Master of Science (MS), Wright State University, 2007, Human Factors and Industrial/Organizational Psychology MS

Traditionally, private communication channels with stable characteristics have been used in teleoperation situations. However, recently there have been a few attempts at using public communication channels such as the Internet. In spite of their convenience, very little is known about the effect of the variable delays inherent in this type of channel on motor performance. In this thesis, we provide empirical data on the impact of variable feedback delays on a 3D visual target-acquisition task performed in a virtual environment. Target size, distance between targets, mean feedback delay, and feedback-delay variability were manipulated and the number of errors and movement time (MT) were measured. Results showed that feedback-delay variability affected the closed-loop part of visual target-acquisition movements, even though its effect was weaker than the effect of mean feedback delay. Our results advise against using techniques that reduce feedback-delay variability at the expense of increasing mean feedback delay. In addition, we found that target size was critical for visual target-acquisition performance in the presence of feedback delays and this should be considered when designing teleoperation situations. Issues associated with studying feedback-delay variability are identified and lines of future research are suggested.

Committee: Robert Gilkey (Advisor) Subjects: Psychology, Experimental

Master of Science (MS), Wright State University, 2007, Human Factors and Industrial/Organizational Psychology MS

Previous research on aurally-aided visual search has repeatedly shown a significant reduction in response times when displaying 3D auditory cues. However, the vast majority of this research has only examined searches for static (non-moving) targets in static visual environments. In the present study, visual search performance in both static and dynamic (moving) visual environments is examined with and without virtual 3D auditory cues. In both static and dynamic environments, and for all observers, visual search times were significantly reduced when auditory spatial cues were displayed. Auditory cues provided the largest benefits when the target initially appeared at farther eccentricities and on the horizontal axis. General practice effects were observed, but 3D auditory cues were immediately effective with little or no time needed for learning. Overall, the results suggest a similar and consistent performance benefit offered by 3D audio for both static and dynamic environments.

Committee: Scott Watamaniuk (Advisor) Subjects: Psychology, Experimental

Master of Science (MS), Wright State University, 2006, Human Factors and Industrial/Organizational Psychology MS

This study examined active regulation of speed during a low-altitude flight task as a function of global optical flow rate, speed, and the presence or absence of a concurrent altitude disturbance. The results showed that altitude clearly had an impact on speed control; specifically, control of speed was much more difficult when altitude disturbances were present. Even in the no altitude disturbance conditions, performance tended to be best at lower altitudes. Consistent with previous research, the results suggest that speed and altitude changes have additive effects on speed judgments. This is inconsistent with the simple global optical flow rate hypothesis that had suggested multiplicative effects; however, it is consistent with the general notion that judgments of self-motion are based on properties of optical flow fields (i.e., angles and angular rates) that depend on distance and motion relative to textured surfaces.

Committee: John Flach (Advisor) Subjects: Psychology, Experimental

PhD, University of Cincinnati, 2000, Arts and Sciences : Psychology

It has been proposed that postural movements can be controlled so as to facilitate visual performance. Tasks that require more precise visual fixations should result in a decrease in postural sway variability. Three experiments were conducted that focused on (1) differences in postural behavior when tracking a moving versus stationary target, and (2) differences in postural behavior under constraints on visual performance theoretically unrelated to eye movements in a target detection task. In the first two experiments, sway variability was reduced when tracking a moving target relative to a stationary one. In the third experiment, sway variability was reduced when performing a more difficult target detection task, but only towards the latter part of the experiment. It seems that the functional relation between body sway and task demands developed over trials. Overall results suggest that postural behavior can be used to facilitate the achievement of other tasks. Results also suggest potential postural learning for more complex tasks to achieve adequate visual performance. Implications for the design of human-machine systems were discussed.

