Use of the RoboFlag synthetic task environment to investigate workload and stress responses in UAV operation

Determining the validity of the visual field principle for designing control/display arrangements

The Visual Field (VF) principle has been found to apply in many situations, but has not been tested under many possible conditions of operator posture with different display and control locations. In this research we used four display locations, four control locations relative to a seated operator and tested the strength of population stereotype for six different types of controls with linear displays moving either horizontally or vertically and circular displays with a neutral indicator at the 12, 3, 6 and 9 o'clock positions. Apart from several minor differences in operator responses, the VF principle held up well under all these different display/control relationships. By designing the display/control arrangement to have high stereotype strength, the direction of control movement for a given direction of indicator movement can be selected to comply with the VF principle for producing fewest errors in movement direction.

Workload and Performance: Associations, Insensitivities, and Dissociations

OBJECTIVE

The aim of this study was to distill and define those influences under which change in objective performance level and the linked cognitive workload reflections of subjective experience and physiological variation either associate, dissociate, or are insensitive, one to another.

BACKGROUND

Human factors/ergonomics frequently employs users' self-reports of their own conscious experience, as well as their physiological reactivity, to augment the understanding of changing performance capacity. Under some circumstances, these latter workload responses are the only available assessment information to hand. How such perceptions and physiological responses match, fail to match, or are insensitive to the change in primary-task performance can prove critical to operational success. The reasons underlying these associations, dissociations, and insensitivities are central to the success of future effective human-machine interaction.

METHOD

Using extant research on the relations between differing methods of workload assessment, factors influencing their association, dissociation, and insensitivity are identified.

RESULTS

Dissociations and insensitivities occur more frequently than extant explanatory theories imply. Methodological and conceptual reasons for these patterns of incongruity are identified and evaluated.

APPLICATION

We often seek convergence of results in order to provide coherent explanations as bases for future prediction and practical design implementation. Identifying and understanding the causes as to why different reflections of workload diverge can help practitioners toward operational success.

Training Techniques for Visual Search in Complex Task Environments

OBJECTIVE

The goal for this study was to evaluate several visual search training techniques in an unmanned aerial vehicle (UAV) simulated task environment.

BACKGROUND

Operators controlling remote unmanned vehicles often must perform complex visual search tasks (e.g., target search). These tasks may pose substantial demands on the operator due to various environmental factors. Visual search training may reduce errors and mitigate stress, but the most effective form of training has not been determined.

METHODS

Participants were assigned to one of four training conditions: target, cue, visual scanning, or control. After the training, the effectiveness of the training techniques was tested during a 30-minute simulated UAV flight. A secondary task manipulation was included to further simulate the demands of a realistic UAV control and target search task. Subjective stress and fatigue were also assessed.

RESULTS

Target training produced superior target search performances in more hits and fewer false alarms (FAs) when compared to the control condition. The visual scanning and cue trainings were moderately effective. Only target training performance was vulnerable to the secondary task load. The task was stressful, but training did not mitigate stress response.

CONCLUSION

Training participants on the target and the cue appearance as well as active scanning of the visual field is promising for promoting effective target search for this simulated UAV environment.

APPLICATION

These training techniques could be used in preparation for intelligence, surveillance, and reconnaissance (ISR) missions that involve target search, especially where target appearance change is likely.

Impact of three task demand factors on simulated unmanned system intelligence, surveillance, and reconnaissance operations

The present study investigated how three task demand factors influenced performance, subjective workload and stress of novice intelligence, surveillance, and reconnaissance operators within a simulation of an unmanned ground vehicle. Manipulations were task type, dual-tasking and event rate. Participants were required to discriminate human targets within a street scene from a direct video feed (threat detection [TD] task) and detect changes in symbols presented in a map display (change detection [CD] task). Dual-tasking elevated workload and distress, and impaired performance for both tasks. However, with increasing event rate, CD task deteriorated, but TD improved. Thus, standard workload models provide a better guide to evaluating the demands of abstract symbols than to processing realistic human characters. Assessment of stress and workload may be especially important in the design and evaluation of systems in which human character critical signals must be detected in video images. Practitioner Summary: This experiment assessed subjective workload and stress during threat and CD tasks performed alone and in combination. Results indicated an increase in event rate led to significant improvements in performance during TD, but decrements during CD, yet both had associated increases in workload and engagement.

Multidimensional Profiling of Task Stress States for Human Factors: A Brief Review

OBJECTIVE

This article advocates multidimensional assessment of task stress in human factors and reviews the use of the Dundee Stress State Questionnaire (DSSQ) for evaluation of systems and operators.

BACKGROUND

Contemporary stress research has progressed from an exclusive focus on environmental stressors to transactional perspectives on the stress process. Performance impacts of stress reflect the operator's dynamic attempts to understand and cope with task demands. Multidimensional stress assessments are necessary to gauge the different forms of system-operator interaction.

METHOD

This review discusses the theoretical and practical use of the DSSQ in evaluating multidimensional patterns of stress response. It presents psychometric evidence for the multidimensional perspective and illustrative profiles of subjective state response to task stressors and environments. Evidence is also presented on stress state correlations with related variables, including personality, stress process measures, psychophysiological response, and objective task performance.

RESULTS

Evidence supports the validity of the DSSQ as a task stress measure. Studies of various simulated environments show that different tasks elicit different profiles of stress state response. Operator characteristics such as resilience predict individual differences in state response to stressors. Structural equation modeling may be used to understand performance impacts of stress states.

CONCLUSION

Multidimensional assessment affords insight into the stress process in a variety of human factors contexts. Integrating subjective and psychophysiological assessment is a priority for future research.

APPLICATION

Stress state measurement contributes to evaluating system design, countermeasures to stress and fatigue, and performance vulnerabilities. It may also support personnel selection and diagnostic monitoring of operators.