UMD Theses and Dissertations
Permanent URI for this collectionhttp://hdl.handle.net/1903/3
New submissions to the thesis/dissertation collections are added automatically as they are received from the Graduate School. Currently, the Graduate School deposits all theses and dissertations from a given semester after the official graduation date. This means that there may be up to a 4 month delay in the appearance of a given thesis/dissertation in DRUM.
More information is available at Theses and Dissertations at University of Maryland Libraries.
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Item Pre-task planning time and working memory as predictors of accuracy, fluency, and complexity(2012) Nielson, Katharine Brown; DeKeyser, Robert; Second Language Acquisition and Application; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Working memory, which accounts for the ability to process information in the face of interference, is critical to second language acquisition (SLA) and use. The interaction of working memory capacity (WMC) with specific pedagogical interventions is a logical place for empirical SLA research, both to examine the cognitive processes underpinning second language performance and to identify instructional treatments that may differentiate learners based on their WMC. A good candidate for such an examination is planning time, a pedagogical intervention that has been the subject of extensive empirical research, which has, thus far, been largely unrelated to WMC. The study undertaken here considers WMC along with two different types of pre-task planning time (guided and unguided) as predictors of the accuracy, fluency, and complexity of learners' discourse. Ninety-two intermediate ESL students from seven classes at a community college participated in this study by completing two different working memory span tasks as well as two different "there-and-then" oral story-telling tasks. The treatment condition of the story-telling tasks was manipulated so that learners' performance could be considered in terms of provision of pre-task planning (± planning), type of planning (guided vs. unguided), and order of planning (planning first or planning second). The results demonstrate that the relationship among type of planning time, order of planning time, and WMC is complex. Task order had a clear effect on learners' production, regardless of the provision of planning time. When learners began the series of story-telling tasks under the + planning condition, their output on the subsequent, unplanned task varied according to whether they had first received guided or unguided planning time. In addition, guided planning time and unguided planning time also have very different effects on learners' production, with guided planning time promoting a focus on accuracy at the expense of complexity and unguided planning time fostering fluency. Finally, this study indicates that task conditions can affect learners with high and low WMC in different ways. Learners with high WMC are more likely to comply with complex story-telling instructions, improving their focus on grammatical form at the expense of fluency, whereas learners with low WMC are more likely to improve their fluency as a result of task repetition, regardless of the task conditions.Item WORKING MEMORY ASSESSMENT AND TRAINING(2011) Atkins, Sharona M.; Dougherty, Michael R; Neuroscience and Cognitive Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Working memory, the ability to maintain and manipulate information, is a core cognitive function important for everyday life. The capacity of working-memory differs across individuals, with working-memory capacity a reliable predictor of general fluid intelligence, verbal and mathematical abilities, and classroom achievement. However, research has been inconclusive on whether working-memory is a unitary domain-general construct, or multi-component domain-specific construct. Most theories had until recently thought that working-memory was a fixed ability; however, recent research suggests that working-memory is malleable and can be improved through cognitive training. These training-induced improvements have also been shown on untrained cognitive tasks, such as general fluid intelligence, attention, reading, and math. My research examines the structure of working-memory, validates newly designed web-administered working-memory assessments, and investigates the malleability of domain specific working-memory training.Item Structured Access in Sentence Comprehension(2011) Dillon, Brian William; Phillips, Colin; Linguistics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)This thesis is concerned with the nature of memory access during the construction of long-distance dependencies in online sentence comprehension. In recent years, an intense focus on the computational challenges posed by long-distance dependencies has proven to be illuminating with respect to the characteristics of the architecture of the human sentence processor, suggesting a tight link between general memory access procedures and sentence processing routines (Lewis & Vasishth 2005; Lewis, Vasishth, & Van Dyke 2006; Wagers, Lau & Phillips 2009). The present thesis builds upon this line of research, and its primary aim is to motivate and defend the hypothesis that the parser accesses linguistic memory in an essentially structured fashion for certain long-distance dependencies. In order to make this case, I focus on the processing of reflexive and agreement dependencies, and ask whether or not non-structural information such as morphological features are used to gate memory access during syntactic comprehension. Evidence from eight experiments in a range of methodologies in English and Chinese is brought to bear on this question, providing arguments from interference effects and time-course effects that primarily syntactic information is used to access linguistic memory in the construction of certain long-distance dependencies. The experimental evidence for structured access is compatible with a variety of architectural assumptions about the parser, and I present one implementation of this idea in a parser based on the ACT-R memory architecture. In the context of such a content-addressable model of memory, the claim of structured access is equivalent to the claim that only syntactic cues are used to query memory. I argue that structured access reflects an optimal parsing strategy in the context of a noisy, interference-prone cognitive architecture: abstract structural cues are favored over lexical feature cues for certain structural dependencies in order to minimize memory interference in online processing.Item Users' spatial abilities affect interface usability outcomes(2011) Campbell, Susan; Norman, Kent L; Psychology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The usability of a system depends both on inherent characteristics of the system and on its users. This paper argues that a major source of differences among users is variations in spatial ability, but that variations in different types of spatial ability affect components of usability differently. In two experiments, I investigated a simple model of the relationships of spatial visualization ability, spatial orientation ability, and spatial working memory with the usability constructs of efficiency and effectiveness. Both experiments used Wikipedia search as a representative information search task. The first experiment used a desktop computer interface, and the second experiment used a pair of mobile devices with widely different screen sizes. Better spatial orientation ability corresponded to faster performance on efficiency across devices. Better spatial visualization ability corresponded to slower performance on larger screens, but faster performance on smaller screens. Better spatial visualization ability also predicted better effectiveness in both experiments. These results suggest that spatial ability is a useful way to characterize users and to improve usability testing, and that its effects vary in systematic ways depending on characteristics of the tested interface and on which metrics are chosen.