Matthew E. Funke

Cyber Vigilance: Effects of Signal Probability and Event Rate

Cyber security operators in the military and civilian sector face a lengthy repetitive work assignment with few critical signal occurrences under conditions in which they have little control over what transpires. In this sense, their task is similar to vigilance tasks that have received considerable attention from human factors specialists in regard to other operational assignments such as air traffic control, industrial process control, and medical monitoring. Accordingly, this study was designed to determine if cyber security tasks can be linked to more traditional vigilance tasks in regard to several factors known to influence vigilance performance and perceived mental workload including time on task, the probability of critical signal occurrence, and event rate (the number of stimulus events that must be monitored in order to detect critical signals). Consistent with the results obtained in traditional vigilance experiments, signal detection on a 40-minute simulated cyber security task declined significantly over time, was directly related to signal probability, and inversely related to event rate. In addition, as in traditional vigilance tasks, perceived mental workload in the cyber task, as reflected by the NASA Task Load Index, was high. The results of this study have potential meaning for designers of cyber security systems in regard to psychophysical factors that might influence task performance and the need to keep the workload of such systems from exceeding the information processing bounds of security operators.

The Sustained Attention to Response Task (SART) Does Not Promote Mindlessness During Vigilance Performance

Objective In this study, we evaluated the validity of the Sustained Attention to Response Task (SART) as a means for promoting mindlessness in vigilance performance. Background Vigilance tasks typically require observers to respond to critical signals and to withhold responding to neutral events. The SART features the opposite response requirements, which supposedly leads it to promote a mindless, nonthoughtful approach to the vigilance task. To test that notion, we compared the SART to the traditional vigilance format (TVF) in terms of diagnostic accuracy assessed through decision theory measures of positive and negative predictive power (PPP and NPP), perceived mental workload indexed by the Multiple Resource Questionnaire, and oculomotor activity reflected in the Nearest Neighbor Index and fixation dwell times. Method Observers in TVF and SART conditions monitored a video display for collision flight paths in a simulated air traffic control task. Results Diagnostic accuracy in terms of NPP was high in both format conditions. While PPP was poorer in the SART than in the TVF, that result could be accounted for by a loss of motor control rather than a lack of mindfulness. Identical high levels of workload were generated by the TVF and SART tasks, and observers in both conditions showed similar dynamic scanning of the visual scene. Conclusion The data indicate that the SART is not an engine of mindlessness. Application The results challenge the widespread use of the SART to support a model in which mindlessness is considered to be the principal root of detection failures in vigilance.

A Comparison of Cerebral Hemovelocity and Blood Oxygen Saturation Levels During Vigilance Performance

This study compared measures of cerebral blood flow velocity (CBFV) and blood oxygen saturation (rSO2), during the performance of a 40-min vigilance task. Observers monitored a simulated air-traffic control display for flight path deviations which occurred in a unidirectional or a multidirectional context. CBFV and rSO2 measures were secured from the medial cerebral arteries in the left and right cerebral hemispheres and from the corresponding frontal lobes, respectively. Performance efficiency was greater in the unidirectional than the multidirectional condition and declined over time in both conditions, more so in the multidirectional condition. This pattern of results was paralleled in different ways by the two hemodynamic measures. A result of this sort challenges the assumption of a close tie between cerebral blood flow and oxygen saturation (Siesjo, 1978) and supports recent findings (Mintun et al., 2001) that cerebral blood flow and oxygen levels are not tightly coupled in active brain states.

Effects of Stereoscopic Depth on Vigilance Performance and Cerebral Hemodynamics.

Objective: We tested the possibility that monitoring a display wherein critical signals for detection were defined by a stereoscopic three-dimensional (3-D) image might be more resistant to the vigilance decrement, and to temporal declines in cerebral blood flow velocity (CBFV), than monitoring a display featuring a customary two-dimensional (2-D) image. Background: Hancock has asserted that vigilance studies typically employ stimuli for detection that do not exemplify those that occur in the natural world. As a result, human performance is suboptimal. From this perspective, tasks that better approximate perception in natural environments should enhance performance efficiency. To test that possibility, we made use of stereopsis, an important means by which observers interact with their everyday surroundings. Method: Observers monitored a circular display in which a vertical line was embedded. Critical signals for detection in a 2-D condition were instances in which the line was rotated clockwise from vertical. In a 3-D condition, critical signals were cases in which the line appeared to move outward toward the observer. Results: The overall level of signal detection and the stability of detection over time were greater when observers monitored for 3-D changes in target depth compared to 2-D changes in target orientation. However, the 3-D display did not retard the temporal decline in CBFV. Conclusion: These results provide the initial demonstration that 3-D displays can enhance performance in vigilance tasks. Application: The use of 3-D displays may be productive in augmenting system reliability when operator vigilance is vital.

