The daily, weekly, and unscheduled tasks for school administrators have increased in number and scope over the years, however surprisingly little is known about what principals do on a day-to-day basis and how this varies across schools. Since the effect of principal leadership behaviors, specifically how principals manage their time to accomplish important tasks, is one key to the success of schools, it is important to understand what effective principals do to accomplish this. The purpose of this study was to find out what the differences are in how principals in high and low-performing middle schools spend their time and to determine what relationships exist between the principal's time-on-tasks and school performance. In the literature review, the researcher identified seven categories of time use to collect and classify time-on-tasks data. The categories include: (a) administration/operations, (b) organization management, (c) day-to-day instruction, (d) instructional program, (e) internal relations, (f) external relations and (g) other (Horng, Klasik, & Loeb, 2010). The researcher collected time-on-tasks data from principals of high and low-performing middle schools in Virginia and analyzed the data to determine what relationships exist between the principal's time-on-tasks and school performance. Data analyses revealed that there are significant differences in the amount of time principals at high-performing schools devote to each of the time-on-tasks categories, as compared to the amount of time allocated by their counterparts at low-performing schools. In this study, principals as a whole and principals in the high-performing subgroup spend the largest percentage of time on tasks related to administration and operations, while principals in the low-performing subgroup spend the largest percentage of time on day-to-day instruction. Data also suggest that time spent on tasks related to internal relations is positively correlated with student performance on mathematics and reading tests. When demographic factors are combined with the time-on-tasks categories, a regression analysis suggests that the strongest contributing factor to mathematics and reading test scores is the socioeconomic status of the school with a strong negative correlation between the percentage of students on free/reduced lunch and test scores for mathematics and reading. / Ed. D.

The current research sets out to demonstrate a comprehensive approach to validate complex human performance models as applied to time-sensitive tasks. This document is divided into 4 sections. Section 1 (Chapters 1 – 3) outlines previous efforts in the literature that have attempted to validate complex human performance models in the field with an emphasis on manual control models, task network models, cognitive models and integrated architectures. Section 2 (Chapters 4 – 7) elaborates on a validation approach and applies it to a baseline model of a complex task in the air traffic control domain. Section 3 (Chapters 7-12) outlines the importance of adopting an iterative model development-model validation process and reports on the three model iterations in an attempt to improve the validity of the baseline model. Each model augmentation was validated using the same validation approach and measures that were defined in Section 2. Section 4 (Chapters 13-14) provides a discussion and interpretation of the model results and highlights contributions to the field of both model validation and the field of human performance modelling of complex systems.

The current research sets out to demonstrate a comprehensive approach to validate complex human performance models as applied to time-sensitive tasks. This document is divided into 4 sections. Section 1 (Chapters 1 – 3) outlines previous efforts in the literature that have attempted to validate complex human performance models in the field with an emphasis on manual control models, task network models, cognitive models and integrated architectures. Section 2 (Chapters 4 – 7) elaborates on a validation approach and applies it to a baseline model of a complex task in the air traffic control domain. Section 3 (Chapters 7-12) outlines the importance of adopting an iterative model development-model validation process and reports on the three model iterations in an attempt to improve the validity of the baseline model. Each model augmentation was validated using the same validation approach and measures that were defined in Section 2. Section 4 (Chapters 13-14) provides a discussion and interpretation of the model results and highlights contributions to the field of both model validation and the field of human performance modelling of complex systems.

Impairment of cognitive performance is often observed in time-on tasks. Theoretical considerations suggest that especially prefrontal cortex cognitive control functions is affected by time-on-task effects, but the role of effort/task engagement is not understood. We examine time-on-task effects in cognitive control on a neurophysiological level using a working-memory modulated response inhibition task and inter-relate prefrontal neuroanatomical region-specific theta-band activity with pupil diameter data using EEG-beamforming approaches. We show that task performance declines with time-on tasks, which was paralleled by a concomitant decreases of task-evoked superior frontal gyrus theta-band activity and a reduction in phasic pupil diameter modulations. A strong relation between cognitive control-related superior frontal theta-band activity and effort/task engagement indexed by phasic pupil diameter modulations was observed in the beginning of the experiment, especially for tasks requiring inhibitory controls and demanding high working memory. This strong relation vanished at the end of the experiment, suggesting a decoupling of cognitive control resources useable for a task and effort invested that characterizes time-on-task effects in prefrontal cortical structures.