Alexander D. Walker

The effects of 28 hours of sleep deprivation on respiratory sinus arrhythmia during tasks with low and high controlled attention demands.

Task performance while sleep deprived may be moderated by the controlled attention required by the task (Pilcher, Band, Odle-Dusseau, & Muth, 2007). This study examined the effects of 28 h of sleep deprivation on respiratory sinus arrhythmia (RSA) during tasks with low and high controlled attention demands. The results showed that RSA increased throughout the night for both task types, but was consistently reduced during the low compared to high controlled attention tasks. The increase in RSA was linear for the high controlled attention tasks but curvilinear for the low ones. Hence, RSA followed a circadian pattern during the low controlled attention tasks but not the high ones. These results suggest that the effects of sleep deprivation on task performance may be moderated by parasympathetic activity and task type, and this has implications for task assignment during sustained operations that cause sleep deprivation.

Respiratory sinus arrhythmia as a measure of cognitive workload

The current standard for measuring cognitive workload is the NASA Task-load Index (TLX) questionnaire. Although this measure has a high degree of reliability, diagnosticity, and sensitivity, a reliable physiological measure of cognitive workload could provide a non-invasive, objective measure of workload that could be tracked in real or near real-time without interrupting the task. This study investigated changes in respiratory sinus arrhythmia (RSA) during seven different sub-sections of a proposed selection test for Navy aviation and compared them to changes reported on the NASA-TLX. 201 healthy participants performed the seven tasks of the Navys Performance Based Measure. RSA was measured during each task and the NASA-TLX was administered after each task. Multi-level modeling revealed that RSA significantly predicted NASA-TLX scores. A moderate within-subject correlation was also found between RSA and NASA TLX scores. The findings support the potential development of RSA as a real-time measure of cognitive workload.

Effects of uncoupled motion on performance.

Objectives: To determine whether human exposure to vehicle motion specifically affects performance on a similar, yet uncorrelated, driving task and to observe the motion/simulator sickness symptoms that were associated with the real vehicle motion and the driving task. Background: Past research has shown uncoupled motion can affect a persons performance on a task as well as induce motion sickness. Methods: Ten participants (age range = 19-25 years) completed an uncorrelated driving task while seated in a stationary real vehicle and a moving real vehicle. Results: The results show participants took longer to complete the motion condition, t(9) = 1.96, p < .05, and were less accurate, t(9) = 3.73, p < .05. Scores for the Motion Sickness Assessment Questionnaire, t(9) = 3.37, p < .05, and the Simulator Sickness Questionnaire, t(9) = 3.30, p < .05, were significantly higher during the motion condition. Conclusions: Performance on the task was degraded and motion sickness heightened during the motion condition. Application: This research has potential implications for military-related tasks such as operating a command and control station or controlling a remote vehicle while simultaneously being a passenger in a real vehicle, as well as for civilian applications such as interacting with a moving map navigation system while driving a car.

Predicting Team Performance in a Dynamic Environment: A Team Psychophysiological Approach to Measuring Cognitive Readiness

Teams that operate in complex and dynamic environments must maintain a certain level of cognitive readiness among team members to ensure high levels of performance in response to potentially uncertain and time sensitive situations. In the current study, the authors sought to identify a physiological measure that could help predict team performance during a complex and dynamic task. Specifically, they examined whether measuring team members’ autonomic nervous system activity could predict subsequent performance on a dynamic process control task. Thirty-four teams of two (35 males, 33 females) completed a processing plant simulation during four varying levels of individual and team difficulty. Sympathetic and parasympathetic nervous system activity was measured throughout the task with an electrocardiogram and an impedance cardiogram and was combined to create a measure of team autonomic activity. Regression analyses showed that team autonomic activity accounted for 10% of the variance in team performance scores. In conclusion, the current study showed that team performance can be predicted from team autonomic activity, which supports the argument that a team’s physiological state could serve as an indicator of cognitive readiness.

Head movements and simulator sickness generated by a virtual environment.

BACKGROUND For virtual environments (VEs) to be useful in training it is important to understand the negative effects of VE exposure. The purpose of this study was to observe head movements in virtual and real environments and the relation between those movements and simulator sickness. METHOD There were 48 men who were trained in 4-person teams in either a head-mounted display (HMD)-based VE or in a real world environment. Head position data were collected in both systems and simulator sickness scores were collected in the VE. The relationship of head movements and sickness scores in theVE was examined and the degree of head movements in the real world and VE compared. RESULTS Differences were found in the length of time subjects spent moving their heads; subjects with the highest sickness scores moved their heads less often than other subjects in the VE. Also, subjects moved their heads significantly less and less often in the VE (means: 3 degrees x 50 ms(-1), 71% of trial time not moving head), compared to the real world (means: 10 degrees 50 ms(-1), 59% of trial time not moving head). CONCLUSIONS This study observed that when head movements are quantified, past assumptions of the link between increased sickness scores and decreased head movements may not hold. Though not linked to simulator sickness, head movements were reduced in the VE compared to the real world. Though observational in nature, this study is one of the first to quantify head movements and how they may relate to simulator sickness.

The Effect of Input Device on Performance of a Driving Task in an Uncoupled Motion Environment

Objective: To examine the effect of input device on performance of a driving task during uncoupled motion (UM). Background: Muth, Walker & Fiorello (2006) demonstrated that UM affected performance on a driving task with a steering wheel input device. However, it was unclear if the effect was due to general (motion sickness) or specific (interference with motor control) effects of UM. Methods: Ten participants completed a driving task while in a stationary and a moving real vehicle using a handheld control pad. Data were combined with the results of the previous study. Results: Regardless of input device, performance was significantly affected by UM, F (1, 18) = 16.69, p < 0.01, p2=0.48. There was also a condition by input device interaction, F (1, 18) = 4.81, p < 0.05, p2=0.21. Conclusions: This study demonstrated that UM can have both specific and general effects and that system design can potentially mitigate some of these effects.

The evaluation of virtual environment training for a building clearing task

This paper combines data from two experiments that evaluated the effectiveness of different virtual environments (VEs) for training the task of building clearing. 112 subjects were divided into 28 teams across two experiments. Each study consisted of 3 phases: lecture, team training, and testing in a real-world shoothouse. There were 6 training conditions: pc-based VE, helmet mounted display-based VE, real-world shoothouse, game console, single room real-world, and game console + single room real-world. The real-world shoothouse condition was the “gold-standard” against which test performances in other conditions were compared. An ANOVA was performed to compare test performance. There was a marginally significant main effect of performance across conditions, F(5, 22)=2.26, p<.07, ńp 2=0.34. The game console/single room real-world condition performed similarly to the “gold standard” and better than the next highest performing condition. These data provide some evidence that VE training could be utilized to augment real-world training rather than supplant it.