High Levels Of Workload Research Articles

In-Flight and Postflight Assessment of Pilot Workload in Commercial Transport Aircraft Using the Subjective Workload Assessment Technique

A question relevant for Federal Aviation Administration (FAA) certification of pilot workload in new commercial transport aircraft is whether subjective evaluation of workload should be conducted in-flight or postflight. This article examines the effect of probe timing (in-flight or postflight) for subjective assessment of flights containing both low and high levels of workload using the Subjective Workload Assessment Technique. The B-727, FAA Phase 2-certified, 6-dr, motion-base simulator, and air traffic control simulation at the Man-Vehicle System Research Facility at the NASA-Ames Research Center were used. Each pilot flew three different flights: (a) a nominal flight (30 rain); (b) a communication flight in which the pilot was instructed to tune in and talk on the command radio, in addition to normal duties (30 rain); and (c) a malfunction flight, including two diversions and an engine and "A" hydraulic system failures (1 hr 30 min). Sixteen B-727 qualified airline pilots flew the three flights on two separate occasions in a test-retest paradigm. No effect for probe timing (in-flight or postflight) was found for the nominal and communication flights. A significant (Probe Timing x Phase of Flight) interaction was found for the malfunction flight. It appears that postflight ratings of high-workload events receive higher workload ratings than in-flight ratings of the same event.

Job Conditions and Intentions to Quit

Higher quitting rates and concerns with satisfaction and commitment are common in resort industries. A field study at a large mountain resort was conducted to assess the degree to which specific job conditions influenced stress, job satisfaction, organizational commitment, and assessment of occupational alternatives, and how these in turn, influenced intentions to quit. Specifically, it was thought that job demands, supervisory style, pay satisfaction, role conflict, and training issues would influence psychological stress levels, job satisfaction, and organizational commitment which would affect intentions to quit. A questionnaire assessing these constructs was given to 440 full-time employees of a ski resort. Two hundred usable questionnaires were returned. Path analysis was used to assess the model. Results showed that supervisory style, prolonged static work postures, high levels of workload, and role conflict were predictors of psychological stress. Role conflict, psychological stress, and job satisfaction were significant predictors of organizational commitment, and organizational commitment was indeed negatively linked to intent to quit. The strongest predictors of intentions to quit were job satisfaction and organizational commitment. Subsequent analyses attempted to differentiate between levels of organizational commitment and job satisfaction as well as between seasonal and year round employees using additional job condition variables which were not included in the original path analysis. This group of additional variables included the Work Environment Scales, and other job conditions such as repetitiveness, task significance, skill utilization, departmental cooperation, and job security. Staff support, autonomy, job involvement, and task clarity were found to significantly discriminate between low, medium, and high levels of both satisfaction and organizational commitment. Several of the additional job condition variables differentiated between employment type (seasonal vs. year round), thus implying that these other job conditions may influence employee ITQ through the mediating constructs of organizational commitment and job satisfaction.

Electronic Performance Monitoring, Job Design and Psychological Stress

This study helps establish how electronic performance monitoring may influence employee physical strain levels through job design. It identifies job design variables which differ between monitored and non-monitored employees in the telecommunications industry (using discriminant function analysis). These variables' relationships to psychological stress outcomes were examined using multiple regression analysis. A group of 704 employees in three job categories (telephone operator {n=228}, customer service representative {n=230}, and clerk {n=246}) responded to a questionnaire survey mailed to their residence. Four hundred thirty-four of the respondents were monitored and 264 were not. The results indicated that the monitored employees had significantly higher levels of reported psychological stress than the non-monitored employees. The discriminant function analysis of job design variables showed that a variety of job design factors discriminated between monitored and non-monitored employees. High levels of workload, few lulls between periods of high workload, high levels of career/future ambiguity, poor relationships with supervisors, as well as low levels of task meaningfulness and completeness were significant predictors of psychological stress outcomes (tension, anxiety, depression and fatigue).