Committee: Thomas Stoffregen (Advisor) Subjects: Psychology, Experimental

PhD, University of Cincinnati, 2000, Arts and Sciences : Psychology

Motion sickness has been a problem for travelers and military personnel for quite some time. Improvements in vehicle technology and design have resulted in the reduction of motion sickness in the physical (vehicular) environment. However, with the development of virtual technologies, sickness has become increasingly common in non-vehicular situations. Unlike vehicular sickness, motion sickness produced by virtual environments (VE) is not alleviated by general improvements in VE technology. A theory of motion sickness developed by Riccio and Stoffregen (1991) asserts that sickness in real and virtual situations can be attributed to disruptions in postural control (stability). An initial test of the postural instability theory demonstrated that reports of motion sickness are preceded by gross disruptions in postural control (Stoffregen & Smart, 1998). In the current investigation, I studied relations between visually induced motion sickness and postural motion in two different venues. The goal of the research was to determine whether the indices used in Stoffregen and Smart (1998) were reliable and generalizable across different venues. A total of 27 participants were exposed to low frequency, sinusoidal motion. Half of the participants were exposed via a high fidelity virtual environment, the other half utilizing a moving room. Postural motion was measured using a magnetic tracking system (Flock of Birds, Ascension, Inc.), that recorded motion of the head. Pre-exposure and post-exposure symptomology data were collected using the Simulator Sickness Questionnaire (SSQ: Kennedy, et. al., 1993). Based on participants' subjective reports (i.e., whether they indicated that they were motion sick), the participants were separated into sick and well groups. A discriminant function analysis was performed in order to determine what factors functioned to classify participants into sick and well groups. Despite the differences in motion (translation/rotation), and differences in (open full item for complete abstract)

Committee: Thomas Stoffregen (Advisor) Subjects: Psychology, Experimental

PhD, University of Cincinnati, 2000, Arts and Sciences : Psychology

Future computers will be smaller and more mobile than modern computers. This change will require new ways of interacting with these systems. One possibility is to harness electroencephalographic (EEG) activity for computer control. Such devices exist, but all have limitations (Calhoun & McMillan, 1996; Wolpaw & McFarland, 1994; Sutter, 1984). Therefore, a novel EEG-based control was developed and tested. This system monitors the steady-state visual evoked response (SSVER), which is generated by a luminance-modulated (i.e. flickering) target. Selections are attempted by visually fixating one of multiple flickering targets presented by the system. A selection occurs if a SSVER is detected. To begin, Experiment I assessed operator performance, in addition to determining whether the SSVER was the locus of operator control. Operators were accurate and selection times were adequate. In addition, the results suggested that the SSVER was responsible for control. These results were encouraging; however, two issues were raised. First, participants fixated the target before initiating each selection attempt. Therefore, this study employed an atypical task, which did not require movement for selection. Second, these data do not address the relative effectiveness of this control compared to other conventional controls. Accordingly, a direct performance comparison between SSVER and mouse-based control was desired. Experiment II directly compared these controllers under more typical task constraints. Experiment II employed a variant of Fitts and Petersons' (1964) task, wherein target size and distance varied. Acquisitions were attempted with the mouse and the SSVER-based control. Performance was evaluated in terms of accuracy, speed, and fit to Fitts' law. Overall, accuracy was poorer and acquisition times were longer with the SSVER-based control. However, the level of performance attained by the SSVER-based control would be considered adequate when manual controls are problematic (open full item for complete abstract)

Committee: Joel Warm (Advisor) Subjects: Psychology, Experimental

MA, University of Cincinnati, 2007, Arts and Sciences : Psychology

When a person lightly touches an object with the fingertip, postural sway variability has been reliably shown to decrease. Two hypotheses have been proposed to explain why this reduction in sway variability occurs. The first, proposed by Jeka and Lackner (1994, 1995), concludes that sensory information available in light touch, resulting from stimulation of mechanoreceptors in the fingertip and the arm, is utilized to automatically reduce postural sway. The second hypothesis, proposed by Riley, Stoffregen, Grocki, and Turvey (1999), states that postural control is modulated by the demands imposed by the requirements to precisely control touching. The present experiment tested these competing hypotheses by manipulating the performance parameters of a light-touch task. The maximum level of allowable force produced when touching was manipulated. Producing more force presumably results in greater amounts of sensory stimulation, and, according to the sensory hypothesis, should be accompanied by reduced amounts of postural sway. In contrast, the supra-postural task hypothesis predicts the least postural sway in conditions involving the least maximum allowable force, because reducing the maximum allowable force increases the precision demands of the touching task. Forty-eight right-handed participants were randomly assigned to one of three maximum force production groups (0.75 N, 1.5 N, 2.25 N). Each participant completed five trials during which touching was performed as well as five no-touch control trials. Touch force was measured by the mean and SD of force production, measured using a force transducer, and postural sway was operationalized by the standard deviation (SD), local standard deviation (LSD; the average of SDs computed over non-overlapping, 1-second data windows), and path length of the center of pressure (COP) in both the medio-lateral (ML) and anterior-posterior (AP) directions, measured using a Bertec 4060 NC force platform (fingertip force and the COP we (open full item for complete abstract)

