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<p> Animal studies have shown that the tonotopic organization of the auditory cortex is not statically fixed, but can be remodeled by experience. The purpose of this study was to investigate whether or not frequency discrimination training can induce changes in the cortical representation of a selected frequency in humans. Six human subjects were trained for approximately 3 weeks to detect a change in pitch between two tones (40Hz amplitude modulated) using a standard frequency of 2040 Hz. Each subject was tested on his/her discriminative ability before and after training using three different standards (2040Hz, 1840Hz, and 2240Hz). EEG data were recorded both before and after training and changes in transient and steady-state responses were investigated. Behaviourally, every subject improved at the discrimination task using the trained frequency. However, only three subjects demonstrated transfer to both untrained frequencies. In the EEG data, the P2-Nl amplitude increased in five of the six subjects and the Nllatency decreased in all six for the 2040Hz set. These two findings were statistically significant (p<0.05) for the group. There were no statistically significant findings for the side frequencies. The change in the 40 Hz steady-state response was also not significant, increasing in three subjects and decreasing in the other three. These findings indicate that changes are expressed in the secondary auditory cortex. These findings may also be applicable to the treatment of tinnitus. </p> / Thesis / Master of Science (MSc)

Search and Rescue (SAR) operations are necessary during times of natural disaster or when individuals go missing. These missions mobilize individuals, both paid and volunteer, to find lost persons and are often carried out in treacherous areas. It is important for teammates to be focused and prepared. Specifically, the search coordinator's role and the head of command directing their teammates is vital to the outcome of a SAR mission. Their workload is significant, however, inviting the opportunity for autonomy to work in tandem with the search coordinator to ensure optimal, timely decisions are made for task scheduling. There has been a significant amount of investigation into task scheduling for human-autonomy teams, but there is a gap in the ordering methods used. One possible framework to investigate uses Rasmussen's SRK framework to classify individual responses to assigned tasks. There is also a significant body of work on this framework, but very little in a proactive task scheduling context. This thesis proposes a new approach to task scheduling utilizing Rasmussen's SRK framework. Scheduling tasks in this manner allows the characteristics of the tasks themselves to be considered as well as a more streamlined approach to reducing overall cognitive load for SAR teammates. An experimental study was conducted to determine the effectiveness of the proposed task scheduling methods based on the SRK framework. Initial results suggest there is an impact on scheduling tasks with respect to SRK, but further investigation is warranted to determine more specific factors. / Master of Science / Search and Rescue (SAR) operations are necessary during times of natural disaster or when individuals go missing. These missions mobilize individuals, both paid and volunteer, to find lost persons and are often carried out in treacherous areas. It is important for teammates to be focused and prepared. Specifically, the search coordinator's role and the head of command directing their teammates is vital to the outcome of a SAR mission. They have a significant number of responsibilities, however, inviting the potential for becoming overloaded with information and decisions. This does, however, suggest a significant opportunity for autonomy to work in tandem with the search coordinator to ensure optimal, timely decisions are made for task scheduling. There has been a significant amount of investigation into task scheduling for human-autonomy teams, but there is a gap in the ordering methods used. One possible framework to use to fill this gap is Rasmussen's Skill-Rule-Knowledge (SRK) framework to categorize and predict how individuals will respond to their assigned tasks. There is also a significant body of work on this framework, but very little in a proactive task scheduling context. This thesis proposes a new approach to task scheduling utilizing Rasmussen's SRK framework. Scheduling tasks in this manner allows the characteristics of the tasks themselves to be considered. In addition, the possibility of overwhelming SAR team members can be reduced by scheduling tasks intelligently. An experimental study was conducted to determine the effectiveness of the proposed task scheduling methods based on the SRK framework. Initial results suggest there is an impact on scheduling tasks with respect to SRK, but further investigation is warranted to determine more specific factors.

Work-related musculoskeletal disorders (WMSDs) remain a substantial problem in the workplace. Rotation, in which workers are rotated between tasks, is widely used as an administrative control, as it is considered to reduce WMSD risk through reducing physical exposures and increasing exposure variation. However, despite its widespread use, there is limited evidence that rotating between tasks is effective in reducing the risk of WMSDs. Inconsistencies in measured outcomes of rotation may be attributed to the variety of parameters involved in determining rotation schedules, including which tasks to include in a schedule, the rate at which workers rotate, and the order in which tasks are performed. This research assessed the effects of rotation, specifically focusing on rotation frequency and task order, on muscle fatigue and performance when included tasks loaded the same muscle group. Twelve participants completed six experimental sessions in each of three studies, during which repetitive tasks were performed for one hour either with or without rotation. Each study simulated a different task, including static shoulder abduction, box lifting, and a light assembly task. Rotation occurred between lower and higher exertion levels, and each rotation schedule varied in both rotation frequency (rotating every 15 minutes vs. 30 minutes) and task order (starting with the lower vs. higher intensity task). Muscle fatigue was assessed through several measures, including electromyography, and ratings of perceived discomfort. Performance was assessed through the accuracy of shoulder moment output, the accuracy of box placement, or the speed of assembly completion. As expected, rotation was effective in reducing fatigue compared to higher intensity tasks with no rotation, although it increased fatigue compared to the lower intensity with no rotation. While effects of rotation frequency and task order were seen on some measures, results across all three studies did not indicate consistent effects of either rotation frequency or task order on fatigue or performance. As such, the practical relevance of these rotation parameters and the likely impacts of rotation are not yet clear, and further assessments are needed. Such assessments should ideally involve longer durations, field studies, and/or more direct measures of injury or injury risk. / Ph. D.