Assessment of Workload in a Field Environment

This study evaluated the impact on crew workload of adding the STINGRAY weapon system to the Bradley Fighting Vehicle (BFV). Four BFV crews participated in force-on-force offensive and defensive missions in a baseline BFV (without STINGRAY) and a BFV with STINGRAY. Workload was assessed through operator ratings, post-mission debriefs, and video and audio recordings. A signficant relationship between workload and force effectiveness was demonstrated (i.e., higher levels of workload were associated with lower levels of force effectiveness). Results indicate that workload was dependent on mission type (offensive, defensive) and the mode of operation (baseline, STINGRAY-automatic, STINGRAY-semiautomatic, and STINGRAY-manual). Crew strategies to reduce workload included reallocation of some of the Bradley commander (BC) tasks to the gunner. The utility of the workload techniques employed in the study is discussed.

Effects of Noise and Workload on Performance with Two Object Displays vs. a Separated Display

This study examines the effects of stress on the processing of displayed information from two types of object displays, when dimensions were formed by the color and size of a bar, by the height and width of a rectangle, and from a separated two bargraph display. Subjects either integrated information across the two dimensions of each display or focused attention on each dimension, in a simulated airborne decision task. In Experiment 1 (14 subjects), stress was imposed via three levels of workload of a concurrent visual search task. In Experiment 2 (14 subjects), it was imposed by 88 dB helicopter noise. Results indicated that information integration was best supported by the rectangle display at higher levels of workload. Both the color bar and the bargraph display were associated with poor performance on the integration task, but were superior on the focused attention task. Hence, an emergent feature of the rectangle (its area), rather than objectness per se, was the critical element supporting information integration and disrupting focused attention. The imposition of noise enhanced the subjective feeling of stress. Noise did not influence performance on the decision task, but differentially affected the resources necessary to extract that information. Noise reduced the resource demands of both object displays and increased the resource demands of the separate bargraph display.

The impact of job demands and behavioral control on experienced job stress

AbstractThe present study examines the impact of behavioral control on the experience of work strain under conditions of work overload. Extending experimental laboratory findings that suggest that control can lessen the impact of aversive stimuli on psychological and physiological strain responses, we hypothesized an interaction between control and workload such that the effects of high demands on strain would be less if the worker had behavioral control over the task. This hypothesis is also consistent with Karasek's job demands‐job decision latitude model of work strain and health. The hypothesis was tested in a laboratory experiment in which 125 subjects worked on a mail sorting task with either a high or moderate level of workload and either a high or low level of behavioral control. Strain responses were assessed with measures of job satisfaction, anxiety, and physiological arousal. The hypothesis was only partially supported in that high control lessened the impact that work overload had on anxiety. While not fully supportive of the model, the results are seen as conservative given the constraints on the manipulation of work overload inherent in the laboratory environment.

An Investigation of the “Von Restorff” Phenomenon in Post-Test Workload Ratings

The present experiment was designed to examine the possibility of a “von Restorff” effect occurring during post-task ratings of difficulty, effort and workload as a result of performing tasks containing an isolated period of high workload. The task employed was a hovercraft simulation which combined elements of skill-based tracking and rule- and knowledge-based process control. The performance of five separate tasks was compared. In the first, subjects performed missions which presented a relatively low level of workload from throughout while the second presented a high level of workload from throughout. The final three conditions were designed to produce isolated peaks in workload which occurred either early, midway or late in the mission. Results demonstrated that ratings on the three scales increased steadily as the peak approached the end of the mission. Further, the ratings for the early increase were only slightly greater than those reported for the task containing a low level of workload throughout. An analysis of error rates demonstrated that there was evidence for the dissociation of performance and workload which was especially apparent when the increase occurred at the beginning of the mission.

Evaluation of a Pilot Workload Metric for Simulated VTOL Landing Tasks

A methodological approach to measuring workload was investigated for evaluation of new concepts in VTOL aircraft displays. Multivariate discriminant functions were formed from conventional flight performance and/or visual response variables to maximize detection of experimental differences. The flight performance variable discriminant showed maximum differentiation between crosswind conditions. The visual response measure discriminant maximized differences between fixed vs. motion base conditions and experimental displays. Physiological variables were used to attempt to predict the discriminant function values for each subject/condition/trial. The weights of the physiological variables in these equations showed agreement with previous studies. High muscle tension, light but irregular breathing patterns, and higher heart rate with low amplitude all produced higher scores on this scale and thus, represented higher workload levels.