Committee: Dr. Michael Riley (Advisor) Subjects: Psychology, Experimental

PhD, University of Cincinnati, 2007, Arts and Sciences : Psychology

In a recent study by Gunn et al. (2005), participants simulating UAV controllers monitored a vigilance display for signals alerting them to the presence of enemy aircraft which they could then track down and destroy. A key finding in that study was the low workload rating that the participants gave on the NASA-TLX to the combined vigilance/tracking task. That finding contrasts with many previous investigations indicating that the cost of mental operations in vigilance is substantial, as reflected in high workload ratings on the NASA-TLX scale (Warm, Dember, & Hancock, 1996). In the previous studies, participants were typically required to detect signals without the need for subsequent action based upon their detections. The Gunn et al. (2005) study was the first to feature a detection/action link in which performance on a vigilance task had immediate consequences for actions to follow. The vigilance task could have taken on greater importance in this more dynamic context leading to lower ratings of perceived workload: A possibility that accords with the view that the manner in which participants interprets a situation may have impact upon the perceived workload of vigilance assignments (Hancock & Warm, 1989). This study tested that possibility along with three others under conditions in which UAV controllers were or were not afforded an opportunity to search/destroy enemy threats on the basis of successful signal detection on a monitored warning display. The results did not confirm Gunn et al.'s (2005) findings. Workload ratings in this study were in the upper level of the NASA-TLX scale in all cases except one, that in which participants only rated the search/destroy component of the detection/action composite. Nevertheless, the detection/action link did have significant effects upon the quality of vigilance performance and upon task-induced stress as measured by the Dundee Stress State questionnaire (Matthews et al., 2002). Participants who were afforded a detecti (open full item for complete abstract)

Committee: Dr. Joel Warm (Advisor) Subjects: Psychology, Experimental

MA, University of Cincinnati, 2007, Arts and Sciences : Psychology

Recent studies have indicated that postural control is not an automatic process; rather, postural control can be affected by the performance of a concurrent cognitive task (see Woollacott & Shumway-Cook, 2002, for a review). However, the literature is inconsistent regarding whether cognitive activity degrades or facilitates postural stability, the type of cognitive task used (e.g., vocalization), and the measures used to index postural sway. The aim of the project was to investigate the influence of a cognitive task (random number generation) on postural sway irrespective of any biomechanical influences of articulation using a dual-task paradigm. Thirty participants were instructed to perform simultaneously a posture task (standing upright) and a secondary task for which they were asked to either generate numbers randomly within a specified range at a given pace or to read corresponding numbers. Results revealed that some measures of postural sway may be differentially sensitive to cognitive demand while other measures appear to be influenced similarly by articulation and by cognitive demand. With an added cognitive demand, sway variability decreased, and nonlinear measures of postural sway found postural sway to be less auto-correlated and more random. These influences were not observed under speaking pace manipulations in speaking only conditions. These results suggest that certain measures of postural sway may be sensitive to cognitive influences, but not to influences of articulation.

