Predicting Cognitive Vigilance Performance from Cerebral Blood Flow Velocity and Task Engagement

Responses to a brief six-min screening battery involving high-workload tracking, verbal working memory, and line discrimination tasks were used to predict subsequent performance on a 36-min cognitive vigilance task. Two predictors of interest were subjective state, as indexed by the Dundee Stress State Questionnaire (DSSQ), and cerebral blood flow velocity (CBFV), measured via transcranial Doppler ultrasonography. The results testify to the importance of assessing task-induced responses for predicting cognitive vigilance performance. They also indicate that forecasting vigilance performance is a complex endeavor requiring a set of multidimensional predictors. Specifically, higher post-battery task engagement scores on the DSSQ in this study and higher levels of CBFV during performance of the screening battery predicted more correct detections on the subsequent vigilance task. These findings are interpreted in the light of the resource-workload model of vigilance, and their practical significance is discussed.

Individual Differences in Fatigue and Stress States in Two Field Studies of Driving

Two studies of real-life driving are reported in which individual differences in fatigue and stress were explored in Australian professional and non-professional drivers. In Study 1 58 truck drivers completed subjective measures of mood and stress states before and after a prolonged driving trip. The Task-Induced Fatigue Scale (TIFS) was also used to assess fatigue before and after driving. The Driver Stress Inventory Fatigue Proneness Scale was completed before the driving trip to assess individual differences in fatigue. In Study 2 104 non-professional drivers completed the same subjective state measures before and after a short-duration drive, as drivers in Study 1. Drivers also completed the Fatigue Proneness Scale. Fatigue-prone drivers in both studies showed elevated levels of state fatigue, tension, unpleasant mood and task-related cognitive interference. The results suggest that high Fatigue Proneness drivers may be at risk from fatigue during both prolonged and relatively short driving trips.

The Common Cold Impairs Visual Attention, Psychomotor Performance and Task Engagement

A study was conducted to test the effects of naturally-occurring colds on visual attention, psychomotor performance and subjective indices of stress. 204 participants performed a battery of tasks assessing simple reaction time, focused attention, categoric search and vigilance, on two separate occasions. Affective, motivational and cognitive stress state dimensions were measured using a validated questionnaire. On the first occasion, all participants were healthy. On the second occasion, approximately half the sample suffered from a cold. Comparison of cold sufferers with healthy controls showed significant cold effects. In the cold group, response was slower on simple reaction time and focused attention tasks, and detection rate on the vigilance task was lower. Colds reduced subjective task engagement (e.g., lower energy and motivation) and increased distress (e.g., more negative mood). Regression analysis indicated a direct effect of colds on simple reaction time, whereas the cold effect on vigilance appeared to be statistically mediated by reduced task engagement. It is concluded that colds can produce operationally-significant performance deficits on a variety of attentional tasks.

Assessment of Motivational States in Performance Environments

The development of a new measure of operator motivational state is described, within the framework of a model of subjective stress that distinguishes Task Engagement, Distress and Worry as fundamental aspects of state (Matthews et al., 1999). Previous work on task motivation suggests that strivings for success should be distinguished from interest in the task. Factor analysis of items representing these constructs in a sample of 880 supported the development of reliable, psychometrically distinct scales for Success and Interest Motivation. Both dimensions relate to Task Engagement, but Success Motivation, perhaps surprisingly, is also associated with negative emotions and self-beliefs. The two scales showed different patterns of dependence on task factors. They were also distinguished by differing associations with workload and coping measures, although both related to higher effort and use of task-focused coping. It is concluded that the scales are promising for use in human factors research that addresses the need to structure tasks for greater operator interest and engagement.

Further Tests of an Abbreviated Vigilance Task: Effects of Signal Salience and Jet Aircraft Noise on Performance and Stress

The effects of signal salience and jet-aircraft noise on performance and self-reports of stress were examined in an abbreviated vigilance task (12 min) that duplicates many of the findings with longer duration vigilance tasks (Temple et al., 2000). As is the case with longer vigils, signal detection in the abbreviated task was poorer for low salience than for high salience signals and stress scores, as indexed by the Dundee Stress State Questionnaire (Matthews, Joiner, Gilliland, Campbell, & Falconer, 1999), were generally greater when observers were required to detect low as compared to high salience signals. Unlike longer vigils, however, signal detection in the abbreviated task was superior in the presence of noise than in quiet, and noise generally attenuated self-reports of stress. The beneficial effect of jet-aircraft noise for the abbreviated task differentiates it from longer vigilance tasks and suggests that noise may have short-term positive value in vigilance.