The research objectives were (1) to perform a detailed review of the literature on speech recognition technology and the attentional demands of driving; (2) to develop decision tools that assist designers of in-vehicle systems; (3) to experimentally examine automatic speech recognition (ASR) design parameters, input modalities, and driver ages; and (4) to provide human factors recommendations for the use of speech recognition technology in automotive applications. Two experiments were conducted to determine the effects of ASR design parameters, input modality, and age on driving performance, system usability, and driver preference/acceptance. Eye movement behavior, steering input behavior, speed maintenance behavior, reaction time to forward scene event, task completion time, and task completion errors when driving and performing in-vehicle tasks were measured. Driver preference/acceptance subjective data were also recorded. The results showed that ASR design parameters significantly affected measures of driving performance, system usability, and driver preference/acceptance. However, from a practical viewpoint, ASR design parameters had a nominal effect on driving performance. Differences measured in driving performance brought on by changes in ASR system design parameters were small enough that alternative ASR system designs could be considered without impacting driving performance. No benefits could be claimed for ASR systems improving driving safety/performance compared to current manual-control systems. Speech recognition system design demonstrated a moderate influence on the usability of in-vehicle tasks. Criteria such as task completion times and task completion errors were shown to be different between speech-input and manual-input control methods, and under different ASR design configurations. Therefore, trade-offs between ASR system designs, and between speech-input and manual-input systems, could be evaluated in terms of usability. Finally, ASR system design had a nominal effect on driver preference/acceptance. Further research is warranted to determine if long-term use of ASR systems with less than optimal design parameters would result in significantly lower values for driver preference/acceptance compared to data collected in this research effort. Human factors recommendations for the use of ASR technology in automotive applications are included. The recommendations are based on the empirical research and the literature review on speech recognition technology and the attentional demands of driving. / Ph. D.

The purpose of this research was to investigate the relationship between employees' perceptions of their immediate supervisors' relations-oriented and task-oriented leadership behaviors and different types of organizational commitment. Bass & Avolio's (1995) Multifactor Leadership Questionnaire (MLQ Form 5X) was used to measure relations-oriented and task-oriented leadership behaviors. Meyer & Allen's (1997) Organizational Commitment Questionnaire (OCQ) was used to measure organizational commitment. Participants in the research included 361 employees who worked for the city of Charlottesville, Virginia. These employees were located in eight departments that varied in the area of technical functioning, size, and academic levels. Factor analyses, with principal component extraction and varimax rotation, were performed to determine how the MLQ Form 5X items would load onto a 2-factor model of relations-oriented and task-oriented leadership behaviors. The task-oriented items of contingent reward loaded with the relations-oriented items, and the non-leadership items of laissez-faire loaded with the task-oriented items. These findings resulted in an arrangement of relations-oriented and task-oriented subscales that was different than the arrangement proposed by Bass & Avolio (1995). Correlations for the MLQ Form 5X revealed multicollinearity among all the relations-oriented subscales and two of the task-oriented subscales, preventing any interpretations about the amount of variance that any particular type of relations-oriented or task-oriented leadership behavior might explain in organizational commitment. Factor scores were used to perform regressions and investigate the amount of variance relations-oriented leadership behaviors and task-oriented leadership behaviors explained in organizational commitment. Relations-oriented leadership behaviors explained the greatest amount of variance in affective commitment, somewhat less variance in normative commitment, and no variance in continuance commitment. The results for task-oriented leadership behaviors revealed the same pattern of relationships with the different types of organizational commitment, only weaker. / Ph. D.

This study replicated and extended existing research concerning task prioritization in multiple-goal scenarios. The theoretical perspectives on which hypotheses were based was a combination of Bandura's self-efficacy theory (1986) and rational models of control theory (Klein, 1989; Lord & Levy, 1994). Participants were 216 college students who received extra-credit points for their involvement. They performed six repeated trials on a computerized task consisting of two simultaneous sub-tasks. Participants pursued an assigned long-term goal on each task, and goal achievement was rewarded with additional extra-credit points as an incentive. Task prioritization was assessed with four separate measures of effort allocation, including the time spent on each task, the number of computer mouse-clicks made within each task, scores on a self-report assessment of exerted effort, and responses to a self-report task prioritization assessment. Results indicated that participants prioritized tasks on which they were closer to goal attainment, tasks on which they were more efficacious, tasks on which they were experiencing a faster rate of progress, and tasks on which they reported greater goal commitment. Results also indicated that the effect of goal-performance discrepancies (GPDs) on task prioritization was mediated by self-efficacy. Further the amount of time remaining before a deadline moderated the relationship between GPD and task prioritization, although the form of this relationship was not in the proposed direction. Achievement goals were examined as moderators of the relationship between GPDs and task prioritization, but results were non-significant. Overall, these findings provide additional evidence that expectancies are often central to understanding self-regulation in multiple-goal scenarios, as first asserted by Kernan and Lord (1990). The current study also provides additional evidence concerning the importance of temporal factors in determining resource allocation in multiple-goal scenarios. Results from the current study point toward multiple issues for exploration in future research, such as an integrated model focusing in part on the pivotal role of self-efficacy or other expectancy-related constructs. Results also demonstrate implications for applied work, including clear evidence that employees should be expected to allocate their finite resources toward goals on which they believe success is most likely. / Ph. D.