Browsing by Author "Gary Mirka, Committee Member"

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A Comparison of Knowledge Acquisition Methods for the Elicitation of Procedural Mental Models
(2002-12-19) Kahler, Susan; Gary Mirka, Committee Member; Katherine Klein, Committee Member; James Lester, Committee Member; Sharolyn Converse-Lane, Committee Chair
This study compared the effectiveness of two different knowledge acquisition methods in terms of their ability to measure the structure of a student's procedural mental model of computer programming as it evolved in a classroom setting over the course of a semester. Ratings and backward thinking tasks were used to estimate the structure of students' procedural mental models at several points throughout an introductory programming course. For both methods, comparisons between the student's procedural mental model and a prototype model (i.e., the instructor's conceptual model of the knowledge provided in the course) were used to identify how the procedural tasks and the relationships among tasks are represented in the student's mental model. The values from the ratings task were input into the Pathfinder scaling algorithm, which compares the structural similarity between a prototype model and the student's mental model, to generate an index of similarity. Additionally, the Pathfinder scaling algorithm measured the consistency of the student's rating process via the coherence index. The steps recorded during the backward thinking task were compared to the prototype model to identify the number of steps out of sequence. The first hypothesis was that there would be a positive correlation between the index of similarity and the project score. However, this hypothesis was only partially supported, as the correlation between the index of similarity and project score was significant only at test time three. The second hypothesis was that as the student completed each successive project, the index of similarity would increase over the course of the semester. This hypothesis was not supported because the index of similarity never increased beyond the value obtained at test time one. The third hypothesis was that as the student completed each successive project, the coherence index would increase. This hypothesis was not supported, as no main effect of test time on the coherence index was found. The fourth hypothesis was that there would be a negative correlation between the project score and the number of steps out of sequence. The number of steps out of sequence was excluded from further analysis due to low inter-rater reliability. Therefore this hypothesis cannot be evaluated. Lastly, it was hypothesized that the index of similarity would correlate more positively with student's performance than the number of steps out of sequence. Again, without the number of steps out of sequence, this hypothesis could not be fully evaluated. However, for project three, the index of similarity was significantly positively correlated with the project score.
Design and Prototyping of a Cognitive Model-based Decision Support Tool for Anesthesia Provider Management of Crisis Situations
(2006-08-21) Segall, Noa; Regina Stoll, Committee Member; Gary Mirka, Committee Member; Christopher Mayhorn, Committee Member; Melanie Wright, Committee Member; Robert St. Amant, Committee Member; David B. Kaber, Committee Chair
This research involved the prototyping of a decision support tool (expert system) for use by anesthetists in crisis situations, in order to promote prompt and accurate patient diagnosis, care, and safety. The tool alerts anesthetists to a developing crisis, manifested by changes in certain patient physiological variables, and provides them with a list of potential causes and preventive measures for dealing with the crisis. The tool provides advice in an unobtrusive manner. Information is presented in a format requiring minimal interaction with the system interface. Decision support tools for managing patient crisis situations may be useful in large hospitals where an attending anesthesiologist supervises multiple nurse anesthetists or anesthesiology residents that are delivering drugs to patients across operating rooms. Such a tool can provide support to nurses and residents when the attending physician is not present, and can warn of potential crisis situations that would prompt the anesthesia provider to contact an attending physician. The attending physician may also use the tool as a quick method of learning patient status when entering an OR. In addition, the tool could be used by practitioners working alone to deliver anesthesia. A novel approach was applied to the development of the decision support tool to support anesthesiology decision-making. First, a hierarchical task analysis was conducted to identify the procedures of the anesthetist in detecting, diagnosing, and treating a critical incident, specifically, myocardial infarction. Second, a cognitive task analysis was carried out to elicit the necessary goals, decisions, and information requirements of anesthetists during crisis management procedures. The results of these analyses were then used as bases for coding a cognitive model using GOMS (goals, operators, methods, selection rules), a high-level cognitive modeling language. EGLEAN (error-extended GOMS language evaluation and analysis tool), an integrated modeling environment, was used as a platform for developing and compiling the GOMS model and applying it to a Java-based simulation of a patient status display. After the anesthetist's decision-making process was captured in GOMS, a basic interface for the decision support tool was prototyped (extending traditional OR displays) to present output from the computational cognitive model by using ecological interface design principles. Finally, a preliminary validation of the tool and interface (patient state and cognitive model output displays) was performed with samples of expert anesthesiologists and human factors professionals in order to assess the usability and applicability of the decision support tool. The anesthesiologists indicated that they would use the decision support tool in crisis situations and would recommend its use by junior anesthesia providers. The human factors experts provided comments on the interface's compliance with usability principles, such as providing prompt feedback and preventing errors. This research has provided insight into anesthetist decision-making processes in crisis management. It resulted in a prototype of a cognitive model-based decision support tool to augment anesthetist decision-making abilities in these situations.