Committee: Dr. Kevin Shockley (Advisor) Subjects: Psychology, Experimental

MA, University of Cincinnati, 2006, Arts and Sciences : Psychology

Perceived heaviness of wielded objects has been shown to be a function of the rotational inertia of the wielded objects—the objects' resistance to the rotational acceleration involved in wielding (e.g., Amazeen & Turvey, 1996). For example, if the resistance of an object to up-down wielding increases, the object will feel heavier. Streit, Shockley, Morris, and Riley (in press) hypothesized that the rotational inertia of a wielded object is optically specified by rotational kinematics—for a given applied force, the resulting motion is lawfully related to the resistance of an object to rotational acceleration. In support of their hypothesis, they demonstrated that if a virtual object rotates at a faster rate than the actual wielded object, the wielded object is perceived as systematically lighter and vice versa. Presumably, the visual (optically specified rotational inertia) and haptic (rotational inertia) sources of information are independent and additive sources that each directly map to perception (cf., Amazeen, 1999; Riley & Turvey, 2001). Seventeen participants estimated the heaviness of wielded objects. Rotational Inertia was manipulated by adjusting the position of a mass attached to the wielded object. Rotational kinematics were manipulated by applying a scaling factor to the rotational motion of virtual renderings of wielded objects—Rotational Gain. I predicted that perceived heaviness would be inversely proportional to Rotational Gain and proportional to Rotational Inertia. Results showed that both factors significantly influenced perceived heaviness, with no interaction. As predicted, Rotational Gain was inversely proportional to perceived heaviness and Rotational Inertia was proportional to perceived heaviness. The pattern of results supports the hypothesis of Streit et al. that rotational inertia can be detected both visually and haptically and that these sources of perceptual information may be perceptually independent.

Committee: Dr. Kevin Shockley (Advisor) Subjects: Psychology, Experimental

MA, University of Cincinnati, 2006, Arts and Sciences : Psychology

Transcranial Doppler sonography was used to examine the effects of the sensory modality of signals and event asynchrony on blood flow velocity (CBFV) in the cerebral hemispheres during the performance of a 40 –min vigilance task. Observers monitored pulses of light or sound for changes in duration under conditions in which the stimulus events to be scrutinized for the presence of critical signals occurred in a temporally regular (synchronous) or irregular (asynchronous) manner. Consistent with expectations derived from a sensory equivalence model of vigilance performance, overall signal detections and CBFV declined linearly over time in a manner that was independent of the sensory channels employed for stimulus delivery. Hemispheric differences in the overall decline in CBFV and in temporal changes in CBFV associated with the synchronous and asynchronous event conditions suggest that a cooperative interaction model may best describe the role of cerebral functioning in the control of vigilance performance.

Committee: Dr. Joel Warm (Advisor) Subjects: Psychology, Experimental

MA, University of Cincinnati, 2006, Arts and Sciences : Psychology

The utility of a new measure of perceived mental workload in vigilance, the Multiple Resources Questionnaire (MRQ), was evaluated by comparing it against a standard measure in that area, the NASA-TLX, in sensitivity to the effects of factors theoretically predicted to affect task demand, event asynchrony and search asymmetry (detecting stimulus presence/absence). Contrary to expectation, the former had little impact upon performance but the latter did; detection probability was significantly greater when critical signals for detection were defined by stimulus presence than stimulus absence. This effect was echoed in higher workload scores for absence than presence when workload was measured by the NASA-TLX but not by the MRQ, indicating poorer sensitivity for the new instrument. On the other hand, the MRQ did identify resources utilized in the vigilance task that are not reflected in the standard measure. Therefore, the new scale could be a useful adjunct to the older one.

Committee: Dr. Joel Warm (Advisor) Subjects: Psychology, Experimental

PhD, University of Cincinnati, 2005, Arts and Sciences : Psychology

Synergies have been widely recognized as a way the CNS functionally deals with the degrees of freedom problem (Bernstein, 1967). Results of previous research have suggested the CNS organizes groups of motor elements for context-specific tasks. Recently, the uncontrolled manifold (UCM) hypothesis has been developed to quantitatively detect the existence of synergies and asses the strength of synergies (Scholz & Schoner, 1999). According to this hypothesis a synergy exists when a desired value of a performance variable is preserved by structuring variability within a subspace (the UCM) of the multidimensional space composed of the motor elements (Varcomp) and minimizing variability in the subspace orthogonal to the UCM (Varuncomp). The UCM approach was applied to interlimb rhythmic coordination to determine if relative phase is stabilized as a control variable in both intrapersonal and interpersonal tasks and if the ratio of Varcomp to Varuncomp is affected by parameters associated with reduced coordination stability. Participants oscillated detuned or non-detuned pendulum pairs in either inphase or antiphase coordination modes at or above the coupled wrist-pendulum system's eigenfrequency. Experiment 1 employed an intrapersonal coordination task while Experiment 2 employed an interpersonal coordination task. Experiment 3 explored the effects of anchoring in within-person coordination. The results of all three experiments were consistent with the HKB model predictions (e.g., greater variability in antiphase, with the detuned pendulums, and when the metronome frequency was greater than the coupled wrist-pendulum system's eigenfrequency). The UCM analysis quantitatively verified synergies exist during a rhythmic motor task within a single person and between two people. Greater stabilization of relative phase was observed during inphase than antiphase coordination (Varcomp > Varuncomp) and, in Experiments 1 and 2, at the endpoints of the movement cycles. The latter effec (open full item for complete abstract)

