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Degree

PhD, University of Cincinnati, Arts and Sciences: Psychology, 2011.

Abstract

Neuroergonomics is an emerging field in human factors that studies brain functions underlying performance at work (Parasuraman, 2011; Parasuraman & Rizzo, 2007). The operational dimension featured in this study was vigilance or sustained attention which plays a major role in many automated human-machine systems. Two elements of the neuroergonomic approach, task-induced changes in cerebral blood flow velocity (CBFV, measured via transcranial Doppler sonography) and oculometrics (gaze control measured via saccadic frequency and dwell time and fatigue measured via blink frequency and duration, and eye closure) were used along with a measure of task-induced stress (the Dundee Stress State questionnaire, DSSQ, Matthews et al., 2002) to integrate the effects of a heretofore ignored psychophysical factor into the neuroergonomic and stress mosaic that underscores vigilance performance. That factor was spatial uncertainty or uncertainty as to where in the visual field critical signals for detection will occur. Observers assumed the role of an Air Force controller monitoring a squadron of four unmanned aerial vehicles (UAVs) flying in either a clockwise or counterclockwise direction during a 50-min vigil. Critical signals for detection were cases in which one of the vehicles was flying in an inappropriate direction relative to its cohorts. In a spatial uncertainty condition, images of the UAV squadron that needed to be inspected for the presence of critical signals could appear at random in any one of five locations on the controller’s display. In a spatial certainty condition, squadron images always appeared in a predetermined fixed location. Performance efficiency was found to be greater in the context of spatial certainty than uncertainty and to decline over time in both conditions. These performance effects were accompanied by a temporal decline in CBFV in the right hemisphere that was steeper in the presence of spatial uncertainty than certainty, a result consistent with the view that there is a right hemispheric system in control of vigilance (Warm, Matthews & Parasuraman, 2009). Visual scanning activity exhibited a temporal decline in saccadic frequency and an increase in fixation duration, indicative of temporally based reductions in active visual sampling, but these changes were not consistently more evident in the spatial uncertainty context. Ocular measures of fatigue were found to increase over time in both cases, and were significantly greater in the spatial uncertainty context in terms of blink frequency and the percentage of eye closure. Based on the DSSQ scores, observers found their vigilance assignment to be stressful as reflected in a loss of task engagement and an increase in distress over the course of the vigil. These effects however, did not differ in the spatial certainty/uncertainty conditions The results of this study were considered in relation to the utility of a resource model in accounting for the effects of spatial uncertainty and task duration on vigilance performance and stress, and in relation to the use of the hemodynamic, oculomotor, and DSSQ stress measures to determine when operators may be in need of rest or replacement and to predict operator performance efficiency.

Subject Headings

Psychology

Keywords

neuroergonomics; cerebral hemovelocity; ocular activity; vigilance; spatial uncertainty; stress

Committee / Advisors

Gerald Matthews, PhD (Committee Chair)
Chung-Yiu Chiu, PhD (Committee Member)
Michael Riley, PhD (Committee Member)
Joel Warm, PhD (Committee Member)

Pages

123p.

Document number: ucin1313773072
Permalink: http://rave.ohiolink.edu/etdc/view?acc_num=ucin1313773072

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