Kelly Satterfield

Using cerebral hemovelocity to measure workload during a spatialised auditory vigilance task in novice and experienced observers

This experiment was designed to assess cognitive load using transcranial Doppler sonography during the performance of a 40-min communication vigilance task in which messages were presented in different spatial locations or across a single monaural radio channel. In addition, some observers received 14 hours of practice to determine whether the neurophysiological measure was sensitive to a potential attenuation of workload. Critical messages were detected more frequently in the spatialised audio presentation mode condition, but there were no performance differences between experienced and novice observers. Neurophysiological data show that activation was greater in the novice condition than in the experienced condition, suggesting that novice observers expended greater effort. Furthermore, the neurophysiological measure showed more activation in the monaural radio condition than in the spatialised audio condition. The results support a resource account of vigilance and suggest that cerebral blood flow velocity can be used to diagnose the degree of attentional resource utilisation during vigilance tasks. Practitioner Summary: Due to high workload experienced during vigilance tasks, displays and methods are sought which enhance performance. This study shows that spatialising auditory communications in a monitoring task enhances performance and attenuates mental workload. Also, experience mitigates excessive workload, and cerebral hemovelocity can be used to diagnose attentional resource utilisation.

Measuring workload during a dynamic supervisory control task using cerebral blood flow velocity and the NASA-TLX

While automated systems have been shown to improve safety and efficiency in operational environments, automation failures can lead to abrupt shifts in workload. Subjective workload scales have been shown to be sensitive to differences in workload, but they are limited in their ability to assess dynamic, moment-to-moment workload variations. Physiological measures may be better suited to assess dynamic workload in complex environments. This study explored the feasibility of a relatively new physiological measure, Transcranial Doppler Sonography (TCD), as a candidate for adaptive automation studies. Participants performed long duration, supervisory control tasks under varying levels of taskload. In one group, enemy threats increased once late in the simulation, and in another group enemy threats increased at two points; once early and once late within the simulation. All participants completed a comparison condition in which there was no variation in the number of incoming enemy threats. Cerebral blood flow velocity (CBFV), as measured by TCD, was measured during task performance. Performance was assessed by the ability of the operator to protect a no-fly zone from enemy incursion. Subjective mental workload was assessed using the NASA-TLX. As performance decreased during periods of high load, CBFV increased, and there was a close parallel between the CBFV and performance measures. The NASA-TLX was sensitive in detecting differences in workload between the two conditions, but the patterns of results of this subjective measure were insensitive to specific task elements. The results are interpreted in terms of a resource theory of task performance and show that the CBFV measure is sensitive to dynamic changes in taskload in complex environments.

Cerebral hemovelocity reveals differential resource allocation strategies for extraverts and introverts during vigilance.

AbstractExtraversion—one of the Big 5 personality factors—correlates negatively with vigilance, but most studies focus on performance outcomes and not the performance process. Previous research has shown that transcranial Doppler sonography (TCD), which measures cerebral blood flow velocity (CBFV), can be used to examine resource allocation strategies during vigilance performance. Hence, this study was designed to assess the attentional resource allocation strategies of introverts and extraverts using the CBFV measure. Twelve extroverts and 13 introverts monitored a 60-min vigilance task for a critical signal—the absence of a line on a five-circle array. The results revealed an overall performance decrement that was not modulated by extraversion. We observed an interaction between extraversion and time; CBFV declined in the introversion group, but not in the extraversion group. Additionally, an interaction between cerebral hemisphere and personality revealed that extraverts were recruiting resources from both the left and right cerebral hemispheres, while introverts only recruited resources from the right hemisphere. The results suggest that extraverts can allocate compensatory effort to mask performance differences. We discuss the theoretical and practical implications of these findings and offer future research directions that may help us understand these effects.

Effects of the Multi-Modal Communication tool on Communication and Change Detection for Command & Control Operators

Due to the highly demanding and stressful mission set encountered by Command and Control (C2) operators, researchers at the Air Force Research Laboratory have developed a network-centric, multi-modal communication-monitoring suite. In previous studies, this tool has been shown to increase communication monitoring effectiveness and reduced workload for participants monitoring communication displays. However, in addition to communication displays, C2 operators often have the additional burden of monitoring tactical displays in order to create real-time representations of dynamic battlefield conditions. Creating this real-time picture is necessary to efficiently plan, coordinate, and control assets to accomplish mission objectives. This multi-tasking environment across different displays leaves C2 operators susceptible to missed information. The current study examined the performance and workload associated with monitoring both communication and tactical displays for critical information or changed events with varying communication management tools. Results indicated that the Multi-Modal Communication suite aided performance on both the communication and change detection task when compared with standard radio and chat displays. In addition, Multi-Modal Communication suite was found to reduce the perceived mental workload of this complex task.

Demonstration of a Network-Centric Communication Management Suite Multi-Modal Communication

The Multi-Modal Communication (MMC) is a network-centric communication management suite developed to improve communication performance for Command and Control operators. This tool provides operators with the ability to manage communication from voice and text-based systems in a single intuitive, dynamic display. MMC captures, records, and displays radio and chat communications to the operator so that they have instant access and full control over all current and past information. In addition to aiding in the retrieval of information, speech intelligibility over the Radio channels is increased by spatially separating each of the radio channels to virtual locations around the operator via their headphones. The combination of these features provides operators with the tools necessary to monitor multiple communication channels for critical information and make quick and accurate decisions since it affords operators with greater situational awareness while also reducing their perceived mental workload.