Development and Empirical Assessment of a Model of Situation Awareness for Multitasking with Locomotion
(2007-01-19) Sheik Nainar, Mohamed Ashraf Ali; David Kaber, Committee Chair; Simon Hsiang, Committee Co-Chair; Gary Mirka, Committee Member; Jason Osborne, Committee Member
Human locomotion has long been considered an overly practiced motor behavior. However, recent research has revealed a demand of locomotion on attentional resources, especially when performed during multitasking. Situation Awareness (SA), a cognitive construct critical to decision making and performance in complex tasks, has been shown to be important while multitasking with cognitive and physical workloads. No research has been conducted on the role of SA during locomotion with perturbations (e.g., slips and trips) and concurrent cognitive task performance (e.g., walking and talking on cell phone). The primary objective of this research was to develop a model of SA for multitasking with locomotion to conduct an empirical study to assess the validity of the proposed model for explaining proactive gait control in response to locomotion hazards. To support the empirical work, a virtual reality locomotion interface (VRLI) was developed to present walkers with realistic virtual locomotion environments (VLE) similar to everyday locomotion activities. An initial version of the VRLI consisted of a computer controlled treadmill, a head mounted display (HMD), and a graphical workstation running the VLEs and controlling the treadmill, based on participant movement using motion tracking sensors. The VRLI setup was validated through a pilot study that compared overground walking with treadmill walking in a VLE. Results showed similarities in walking characteristics between the conditions. Based on the pilot study, further enhancements were made to the setup. These included using a rear projection screen with a stereo projector and light-shutter goggles and a new treadmill with an embedded force plate (under the belt) for collecting gait ground reaction forces (GRF) and center of pressure (COP) data. Using the enhanced VRLI, an experiment was conducted to evaluate the utility of SA during locomotion and validate the proposed model of SA for proactive gait control for responding to locomotion hazards. In this experiment, the controlled variables included navigation aid type (NT), a priori knowledge (AK) and perturbation cueing (PC). NT consisted of two levels &8212; map-based navigation (MBN) and instruction-based navigation (IBN) and was manipulated between-subjects. AK consisted of three levels, low, medium and high, and was also manipulated between-subjects. The AK manipulation involved controlled the initial exposure of the walker to the test VLE and hence controlled their mental model development on the task environment. The low AK group was trained with a low fidelity VLE and medium AK and high AK groups were trained with a high-fidelity VLE, but only the latter group experienced a perturbation. The PC variable was manipulated within-subjects and it consisted of combinations of visual cueing and physical cueing of locomotion hazards forming four levels — visual only, physical only, visual plus physical and no cueing. Dependent variables measured included a battery of GRF and COP variables along with response accuracy to SA probes presented using a real-time probing technique. Twelve males and twelve females from the NCSU student population participated in the experiment and performed the navigation task following four different routes in the VLE. Results revealed participant proactive preparation for locomotion hazards, as observed through significant changes in GRF and COP measures. Effects included the nature of cueing of the perturbation and prior exposure to a trial with a perturbation involving visual cueing. There was also a complex interaction between NT, AK and PC that revealed greater participant proactive control during MBN with higher AK under visual plus physical cueing compared to IBN with lower AK under visual only cueing. SA accuracy under MBN was higher for probes requiring subjects to project VLE future states, as compared to IBN. Analysis of correlations between SA performance and gait response measures in five steps leading up to participants encountering perturbations revealed a negative relationship between SA and weight acceptance (at heel strike) with each step closer to the perturbation. The correlation was also significantly affected by the manipulated variables (list variables here in parentheses) and their higher order interactions. The study revealed that higher SA performance was associated with greater proactive control (decreased weight acceptance — flat footed walking). The results provided preliminary empirical validation of the proposed model of SA for multitasking with locomotion. Further experimental studies need to be conducted for a more fine grained investigation of the relationship of SA with specific proactive gait control mechanisms (e.g., accommodating, avoiding) under multitasking situations.