Committee: Michael Riley (Advisor) Subjects: Psychology, Experimental

MA, University of Cincinnati, 2005, Arts and Sciences : Psychology

Recent evidence suggests that the postural control system and the cognitive system interact when engaged concurrently. However, the literature is inconsistent with regard to whether cognitive activity degrades or facilitates postural control, and with regard to whether distinct types of cognitive activity differentially affect postural control. The aim of this project was to assess the effects of working memory tasks on postural control. Participants were instructed to perform simultaneously a posture task and a working memory task, which varied across trials along three dimensions: a) type of information (verbal and visual), b) working memory component (phonological loop, visual sketchpad and central executive), and c) cognitive process (encoding and rehearsal). Results showed a general tendency for postural sway to decrease during rehearsal and to increase during encoding of cognitive information, but these effects were not specific to the working memory component that was presumably engaged by the verbal and visual tasks.

Committee: Michael Riley (Advisor) Subjects: Psychology, Experimental

MA, University of Cincinnati, 2004, Arts and Sciences : Psychology

The effects of task–induced stress and vehicle automation on drivers' performance efficiency and mood state were assessed. This combination of driving variables is likely to play a key role in automotive safety in the future as in-vehicle technology increases (Walker, Stanton & Young, 2001) and their effects may be synergistic (Matthews, 2002). Two levels of task induced stress (stress induction, no stress induction) were combined factorially with three levels of vehicle automation (free-driving, lead-following, automated-driving) to produce six experimental conditions (N = 28 per condition equated for sex). Participants in the stress induction condition were exposed initially to a simulated winter drive wherein they were subjected to episodes of loss of vehicle control due to an icy road. Participants in the no stress induction condition drove the same course, but were not exposed to such loss of control. Following the stress induction phase of the drive, all participants experienced a test phase in which they were required to drive a second course consisting of a single straight road. During that phase, participants drove in the automated condition to which they were assigned. Driver performance during the test phase was assessed both during single-task driving and a dual-task situation which required them to monitor the roadway for potential pedestrian hazards. Participants completed the Dundee Stress State Questionnaire (DSSQ, Matthews, et al.., 1999; 2002) a well-validated measure of subjective mood state that encompasses a modified version of the NASA-Task Load Index, a standard measure of the perceived mental workload associated with a task (Wickens & Hollands, 2000). The stress induction manipulation elevated participants' reports of distress and perceived workload, but had little effect on performance efficiency. In contrast, automation had a facilitative effect on driver performance in terms of deviations in lane position, longitudinal speed, and the numbe (open full item for complete abstract)