A comparison of subjective and physiological workload assessment techniques during a 3-dimensional audio vigilance task

The shift from platform-centric to network-centric warfare will require the use of sophisticated collaborative and communication technologies that can enhance shared situation awareness, thus improving military capabilities. However, the communication-intensive environment related with the use of these technologies may impose a high degree of mental workload as it is typical for operators to monitor and transmit on eight or more simultaneous channels. A net-centric communication management suite called Multi-Modal Communication (MMC) has been developed that offers a 3-dimensional spatial audio feature that can enhance the intelligibility of critical messages, but the workload associated with its use has not been thoroughly investigated. Twenty-two operators were assigned to monitor for the presence of critical phrases during a 40-min vigilance session with 6 different communicators in either a 3d spatial audio condition or a monaural radio condition. Cerebral blood flow velocity, a new index of mental workload, was measured during task performance and compared with a subjective measure of workload, the NASA-TLX. Results showed that there was a significant vigilance decrement over time, but that overall detection probability was higher in the 3d spatial audio than in the monaural radio condition. CBFV declined significantly over time, and a three way hemisphere x periods x presentation mode interaction revealed that CBFV was elevated during performance with monaural radio, but the decrement was most pronounced in the left hemisphere for the spatial audio task. Workload ratings from the NASA-TLX were insensitive to the differences in workload for the two task types. Results are interpreted in terms of a resource model of vigilance, and cerebral lateralization of vigilance and the potential limitations of subjective rating scales are discussed.

Assessing Resource Utilization during Vigilance Using Transcranial Doppler The Effects of Extraversion

Although automated systems have decreased the information-processing load on workers and have increased productivity, studies have shown that automation can have serious drawbacks, such as reductions in operator vigilance that can lead to decreased detection of critical events. Transcranial Doppler sonography (TCD) is a tool used to measure cerebral blood flow velocity (CBFV), and previous studies have shown that TCD can be used to examine attentional resource utilization and allocation during vigilance task performance. This study was designed to assess the attentional resource utilization of an individual difference measure that has shown to be associated with vigilance performance efficiency, extraversion. Twelve extraverts and thirteen introverts monitored a 60-min vigilance task for critical signals, which in this case, was the absence of a line on one of the five circles displayed on a computer monitor. CBFV and correct detections over six 10-min periods were used as the units of analysis. While a vigilance decrement was observed, there was no difference in detection efficiency between extraverts and introverts. The results pertaining to the CBFV measure reveal a significant hemisphere x personality interaction, such that the lateralization effect often present in vigilance was restricted to introverts. The results are interpreted in terms of findings suggesting that bilateral activation is a function of task difficulty: extraverts were recruiting mental resources from both the left and right cerebral hemispheres while introverts were using resources from only the right hemisphere. These findings suggest that the TCD measure is diagnostic of resource allocation associated with individual differences in vigilance.

Evaluation Tools to Aid Command and Control Operators in Chat-Based Communication Monitoring

Command and Control operators rely heavily on text-chat communications to efficiently plan, direct, coordinate, and control assets. This communication intensive environment imposes a high degree of workload on operators thus resulting in failures of detection or comprehension of messages. This study examined the performance and workload associated with monitoring chat communication with access to features that allow for speech-to-text input as well as the highlighting of keywords. Operators monitored and responded to the occurrence of critical signals presented during a 10-minute chat monitoring task. Performance was analyzed with regard to message detection as well as measures of perceived mental workload. Data showed that voice response results in more detections than typing and that keyword highlighting also aids in overall detection. Voice response and keyword highlighting can be beneficial tools to operators monitoring chat because they afford quick and accurate text input thus allowing operators to maintain awareness of their display and reduce their workload.

Using cerebral hemovelocity to measure workload in a complex vigilance task with display redundancy

Command and Control (C2) operators are responsible for monitoring multiple communication channels for long periods of time. One of the potential drawbacks of this important role is that these operators can experience a high degree of mental workload. The manner in which critical information is presented can influence the intelligibility, and thus, the workload of these tasks. To date, visual and auditory presentation of communication has been the primary focus of exploration regarding the manner in which critical information is disseminated to C2 operators. However, this research exploring auditory or visual only displays has been unsuccessful in preventing a performance decrement. Redundant displays may provide a solution. In this study, 45 operators monitored for the presence of critical phrases during a 40-min vigilance session with 1 of 3 different displays: auditory only, visual only, or a display with redundant auditory and visual information. Workload was measured using cerebral blood flow velocity (CBFV) and the NASA-TLX. Performance accuracy results revealed that the redundant display and visual only display facilitated more accurate performance than the auditory only condition, and that reaction times were faster for the redundant display condition than the visual only condition. Results pertaining to the physiological measure revealed that CBFV declined significantly over time, and a three way hemisphere x period x display condition interaction revealed that both hemispheres experienced a decrement in the visual and auditory conditions, but this effect was lateralized to the right hemisphere for redundant display conditions. Workload ratings from the NASA-TLX were insensitive to differences in workload for the different display conditions. Results are interpreted in terms of a resource model of vigilance performance and the cerebral lateralization of vigilance tasks.

Evaluation of advanced multi-modal command and control communication management suite

Command and Control (C2) operators function in communication intensive environments that impose a high degree of workload on them, thus resulting in failures of detection or comprehension of messages. To combat these issues, researchers at the Air Force Research Laboratory have developed an advanced network-centric communication management suite that aids C2 operators in their mission called Multi-Modal Communication (MMC). This system provides operators with the tools to manage communication in a single, intuitive, dynamic display that reduces perceived mental workload and aids in decision making and situation awareness. This study set out to evaluate the MMC tool as a communication management suite, which affords participants the ability to detect as well as comprehend the presentation of multiple critical messages. The use of the MMC tool resulted in more detections of critical messages and greater message comprehension, while also lowering ratings of perceived mental workload as compared to traditional communication tools such as radio and chat.