Personality, Coping and Task-Induced Stress in Customer Service Personnel

This study investigated predictors of stress responses in customer service personnel working for a major telecommunications company. 91 participants performed a simulation of their work task. They were presented with telephone inquiries, and tested for their knowledge of the correct response. Several findings of a previous study (Matthews & Falconer, 2000) were replicated. Performing the task appeared to be intrinsically stressful, as evidenced by a large magnitude increase in subjective distress. Individual differences in stress state were related to strategy for coping with task demands. The ‘Big Five’ personality traits were compared with measures of dispositional coping style as predictors of subjective stress state. Coping measures added significantly to the variance in stress state explained by the Big Five. Emotion-focused strategies such as self-criticism appeared to be especially damaging in the customer service context. Coping measures might be used by organizations to select operators likely to be resistant to task-induced stress.

Perceived Mental Workload in an Endocopic Surgery Simulator

Endoscopic surgery–a procedure wherein a target organ is displayed on a monitor and physicians use graspers to manipulate the tissue - has benefits for patients in terms of reduced blood loss, infection, and pain. However, physicians' informal reports indicate that this type of surgery is challenging to perform. These challenges arise from the need to view the target tissue on a monitor, resulting in reduced depth information as well as a disruption of the normal hand-eye mapping. This study represents the initial experimental effort to assess the workload demands experienced in an endoscopic surgery simulator using the NASA-Task Load Index (TLX), a well validated workload measure, and the Multiple Resource Questionnaire (MRQ), a newly developed workload scale. The TLX revealed that the workload experienced in the simulator was indeed high. Additionally, the MRQ revealed different workload profiles associated with different levels of handeye mapping disruption.

Age and Gender Differences in Stress Responses during Simulated Driving

A study of group differences in susceptibility to stress during simulated driving is reported. 74 drivers participated, with approximately equal numbers of younger (18-25) and older (55-78) drivers, and of men and women. Stress was manipulated by exposing half the sample to a failure experience; frequent, uncontrollable skids. Following the stress manipulation, drivers' hazard perception, speed and vehicle control were assessed. Subjective state before and after the drive was assessed by questionnaire. It was hypothesized that older and female drivers might show greater subjective distress and performance impairment in the stress condition. Results showed that age was a stronger influence on performance than either gender or stress. Older drivers showed impairments in hazard detection and vehicle control, but appeared to compensate through slower speed. Older drivers and women showed higher levels of distress throughout the study, but these groups did not show any differential sensitivity to the stress manipulation. It is concluded that driver stress as a safety problem largely depends on individual differences, although group differences may be evident in other circumstances.

Sustained Visual Attention during Simultaneous and Successive Vigilance Tasks

A study of sustained visual attention during simultaneous and successive vigilance task paradigms is reported. 50 participants completed a simultaneous sensory vigilance task with a low event rate, and 50 different participants completed a successive sensory vigilance task with a low event rate. In the simultaneous task participants were presented with pairs of digit-like stimuli on a PC monitor display, and were asked to detect when one of the stimuli was slightly smaller than the other stimulus. In the successive task version participants were required to compare the size of the currently viewed digit pair with the previously presented stimuli, requiring use of memory to detect the target. All participants completed a variety of subjective measures of stress states before and after the vigilance task. The results indicated that the vigilance decrement was greater for sensory simultaneous than for sensory successive tasks. Practical implications of the study are discussed.

Challenges to the Mindlessness Model of Vigilance through Signal Regularity

Robertson et al. (1997) have proposed that detection failures in vigilance tasks result from a “mindless” withdrawal of attentional effort from the monitoring assignment. To explore that view, they modified the traditional vigilance task in which observers make button-press responses to signify the detection of rarely occurring critical signals to one in which button-press responses acknowledge frequently occurring non-signal events and response-withholding signifies signal detection. This modification is designed to promote a mindless withdrawal of attentional effort from the task through routinization. The present study challenges the validity of the mindlessness model by showing that with both types of tasks observers can utilize subtle regularities in the temporal structure of critical signal appearances to develop expectations about the time course of those appearances that affect performance efficiency. Such expectations enhance performance with the traditional vigilance task but degrade performance with the modified task.

Feature Presence/Absence Modifies the Event Rate Effect and Cerebral Hemovelocity in Vigilance Performance

Observers monitored displays of five circles for the presence or absence of a line in one of the circles during a 40-min vigil. Displays were updated 6, 12, or 24 times/min (event rate). Signal detections varied inversely with event rate when observers monitored for the absence of the distinguishing feature but not when monitoring for the presence of that feature and judged the workload of their assignment to be greater when monitoring for feature absence than presence. In addition, the availability of information processing resources, as indexed by transcranial Doppler sonography measurements of cerebral blood flow, was exhausted more rapidly when observers monitored for feature absence than for feature presence. This effect was limited to the right hemisphere. The results are consistent with the view that detecting feature absence is more capacity demanding than detecting feature presence and with previous brain imaging findings indicating right hemispheric control of vigilance.