Committee: Dr. Gerald Matthews (Advisor) Subjects: Psychology, Experimental

MA, University of Cincinnati, 2004, Arts and Sciences : Psychology

Pilots of modern fighter aircraft encounter episodes of gravity-induced loss of consciousness (GLOC) consisting of complete unconsciousness and subsequent confusion. According to Whinnery, Burton, Boll, and Eddy (1987), pilots are totally incapacitated for 24 sec during such episodes. Current solutions to eliminate the GLOC hazard, including breathing and straining routines, anti-gravity pressure suits (G-suits), and reclined seatback angles, have proven not to be completely effective (Burton, Cohen, & Guedry, 1988; Tripp, 1990). It is conceivable, however, that with experience, pilots can learn to overcome the confusion and disorientation associated with GLOC and thereby, shorten the incapacitation time. Fourteen active duty members of the USAF (five women and nine men) participated in the study, conducted at the Air Force Research Laboratory's centrifuge facilities at Brooks and Wright Patterson Air Force Bases. Rapid G-onset rates of +3Gz/sec were used to induce GLOC in the participants on each of four testing days spaced one week apart. On each day, participants performed a compensatory-tracking task and a serial addition-subtraction math task concurrently for 5 min in a stationary centrifuge to provide baseline performance indices. They were also required to perform these tasks concurrently for as long as possible during +G-exposure and for 5 min following recovery from unconsciousness. The principal investigator and a flight surgeon, using real-time video images of participants and a protocol established by Whinnery et al. (1987), determined participants' entry and exit from GLOC. This study confirms the duration of total incapacitation described by Whinnery et al. (1987). It also indicates that the GLOC problem is more serious than they envisioned. Performance efficiency deteriorates from 3.20 to 7.44 sec prior to the onset of unconsciousness and does not return to baseline levels until 55.5 sec after the confusion phase has ended. Thus, at speeds of 500 mph (open full item for complete abstract)

Committee: Dr. Joel Warm (Advisor) Subjects: Psychology, Experimental

MA, University of Cincinnati, 2004, Arts and Sciences : Psychology

142 college students participated in a study of simulated driving. The aim of the study was to investigate situational and personality factors that may influence risk-taking in states of moderate stress and fatigue, within the general framework of the transactional model of stress. An attempt was made to induce a state of fatigue in half the participants, by forcing them to evade a series of other vehicles and pedestrians that threatened to collide with the driver. Following the induction, drivers were afforded opportunities to pass other traffic in risky circumstances. In fact, the fatigue induction proved to be ineffective: all participants, irrespective of experimental condition, tended to respond to the simulated drive with moderately elevated levels of distress and fatigue. By contrast, personality factors linked to aggression and anxiety were predictive of both subjective response and objective performance indices related to risk-taking, such as frequency of passing other vehicles. The investigation of personality focused on the role of coping, including both typical or dispositional coping style, and the situational coping elicited by the actual drive. Dispositional coping predicted increased subjective distress and worry, and loss of task engagement. Consistent with the transactional model of driver stress, the effect of dispositional coping was largely mediated by the situational strategies adopted in response to the specific situation. Task-focused coping appeared to be more adaptive than emotion-focused coping. Dispositional coping factors, especially a confrontive coping dimension, predicted risk-taking behaviors such as frequent passing. These effects were not mediated by situational coping, suggesting that emotions experienced during the acquisition of driving skills may shape habitual behavioral styles that operate irrespective of current mood and coping strategy. Implications of the findings for countermeasures to driver stress are discussed.

Committee: Dr. Gerald Matthews (Advisor) Subjects: Psychology, Experimental

MA, University of Cincinnati, 2003, Arts and Sciences : Psychology

The goal of this research was to understand how cognitive demand affects the process of acquiring adaptive hand-eye coordination. Endoscopic surgery, during which surgeons operate using video cameras and long, thin surgical tools, is an example of a situation that requires adaptive hand-eye coordination. In endoscopic surgery the normal mapping between the hands and the eyes is distorted, presenting a perceptual-motor challenge for surgeons and potentially causing a disruption in coordination. Besides having to adapt to altered perceptual-motor conditions surgeons also have to deal with many other simultaneous demands, such as monitoring vital signs. Having to perform other simultaneous tasks during endoscopic surgery may divert attention that is necessary for the complex movements demanded by the surgery. The specific aim of this study was to investigate whether adaptive performance in an endoscopic surgery simulator suffers under dual-task conditions. I investigated the effects of a concurrent short-term memory (STM) task on adaptation to visual-motor distortions encountered in an endoscopic simulator. Participants completed a peg transfer task in a low-fidelity endoscopic surgery simulator. In the pre-exposure and post-exposure phases participants moved small foam stars between pegs with endoscopic forceps while directly viewing the pegboard. In the exposure phase participants completed the peg transfer task while indirectly viewing the pegboard through a camera and monitor with a 90° clockwise visual rotation of the pegboard. A control group completed the experiment as described whereas an experimental group performed the STM task (mentally rehearsing a random string of digits) during the exposure phase. Performance was significantly disrupted under altered perceptual-motor conditions during early exposure-phase performance. The STM task caused an additional initial performance decrement, but experimental group performance quickly converged on control group perf (open full item for complete abstract)