Stress and Workload Profiles of Network Analysis: Not All Tasks Are Created Equal

Effective cyber defense depends upon intrusion detection, i.e., the process of monitoring, detecting, and reacting appropriately to cyber activity threatening network security. Intrusion detection requires the execution of multiple unique, interdependent network analysis tasks. The current study aimed to expand understanding of cyber defense by separately assessing task induced workload and stress for two key network analyst tasks, triage analysis and escalation analysis, which are the first and second lines of cyber defense, respectively. In separate studies, participants assumed the role of either a triage analyst or an escalation analyst, performed associated intrusion detection duties in simulated cyber task environments, and reported task induced workload and stress. Findings suggest that, even though triage and escalation analysts are both engaged in cyber defense, their tasks result in differentiable workload and stress profiles. This highlights the need for further human factors research examining operator performance and state across network analyst roles.

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.

The Neuroergonomics of Vigilance: Effects of Spatial Uncertainty on Cerebral Blood Flow Velocity and Oculomotor Fatigue

Objective: The aim of this study was to examine the effects of uncertainty about where in the field of view critical signals for detection appear during a vigilance task (spatial uncertainty) on cerebral blood flow velocity (CBFV) and oculomotor fatigue. Background: Neuroergonomics is a dimension of human factors founded by Raja Parasuraman that studies brain functions underlying performance at work. Neuroergonomic studies have shown that observers in vigilance tasks lose information-processing resources over time and experience oculomotor fatigue as indexed by a temporal decline in CBFV and elevation in eye closure as reflected in the PERCLOS metric. Because spatial uncertainty increases an observer’s need for visual scanning relative to a spatial certainty condition, it was anticipated that spatial uncertainty would result in a greater temporal decline in CBFV and increased eye closure in a vigilance session. Method: Observers performed a simulated unmanned aerial vehicle (UAV) control task wherein collision flight paths were the events to be detected. UAV images could appear at random in any one of five locations on the controller’s display (spatial uncertainty) or only in a fixed location (spatial certainty). Results: Signal detection was poorer in the spatial-uncertain relative to the certain condition, and predictions regarding CBFV and eye closure were confirmed. Conclusion: Vigilance tasks involving spatial uncertainty are more neurophysiologically taxing than those in which spatial uncertainty is not a factor. Application: The neuroergonomic approach helps in understanding the effects of psychophysical factors in vigilance and to signify when performance aiding is needed.

Vigilance Hard Work Even if Time Flies

This study tested the possibility that the temporal context in which a vigilance task is performed will moderate the perceived workload of the task. We employed a procedure to manipulate participan...This study tested the possibility that the temporal context in which a vigilance task is performed will moderate the perceived workload of the task. We employed a procedure to manipulate participants’ perceived time progression (PTP) during task performance by creating a mismatch between their expectations about how long they would perform the task and the actual time they were engaged (Sackett et al., 2010). All participants worked at the task for 30 minutes. Those in a time drags condition were led to believe it would last 15 minutes while those in a time flies condition were told it would last 60 minutes. PTP was significantly slower in the former condition than in the latter. However, workload scores on the NASA Task Load Index were similar in the two conditions and fell at the upper level of the scale. Evidently, vigilance tasks are perceived as hard work even when time flies.

Team Vigilance The Effects of Co-Action on Workload in Vigilance

Operator vigilance is a vital concern to the Human Factors/Ergonomic community in regard to cockpit monitoring, air-traffic control, border security, baggage inspection, the supervisory control of unmanned aerial vehicles, and the monitoring of anesthesia gauges, among others. Of key interest is the performance of teams of observers because of the reliance of modern operations on good teamwork. Previous literature has examined the efficacy of team vigilance performance by comparing the frequency of target detections by teams in comparison to those obtained by operators working alone. Team performance has consistently exceeded singleoperator performance. The present study replicates this effect and provides the initial experimental investigation of the cost of being a team member. Results indicated that team members worked harder in terms of theta band activity, but reported similar subjective workload values when compared to that of single operators in the performance of a simulated UAV monitoring task.

Pedestrians’ perceptions of countermeasure efficacy in reducing risks at intersection crossings

The opinions pedestrians have regarding the efficacy of safety countermeasures and how these countermeasures impact an area’s walkability are currently not known. To address this gap in research 268 college students participated in a study to determine pedestrian appraisals of countermeasure efficacy at varying levels of intersection threat (determined by speed) and driver behaviors (safe, distracted, and aggressive). The authors developed a questionnaire instrument designed to assess pedestrians’ feelings of the efficacy of four types of safety countermeasure interventions: infrastructure design, increasing pedestrian control, traffic enforcement, and education. Results indicate that overall speed seems to have a greater impact on pedestrian perceptions of countermeasure efficacy than driver behaviors and pedestrians seem to report greater efficacy for countermeasures at higher speeds. Findings also suggest if a pedestrian views a countermeasure as effective that perspective persists across behaviors. Implications of the findings for pedestrian safety countermeasure design, increasing walking behaviors, and including pedestrian perceptions in assessments of an area’s overall walkability are discussed.