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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    Emotion & Prosody: Examining Infants' Ability to Match Subtle Prosodic Variation with Corresponding Facial Expressions
    (2008-12-04) Haszko, Sarah Elisabeth; Newman, Rochelle; Hearing and Speech Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Emotions are conveyed largely through facial expressions and prosody. One important part of language development is learning to express and comprehend these features of emotion. This study examined infants' ability to pair facial expressions with corresponding prosody for "happiness" and "fear". These emotions differ in valence but contain similar prosody. Sixteen-month-olds viewed a single video screen displaying either a happy or fearful facial expression. Simultaneously they heard a series of phrases containing either fearful or happy intonation. During some trials the voice and face expressed the same emotion; during other trials there was a mismatch. Infants' looking time was measured during each condition; they were expected to look longer when both the face and voice matched in emotion. Sixteen-month-olds did not look significantly longer during any particular condition. This suggests that infants may have a limited understanding of the manifestations of "fear" and "happiness" at 16 months of age.
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    The development of adaptive sensorimotor control in infant upright posture
    (2007-08-06) Chen, Li-Chiou; Clark, Jane E; Kinesiology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Postural control has been suggested as an important factor for early motor development, however, little is known about how infants acquire the ability to control their upright posture in changing environments and differing tasks. This dissertation addresses these issues in the first two years of life when infants learn to sit, stand, and walk. Three specific aims will be addressed: 1) to characterize the development of unperturbed infant upright postural sway; 2) to establish the influence of static somatosensory information on infant postural sway; and 3) to characterize the dynamic relationship between the infant's posture and sensory information. Three studies were conducted. The first study longitudinally examined infants' quiet stance and the influence of static touch in the 9 months following walk onset. With increasing walking experience, infants' upright postural sway developed toward lower frequency and slower velocity without changing the amount of sway. Additional touch information attenuated postural sway and decreased the sway velocity without affecting the frequency characteristics. We concluded that early postural development may involve increasing the use of sensory information to tune sensorimotor relationships that enhance estimating self-motion in the environment. The second study longitudinally characterized infants' unperturbed sitting postural sway and the influence of static touch. A temporary disruption of infant sitting posture was observed around walk onset. Light touch contact attenuated sitting postural sway only at this transition when infants' posture became unstable. These results suggest a sensorimotor re-calibration process in infant postural control to accommodate the newly emerging bipedal behavior of independent walking. The third study systematically examined the adaptive visual-postural dynamics, specifically the frequency- and amplitude-dependent features, in a cross-sectional sample of infants as they develop from sitting to standing and walking. The results revealed that infants as young as sitting onset were able to control their sitting posture responding to an oscillating visual stimulus as well as to re-weight the visual information as the stimulus amplitude changes. However, newly sitting infants, compared to experienced walkers, were more responsive but variable when the stimulus amplitude was small. We conclude from these three studies that infant postural development involves a complementary process between improving postural control of self-motion and an increasing sensitivity to environmental motion
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    The emotional modulation of the startle reflex in 9-month-old infants
    (2004-04-30) Marshall, Dalit Himmelfarb; Fox, Nathan A; Human Development
    The purpose of this research project was to investigate whether the startle reflex of 9-month-old infants can be modulated by emotional stimuli, as well as to examine the specific characteristics of infants' startle reactions in an emotion-modulated paradigm. Two studies were conducted to address these questions. In Study 1, 32 9-month-old infants viewed photographs of happy, neutral, and angry facial expressions. Infants' startle responses to acoustic probes during the presentation of the facial stimuli were recorded and compared across the three affective conditions. Autonomic and looking time data were also gathered in order to evaluate the contribution of other factors, such as attention, to the modulation of the startle reflex. The results of this study indicated a pattern of startle modulation opposite to that documented in adults. Infants demonstrated a potentiated startle reflex during the viewing of happy faces and an inhibited response during the viewing of angry faces. Differences in heart period and looking time between the affective conditions suggested that these findings were driven, at least in part, by greater allocation of attentional resources to angry expressions. To further examine the role of emotion in infants' startle modulation, an independent group of 25 9-month-old infants was tested in a second, modified emotion-modulated startle paradigm that involved the presentation of acoustic startle probes while infants were engaged in a pleasant game of peek-a-boo, an affectively neutral presentation of a spinning bingo wheel, and a mildly frustrating arm restraint episode. Autonomic and behavioral data were also gathered. As expected, the results revealed startle potentiation during the unpleasant condition and startle inhibition during the pleasant condition, indicating the existence of the emotion-modulated startle reflex in 9-month-old infants. Results of both studies are discussed in terms of the role of emotion and attention in startle modulation, the maturation of the appetitive and defensive brain systems in infants, and the importance of establishing a rigorous and age-appropriate startle paradigm to foster the study of infants' emotionality. Suggestions for further studies utilizing such a paradigm to investigate different aspects of emotional reactivity in infancy are also proposed.