Comparison of Five Mental Workload Assessment Procedures in a Moving-Base Driving Simulator

Five methods of measuring mental workload (secondary task performance, visual occlusion, cardiac arrhythmia, subjective opinion rating scales, and primary task performance) were compared for sensitivity to changes in operator loading. Each was used to differentiate among low, medium, and high levels of workload defined in terms of the application point of crosswind gusts in a driving task. The driving task was produced using an automobile driving simulator with a six-degree of freedom computer generated display, a four-degree of freedom physical motion system, and a four-channel sound system. Techniques of mental workload measurement that have shown promise in previous studies were used as a between-subjects factor, and subjects were presented with a within-subject factor of wind gust placement. Gusts at the front of the vehicle represented high workload levels, and gusts toward the center of the vehicle represented progressively lower levels of workload. The results showed significant differences among workload levels for subjective opinion scales and primary performance measures of lateral deviation, yaw deviation, and steering reversals. A relative sensitivity estimate of these would be, from highest to lowest sensitivity, steering reversals and yaw deviation, rating scales, and lateral deviation. The techniques of occlusion, cardiac arrhythmia, and secondary task performance yielded no significant workload effect.

Comparison of Primary and Secondary Task Measures as a Function of Simulated Vehicle Dynamics and Driving Conditions

In a previously reported experiment involving a moving base driving simulator with computer-generated display, secondary task measures of workload showed significant increases as a function of large changes in vehicle dynamics and disturbance levels. Because the secondary task measures appeared less sensitive than desired, driving performance measures recorded during the same experiment were later analyzed. Particular emphasis in examining the driving performance data was placed on (1) determining the degree of intrusion of the secondary task on the driving task as a function of the independent variables, and (2) on comparing the sensitivity of the primary and secondary task measures. The results showed the secondary task does intrude significantly upon the driving task performance at low workload levels, but that it does not significantly intrude at high workload levels. Also, when the four primary task measures were analyzed for sensitivity to the independent variables, new information was obtained indicating greater sensitivity than is obtained with the single secondary task measure. Steering ratio, for example, is found to affect performance at high disturbance levels—a result not obtained in examining the secondary task by itself. The merits of primary and secondary task performance analysis are discussed, and suggestions are made for future work.

Results of aortocoronary artery saphenous vein bypass surgery for ischemic heart disease

The results of direct myocardial revascularization using aortocoronary artery saphenous vein bypass grafting in 100 consecutive patients with ischemic heart disease are evaluated. Twelve patients died at operation or early thereafter. Of 88 patients surviving, 72 had severe angina pectoris before operation, 15 had moderate angina and 1 mild angina. After operation, only 10 patients had severe angina, 6 had moderate angina and 72 were free of angina. Thirty-seven patients underwent an exercise stress test in the upright position using a bicycle ergometer 3 to 5 days before operation. Angina pectoris developed in 33 patients during exercise and was accompanied by significant S-T segment depression. The exercise study was terminated in four patients who experienced shortness of breath. Three to four months postoperatively, 20 of these 37 patients underwent exercise at similar and higher work load levels. No pain or S-T segment depression was noted in 18 of the 20 patients. Two of the 20 patients had positive exercise responses similar to their preoperative responses. Seventeen of the 37 patients did not undergo exercise testing after operation: Four died; eight showed clinical improvement but were not available for repeat exercise studies; the remaining five showed no clinical improvement and did not undergo repeat exercise studies. Left ventricular function was determined by measuring ejection fraction and mean velocity of circumferential fiber shortening per circumference in 51 patients. The preoperative ejection fraction of patients who manifested clinical improvement after operation was greater than that of patients whose condition did not improve; how-ever, there was considerable overlap of data. The success or failure to achieve a good clinical result correlated with flow through the bypass, measured at the time of operation. Flow through the saphenous bypass was directly related to the state of the distal coronary arterial system.