The Effects of Automation on Team Performance and Team Coordination
(2002-07-15) Wright, Melanie Clay; Michael G. Kay, Committee Member; David B. Kaber, Committee Chair; Gary Mirka, Committee Member; Sharolyn Converse Lane, Committee Member
The advancement of technology has led to an increased use of automation in a number of work domains, including team environments. However, assessment of the effects of automation on teamwork has been primarily limited to the aviation domain (comparing early conventional aircraft models with more advanced aircraft cockpits) and studies have produced conflicting information regarding the impact of automation on team performance, communication, and coordination. To more fully understand the implications of automation on system performance, researchers have begun to develop taxonomies and models of automation so that specific forms of automation can be defined and evaluated. A model proposed by Parasuraman et al. (2000) considers automation as it is applied to stages of information processing, including information acquisition, information analysis, decision selection, and action implementation. The objective of this research was to evaluate the effects of automation as applied to these different stages of information processing on the performance and coordination of teams in a complex decision making task. A simulated Theatre Defense Task in which teams protect a home base from enemy attack was used as a test-bed for this evaluation. Two team members were required to work together to share information in order to successfully complete the task. One team member monitored incoming aircraft on a radarscope and used missiles to shoot down enemy aircraft. A second team member monitored information provided by reconnaissance aircraft to classify the incoming aircraft as enemy or friendly. Four automation conditions were designed that compared different degrees of information acquisition, information analysis, and decision selection automation. Two levels of difficulty, determined by the number of aircraft presented, were used in the experiment. Dependent measures for the experiment included team effectiveness, quantity of team communication, team coordination ratings by outside observers, and task and team workload ratings. The results of the experiment revealed that different forms of automation have different effects on teamwork. Automation of information acquisition caused a decrease in the total amount of communication and an increase in the ratio of information transferred compared to information requested between team members. Automation of information analysis resulted in higher team coordination ratings. Automation of decision selection led to better team effectiveness under low levels of task difficulty but at the cost of higher workload. The fact that differing forms of automation had different influences on team performance in this research aids in explaining conflicting historical findings regarding the effects of automation on teamwork. The results of this research may have utility for the design of complex systems used in team environments.
An Investigation on the Interactivity between Suspended-load Backpack and Human Gait.
(2008-07-08) Xu, Xu; Simon Hsiang, Committee Chair; David Kaber, Committee Member; David Dickey, Committee Member; Gary Mirka, Committee Member
Using Surface Electromyography to Study Cervical Extensor Muscle Activity: An Investigation of Methodological Considerations and the Effects of Age on Fatigue Development and Recovery
(2002-08-19) Joines, Sharon Melissa Bennett; Gary Mirka, Committee Member; Sam Moon, Committee Member; James R. Wilson, Committee Member; Carolyn Sommerich, Committee Chair
The purpose of this research was to investigate the effects of aging on fatigue onset and recovery associated with low-level exertions of the neck musculature. This investigation into aging and fatigue is unique because the bulk of fatigue research has been performed at high force levels, and/or has not considered the effects of age on fatigue development. Several methodological issues were addressed in three preliminary phases of experimentation to develop a robust electromyography (EMG) collection/processing methodology that is sensitive to low level muscular fatigue. This new methodology was then employed in the investigation of the effects of age on the fatigue response of the neck musculature during low-level exertions. The first phase was an investigation of surface electrode location, using a structured neck marking procedure, and the underlying neck musculature, using ultrasound. The second phase of this investigation, a review of signal processing theory literature and a comparison of an ideal filter with a Butterworth filter, resulted in a set of recommendations for sEMG collection methods. The third phase of this investigation, an evaluation of the effect of neck posture during a maximum volunary contraction on normalized EMG values, showed that, there were significant differences between the sEMG data normalized using the posture specific normalization method and the reference posture normalization method. The final phase of this investigation identified measures for and evaluated the effect of age on fatigue onset and recovery due to a low force, static exertion held until fatigue. Based on the results of this experiment, it was found that: • there are several quantitative measures for identifying fatigue development associated with low-level exertions; • older subjects exhibited different fatigue response patterns compared with younger subjects; • some subjects regardless of age exhibited fatigue resistant characteristics; and • the recovery rate was not significantly affected by age group.