Committee: Dr. Michael A. Riley (Advisor) Subjects: Psychology, Experimental

MA, University of Cincinnati, 2002, Arts and Sciences : Psychology

Although neuroimaging research has been successful in identifying brain regions involved in vigilance, such research has not related changes in the regions so identified to the efficiency with which observers perform the task. Thus, Parasuraman, Warm, and See (1998) have argued that the functional role of these brain systems in vigilance remains generally unknown. Mayleben et al. (1999) and Hitchcock et al. (in press) attempted to overcome the limitations of previous studies through the use of the Transcranial Doppler Sonography (TCD), a noninvasive neuroimaging technique that permits continuous monitoring of blood flow velocity in the mainstem intracranial arteries. Their research indicated that the vigilance decrement is accompanied by parallel declines in blood flow over time in the right hemisphere. These studies required observers to make sensory discriminations to detect critical signals. However, vigilance tasks can also require discriminations that are more symbolic than sensory in character. Such tasks are termed cognitive vigilance tasks (Davies & Tune, 1969). Nothing is known about blood flow changes with these types of vigilance tasks. Accordingly, this study measured TCD-determined blood flow during the performance of two cognitive tasks (simple and complex), as well as a sensory task. Blood flow in the right middle cerebral artery paralleled performance, indexed in terms of the accuracy of signal detections, for all three tasks, but not the speed of signal detections. Results are consistent with prior neuroimaging findings of right hemisphere dominance in vigilance, but not with arguments that signal detections and response time are equivalent measures of the same underlying process (Buck, 1966). In addition to blood flow measurements, this study also examined stress reactions to the cognitive as compared to the sensory vigilance tasks by means of the Dundee Stress State Questionnaire (DSSQ, Matthews et al., 1999). The results indicated that the cognit (open full item for complete abstract)

Committee: Dr. Joel Warm (Advisor) Subjects: Psychology, Experimental

PhD, University of Cincinnati, 2002, Arts and Sciences : Psychology

Vigilance or sustained attention tasks traditionally require observers to detect predetermined signals that occur unpredictably over periods of 30 min to several hours (Warm, 1984). These tasks are taxing and have been useful in revealing the effects of stress agents, such as infectious disease and drugs, on human performance (Alluisi, 1969; Damos & Parker, 1994; Warm, 1993). However, their long duration has been an inconvenience. Recently, Temple and his associates (Temple et al., 2000) developed an abbreviated 12-min vigilance task that duplicates many of the findings with longer duration vigils. The present study was designed to explore further the similarity of the abbreviated task to long-duration vigils by investigating the effects of signal salience and jet-aircraft engine noise on performance, operator stress, and coping strategies. Forty-eight observers (24 males and 24 females) were assigned at random to each of four conditions resulting from the factorial combination of signal salience (high and low contrast signals) and background noise (quiet and jet-aircraft noise). As is the case with long-duration vigils (Warm, 1993), signal detection in the abbreviated task was poorer for low salience than for high salience signals. In addition, stress scores, as indexed by the Dundee Stress State Questionnaire (Matthews, Joiner, Gilliland, Campbell, & Falconer, 1999), were elevated in the low as compared to the high salience condition. Unlike longer vigils, however, (Becker, Warm, Dember, & Hancock, 1996), signal detection in the abbreviated task was superior in the presence of aircraft noise than in quiet. Noise also attenuated the stress of the vigil, a result that is counter to previous findings regarding the effects of noise in a variety of other scenarios (Clark, 1984). Examination of observers' coping responses, as assessed by the Coping Inventory for Task Situations (Matthews & Campbell, 1998), indicated that problem-focused coping was the overwhelming copin (open full item for complete abstract)

Committee: Dr. Joel S. Warm (Advisor) Subjects: Psychology, Experimental