Theses and Dissertations from UMD

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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 give thesis/dissertation in DRUM

More information is available at Theses and Dissertations at University of Maryland Libraries.

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    The use of the domestic dog (Canis familiaris) as a comparative model for speech perception
    (2020) Mallikarjun, Amritha; Newman, Rochelle S; Neuroscience and Cognitive Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Animals have long been used as comparative models for adult human speech perception. However, few animal models have been used to explore developmental speech perception questions. This dissertation encourages the use of domestic dogs as a behavioral model for speech perception processes. Specifically, dog models are suggested for questions about 1) the role and function of underlying processes responsible for different aspects of speech perception, and 2) the effect of language experience on speech perception processes. Chapters 2, 3, and 4 examined the contributions of auditory, attention, and linguistic processing skills to infants’ difficulties understanding speech in noise. It is not known why infants have more difficulties perceiving speech in noise, especially single-talker noise, than adults. Understanding speech in noise relies on infants’ auditory, attention, and linguistic processes. It is methodologically difficult to isolate these systems’ contributions when testing infants. To tease apart these systems, I compared dogs’ name recognition in nine- and single-talker background noise to that of infants. These studies suggest that attentional processes play a large role in infants’ difficulties in understanding speech in noise. Chapter 5 explored the reasons behind infants’ shift from a preference for vowel information (vowel bias) to consonant information (consonant bias) in word identification. This shift may occur due to language exposure, or possessing a particular lexicon size and structure. To better understand the linguistic exposure necessary for consonant bias development, I tested dogs, who have long-term linguistic exposure and a minimal vocabulary. Dogs demonstrated a vowel bias rather than a consonant bias; this suggests that a small lexicon and regular linguistic exposure, plus mature auditory processing, do not lead to consonant bias emergence. Overall, these chapters suggest that dog models can be useful for broad questions about systems underlying speech perception and about the role of language exposure in the development of certain speech perception processes. However, the studies faced limitations due to a lack of knowledge about dogs’ underlying cognitive systems and linguistic exposure. More fundamental research is necessary to characterize dogs’ linguistic exposure and to understand their auditory, attentional, and linguistic processes to ask more specific comparative research questions.
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    Infant Speech-in-Noise Perception and Later Phonological Awareness: A Longitudinal Study
    (2008-10-20) Stimley, Sarah Elizabeth; Newman, Rochelle; Hearing and Speech Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    While differences have been found in the ability of infants on a variety of speech perception skills including speech perception in the presence of background noise, the implications of these differences on later language skills are currently unknown. This study examines the relationship between a specific measure of infant speech perception in noise and later phonological awareness outcomes. In order to test this relationship, individuals who participated in Newman's (2005) study on infant speech perception in the presence of background noise were administered a battery of language, phonological awareness, and intelligence tests. Scores from these tests were analyzed to see if performance differences existed between those who had performed well as infants in the original study and those who had not. No significant differences between these two groups were found on the phonological awareness measures. Potential reasons for these findings and suggestions for future research are discussed.
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    Brain Electrical Activity in Infants of Depressed and Anxious Mothers
    (2005-05-09) VanMeenen, Kirsten; Wigfield, Allan; Human Development; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Numerous studies suggest that positive and negative emotions are associated with different patterns of cerebral hemisphere activation and that specific patterns of electroencephalographic (EEG) asymmetry may indicate risk for depression and anxiety. The extant developmental psychopathology literature has examined patterns of EEG asymmetry in the offspring of parents with affective disorders and such research has reported linkages between frontal EEG asymmetry and depression, suggesting that measures of EEG asymmetry may be important neurological markers of risk for affective disorders. Despite the greater prevalence of anxiety disorders than depressive disorders and the literature suggesting that resting EEG asymmetry may serve as an index of both depression and anxiety, no research has yet examined patterns of EEG asymmetry in the offspring of parents with anxiety disorders. The purpose of the present study was to examine early markers of risk for psychopathology in the biological domain (e.g., patterns of EEG asymmetry) in an attempt to elucidate some of the precursors of anxiety and depression in children so that we might gain a better understanding of the development of these disorders. The present investigation examined the relation between maternal history of depression and anxiety and patterns of EEG asymmetry in infant offspring. EEG measures of alpha power (4-6 Hz) in the right and left hemisphere were recorded in infants (four to eight months of age) of mothers with a documented history of major depressive disorder (n = 39), anxiety disorder (n = 22), and comparison subjects (n = 38) during a resting baseline task. Results suggest that maternal depression and maternal anxiety was statistically unrelated to patterns of infant asymmetry. The results suggested that fewer infants of mothers with specific phobia (with and without depression) had right mid-parietal asymmetry than infants of control mothers. Perceived social support was related to patterns of infant EEG asymmetry. These findings provide modest support for the hypothesis that maternal diagnostic history may be related to patterns of infant asymmetry in various regions of the brain during a resting state.