Effects of Sensory Modality on Vigilance Performance and Cerebral Hemovelocity

Using Transcranial Doppler sonography, cerebral blood flow velocity (hemovelocity, CBFV) was recorded from the middle cerebral arteries during the performance of 40-min auditory and visual vigilance tasks. Reductions in stimulus duration were the critical signals for detection in both tasks, which were equated for stimulus salience and discrimination difficulty. Signal detection responses (correct detections and false alarms) and CBFV declined linearly over time in both modalities. In addition, the overall level of CBFV and the temporal decline in this measure were greater in the right than the left cerebral hemisphere. The results support the view that a right hemispheric system is involved in the functional control of vigilance and that this system operates in a similar manner in the auditory and visual channels.

Task-Induced Stress and Individual Differences in Coping

Coping is an important aspect of operator stress: people use various strategies for dealing with potentially stressful task demands. This paper outlines two studies of a new instrument designed for human factors applications, the Coping Inventory for Task Stress (CITS). Factor analysis of coping items differentiated three aspects of coping specified by stress theory: task-focus, emotion-focus and avoidance. Patterns of coping appear to reflect both task demands and individual differences in perceptions of workload. Relationships between coping and other stress-related variables were investigated in a study of subjects who performed a rapid visual information processing task. Task-focus and avoidance were sensitive to experimentally-manipulated task factors: time pressure and negative feedback. Coping also related to personality factors, as well as to the external pressures of the task. At a practical level, assessment of coping may contribute to understanding of how operators cope effectively or ineffectively with a variety of task-related stressors, leading to a more informed choice of countermeasures for stress.

The Effects of Emotional Intelligence on Visual Search of Emotional Stimuli and Emotion Identification

Emotional intelligence (EI) refers to competencies in processing and managing emotion that may be important in security settings; facial emotions may betray criminals and terrorists. This study tested the hypothesis that high EI relates to superior detection and processing of facial emotion, in relation to two tasks: controlled visual search for designated facial emotions, and identification of micro-expressions of emotion. Participants completed scales for EI, as well as cognitive intelligence, personality, and coping. EI failed to predict performance on either task, contrary to the initial hypothesis. However, performance related to higher cognitive intelligence, the personality trait of openness, and use of task-focused coping. These measures related to faster visual search, and to greater accuracy in detecting facial micro-expressions. Practical considerations suggest selecting security agents who are high in conventional rather than emotional intelligence, and training use of task-focused coping. However, EI may be useful for selecting stress-tolerant agents.

Demand Transitions and Tracking Performance Efficiency: Structural and Strategic Models

A compensatory tracking task with hard and easy levels of difficulty was used to test resource depletion and effort regulation models of dual-to-single task transition effects. Both models were supported by the data. Consistent with a resource depletion view, participants who shared the difficult tracking task with a vigilance task during an induction phase, and then performed the tracking task alone during a transition phase, had greater levels of tracking error in both phases than those who were confronted only with the tracking task. By contrast, in accord with expectations derived from the effort regulation view, tracking error on the easy task was smaller during both phases of the study for participants who originally shared tracking with vigilance than for those confronted only with the tracking task. Evidently, task difficulty is a key factor in determining the domains in which these models apply.

Time Perspectives Predict Mood States and Satisfaction with Life over and above Personality

The present study aimed to test the incremental validity of Time Perspective (TP) scales in predicting satisfaction with life and mood, over and above the Big Five personality traits. It also investigated whether the new TP construct of Future Negative perspective contributed to prediction of these outcomes. Participants (N = 265) completed four measures: Satisfaction With Life Scale (SWLS), UWIST Mood Adjective Checklist (UMACL), a modified Zimbardo Time Perspective Inventory (ZTPI), and NEO-Five Factor Inventory (NEO-FFI). Results confirmed the incremental validity of TP, although Big Five dimensions were independently predictive of life satisfaction and certain mood scales. Past Negative TP was the strongest single predictor of life satisfaction. However, Future Negative TP was be the strongest mood predictor from the TP universe, after controlling for the Big Five and remaining TP dimensions. Findings suggest that TP is an important aspect of personality for understanding individual differences in well-being.

