and strain among police officers.

Data relevant to stress and strain were analyzed separately for police officers with high and low workloads. Although these groups of officers were not found to differ in demographic characteristics or on overall levels of stress and strain, the sources of stress and strain were remarkably different. For the low workload officer, the sources of stress and strain appear to be difficulties in interpersonal relations with peers, community, and especially with supervisors. These difficulties appear to be mediated by effects on self-evaluation. The sources of stress and strain among high workload officers appear to be stress-producing events in their lives in general, as well as in performing the job of patrol officer and in dealing with crime and related matters. The differences between high and low workload officers can be explained by social comparison theory, by identity theory, or by Selye's stress theory.

Achievement↗

PubMed1980

Workload recording by microcomputer.

Workload recording as designed by the College of American Pathologists has proven to be an invaluable aid in the assessment of overall laboratory operation. The administrative information derived from the compilation of these workload statistics is utilized to provide effective and these workload statistics is utilized to provide effective and efficient laboratory management. A microcomputer-based system for the pathology department that permits the accumulation of daily raw workoad data is descirbed. A monthly cummulative summary report is subsequently produced, complete with computer-derived College of American Pathologists workload units.

Computers↗

PubMed1995

Relationship between heart rate and oxygen kinetics during constant workload exercise.

BACKGROUND: Oxygen uptake during constant workload exercise increases exponentially from its resting value before reaching a steady state. The difference between the actual rate of oxygen consumption at the onset of exercise and the steady state is an oxygen deficit. Similarly, the normal sinus node increases its rate at the onset of exercise before achieving a steady state, thereby producing a heart rate deficit. The purpose of this study was to test the hypothesis that elimination of the heart rate deficit by an instantaneous increase in heart rate at the onset of constant workload exercise to the steady-state level would reduce the oxygen deficit and improve the perceived difficulty of exertion as compared with the chronotropic response of the normal sinus node. METHODS AND RESULTS: Ten subjects with normal sinus node function who had DDD pacemakers implanted for AV block completed a symptom-limited maximal treadmill exercise test using the Chronotropic Assessment Exercise Protocol (CAEP) to assess sinus node function, maximal heart rate, and VO2max. The subjects then performed constant workload exercise tests (6-min duration) at a workload equal to approximately 50% of metabolic reserve with the pacemaker randomly programmed to each of three patterns of chronotropic response: (1) DDD (lower rate 60 beats/min); (2) Fast (lower rate abruptly programmed to the expected value at 50% metabolic reserve); and (3) Overpaced (lower rate at least 80% of the age predicted maximum). The oxygen deficit was lower with the fast chronotropic response (434 +/- 238 mL O2) than with either the DDD (512 +/- 233; P = 0.02), or overpaced chronotropic patterns (488 +/- 238; P = 0.02 vs fast). The rate constant for change in VO2 was highest with the fast chronotropic pattern (2.85 +/- 1.38) compared with either the DDD (2.25 +/- 0.64; P = 0.01) or overpaced (2.38 +/- 0.43; P = 0.02) patterns. The Borg perceived exertion rating was lowest with the fast chronotropic response (P = 0.02 vs DDD and P = 0.02 vs overpaced). CONCLUSIONS: The results of this study suggest that oxygen kinetics and exertional symptoms are improved by an abrupt increase in pacing rate at the onset of exercise to a value that is appropriate for metabolic demand as compared with the DDD pacing mode in patients with normal sinus node function. In contrast, an overly aggressive chronotropic response was not associated with improved oxygen kinetics or exertional symptoms.

Adult↗

PubMed1990

Out of hours workload of a suburban general practice: deprivation or expectation.

The out of hours workload of a training practice in a suburban and semirural area on the south coast of England was studied for one year. An overall rate of contact of 273/1000 patients was found, which indicated a workload greater than that reported in most other studies. The duty doctor received over 35 telephone calls from patients during some Saturdays (1200 Saturday to 0800 Sunday) and Sundays (0800 to 0800 Monday), up to five being between 2300 and 0700. Of the patients who contacted a general practitioner, 44% were given advice by telephone and 4.9% were admitted to hospital. The admission rate was lower than that given in other studies. A considerable proportion of the workload arose from doctors covering the casualty department of a cottage hospital. Patients having a high expectation of 24 hour care by general practitioners in an area of comparative affluence (Jarman indices -13.8 to 1.7) may account for this aspect of the workload.

England↗

PubMed1985

A study of workload units in five microbiology laboratories.

A study of a modified Canadian unit system of measuring laboratory workload was undertaken in five joint Public Health Laboratory Service and hospital microbiology laboratories. Ten percent of the specimens received over six months were sampled, the number of units expended on each was recorded, and the results were analysed on a central computer. The process of gathering information in the absence of laboratory computers was time consuming and, despite careful planning, differences were found in the recording practices of the laboratories. The analysis of results did not lead to major changes in data gathering techniques because the same information about laboratory workload could be obtained by collecting numbers of clearly defined specimens. Analysis of workload units could be useful for particular purposes, such as comparing differences between laboratories using different techniques for the same investigation or assessing the possible benefits of automation. It must be appreciated, however, that workload units are measures of quantity not of laboratory performance.

Blood↗