Browsing Theses and Dissertations by Subject "Vision"
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THE ROLE OF VISION IN SCHOOL LEADERSHIPThe cornerstone of transformational leadership is vision. For our school leaders to act as more than middle managers, they have to foster a school community's vision - cultivate the school community's direction and purpose. This qualitative study uses semi-structured interviews with school leaders and following focus groups with their teachers to understand better how principals develop and instantiate their vision and how this vision is perceived to have manifested by the school community. This study was designed to answer the questions of (1) do principals have a clearly defined personal vision for the schools they serve, and in what ways do they enact their vision?, (2) what professional and training experiences contribute to how a principal develops a vision for a school?, (3) what the relationship between the articulated vision and the culture of the school? The four themes that emerged from this study were that ( 1 ) principals have guiding statements that serve the same purpose as a formal vision that gives them and their school communities direction for the work, (2) principals primarily invest their teams in a shared vision through a visioning process, (3) principals most cited avenue for vision development was through working with others, and (4) principals whose articulated vision most aligned with the culture of the school were successfully able to operationalize the vision. The recommendations and implications for all stakeholders from this research are that (1) principals are trained taught how to develop guiding statements, (2) principals are taught how to invest others in a shared vision, (3) the importance of mentor matching and principal reflection in the principal training and development process, and (4) principals are taught how to operationalize their vision through ongoing coaching and support.
VISUAL RECOGNITION OF THE STATIONARY ENVIRONMENT IN LEOPARD FROGSLeopard frogs (Rana pipiens) rely on vision to recognize behaviorally meaningful aspects of their environment. The optic tectum has been shown to mediate the frog's ability to recognize and respond to moving prey and looming objects. Nonetheless, atectal frogs are still able to appropriately respond to non-moving aspects of their environment. There appears to be independent visual systems operating in the frog: one system for recognizing moving objects; and another system for recognizing stationary objects. Little is known about the neural mechanisms mediating the recognition of stationary objects in frogs. Our laboratory showed that a retino-recipient area in the anterior lateral thalamus--the NB/CG zone--is involved in processing visual information concerning stationary aspects of the environment. This thesis aims to characterize the frog's responses to a range of stationary stimuli, and to elucidate the thalamic visual system that mediates those responses. I tested leopard frogs' responses to different stationary stimuli and found they respond in stereotypical ways. I discovered that leopard frogs are attracted to dark, stationary, opaque objects; and tested the extent of this attraction under different conditions. I found that frogs' preference to move toward a dark area versus a light source depends on the intensity of the light source relative to the intensity of ambient light. Unilateral lesions applied to the NB/CG zone of the anterior lateral thalamus resulted in temporary deficits in frogs' responses to stationary stimuli presented in the contralateral visual field. Deficits were observed in response to: dark objects, entrances to dark areas, light sources, and gaps between stationary barriers. However, responses to moving prey and looming stimuli were unaffected. Interestingly, these deficits tended to recover after about 6 days in most cases. Recovery time ranged from 2 - 28 days. The NB/CG zone is anatomically and functionally connected to a structure in the posterior thalamus called the "PMDT." The PMDT has no other connections in the brain. Thus, I have discovered a "satellite" of the NB/CG zone. Preliminary evidence suggests that the PMDT is another component of the visual system mediating stationary object recognition in the frog.
VISUAL WORKING MEMORY AND MOTOR PROCESSING CHANGES ASSOCIATED WITH EXPERTISE IN VISUAL ARTThe concept of novelty has important implications for theories of cognition, as familiar objects are categorically distinct from novel ones; accessing a stored representation of a known stimulus influences perception in a way that is precluded for a novel stimulus. The experiments that constitute this dissertation shed light on the perception-action cycle, as it is a persistent feature of human life; we see things and we act upon them. When those things are novel, how does cognitive processing change? Specifically, how do people who deliberately practice seeing things act upon them, and are there observable differences between trained and "casual" perceivers' perceptual processing? Some argue that any processing advantages possessed by experts are limited to objects or relations among objects within an expert's particular domain of expertise. However, a central point of contention revolves around what exactly constitutes a domain in the first place. Expertise may boil down to a long-term memory advantage for deliberately-practiced categories of stimuli, or to a heuristic that is only applicable to one trained goal or category of goals, or to a heuristic independent of task that can be applied to any novel situation. The present set of experiments examined visual cognition with the perceptual goal of fine-motor output (i.e., accurate sketching) as a candidate for a domain of expertise that confers advantages in visual perception in general. The extent to which visual processing is altered in expert visual artists was examined; whether they are more efficient only at sketching images of familiar stimuli, or whether their advantage extends to other visual cognition tasks. Familiarity and complexity of stimuli were manipulated, as were the goals of perception, including sketching and recognition. Finally, retention durations were manipulated before responses or sketches were made in order to examine the limits on experts' advantage on tasks that are known to tax the perceptual system. Results suggest that expertise in visual art confers a robust visual cognition advantage that generalizes beyond a narrowly-defined domain of expertise.