The Impact of Automation Reliability and Operator Fatigue on Performance and Reliance

Reliability of automation is known to influence operator reliance on automation. What is less understood is how the influence of reliability and the effects of operator fatigue might interact. The present study investigated the impact of automation reliability on accuracy and reliance and how this impact changes with level of fatigue during simulated multiple unmanned aerial vehicle (UAV) operation. Participants ( N = 131) completed a two-hour simulated multi-UAV mission assisted by an automated decision making aid of either high or low reliability. A decrease in subjective task engagement and performance over time marked the induction of passive fatigue by the mission. Participants were more trusting in the high reliability condition than in the low reliability condition. Finally, reliance decreased with time at any reliability, but a significant interaction between reliability and time on task indicated that the decrease was of smaller magnitude when the automation was reliable.

Automation Reliability and Other Contextual Factors in Multi-UAV Operator Selection

Multi-unmanned air vehicle (UAV) operation requires a unique set of skills and high demand for new operators requires selection from populations without previous flight training. To support developing criteria for multi-UAV operator selection, the present study investigated the role of multiple individual difference factors in performance under different multi-UAV specific contexts. Specifically, we compared performance under fatigue using a high- and low-reliability automated aid. Accuracy on surveillance tasks, as well as reliance on automation were assessed. Video gaming expertise was associated with reduced stress and less reliance with a low-reliability automated aid. Distress was the most robust predictor of performance accuracy, but high distress was harmful only when reliability was low. Personality correlates of performance varied with both automation reliability and gender. Our findings suggest that multi-UAV operator selection should take into account the reliability of the automated systems.

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.

The Independence and Interdependence of Coacting Observers in Regard to Performance Efficiency, Workload, and Stress in a Vigilance Task

OBJECTIVE

We investigated performance, workload, and stress in groups of paired observers who performed a vigilance task in a coactive (independent) manner.

BACKGROUND

Previous studies have demonstrated that groups of coactive observers detect more signals in a vigilance task than observers working alone. Therefore, the use of such groups might be effective in enhancing signal detection in operational situations. However, concern over appearing less competent than one's cohort might induce elevated levels of workload and stress in coactive group members and thereby undermine group performance benefits. Accordingly, we performed the initial experiment comparing workload and stress in observers who performed a vigilance task coactively with those of observers who performed the vigilance task alone.

METHOD

Observers monitored a video display for collision flight paths in a simulated unmanned aerial vehicle control task. Self-reports of workload and stress were secured via the NASA-Task Load Index and the Dundee Stress State Questionnaire, respectively.

RESULTS

Groups of coactive observers detected significantly more signals than did single observers. Coacting observers did not differ significantly from those operating by themselves in terms of workload but did in regard to stress; posttask distress was significantly lower for coacting than for single observers.

CONCLUSION

Performing a visual vigilance task in a coactive manner with another observer does not elevate workload above that of observers working alone and serves to attenuate the stress associated with vigilance task performance.

APPLICATION

The use of coacting observers could be an effective vehicle for enhancing performance efficiency in operational vigilance.

Automatic-Controlled Information Processing and Error Detection in a Simulated Pharmacy-Verification Task

The relationships between attentional variables and information-processing demands of pharmacy dispensing tasks that contribute to difficulties in cognitive performance are not well-known. In the present study, a psychological approach to medical dispensing errors, the cognitive-systems performance model of Grasha, was employed to evaluate the contributions of individual differences in attention and alterations in visual task information on simulated pharmacy-verification performance, perceived workload, and self-reported stress. 73 college-age volunteers completed a pretest battery containing psychological measures of automatic and controlled information processing, and one-week later spent 265 min. completing the end visual-inspection process for 200 simulated prescriptions, 27% of which contained artificially inserted errors. Evidence suggesting that both automatic and controlled processes underlie performance of a simulated pharmacy-verification task was obtained. Individual differences in controlled information processing were mildly predictive of detection accuracy, while contrary to expectations, automatic processing scores did not produce significant relationships. Detection associated with experimental alterations in font size (12-pt. vs 6-pt.) of critical prescription label information was partially in line with expectations from the cognitive-systems performance model, while additional visual enhancements via a magnification/illumination device yielded mixed results. Finally, reports of perceived workload (NASA Task Load Index) and specific patterns of self-reported stress (Dundee Stress State Questionnaire) were consistent with a three-tier behavioral framework offered recently by Matthews, Davies, Westerman, and Stammers for predicting behaviors along the automatic-controlled continuum.

Personality and Disease: Correlations of Multiple Trait Scores with Various Illnesses

Correlations between personality measures and self-reported data on health status were examined in a sample of 5133 men and women, aged between 40 and 65. A wider range of diseases was studied than is typical. Small but theoretically meaningful correlations with personality were found for some diseases. Personality syndromes of Emotional Lability, Type A Behaviour, Behavioural Control, Locus of Control over Diseases and Psychoticism were distinguished factorially. Emotional Lability appeared to be the most robust predictor of general disease vulnerability. Some small but significant associations between specific illnesses and Type A and Behavioural Control were also found.