The Nature and Nurture of Canonical Babbling in Neurodevelopmental Disorders

Katie M. Belardi: The Nature and Nurture of Canonical Babbling in Neurodevelopmental Disorders (Under the direction of Linda R. Watson) An infant's language develops significantly during the first year of life. Language development is facilitated by an interaction between genetics and environment. Measures of vocalization development, such as canonical babbling and volubility, and the language environment (i.e., how parents respond) are important to study because they are affected by the interaction between biology and environment and may differentiate disordered populations from typical development. This dissertation includes two empirical studies. The purpose of study 1 is to determine whether there are differences in the canonical babbling and volubility (i.e., total syllables) between infants with fragile X syndrome and infants who are typically developing. Study 2 aims to determine whether parents of infants with fragile X syndrome, autism spectrum disorder and typical development respond to infant vocalizations with the same frequency and linguistic complexity. The information from these studies has the potential to inform our understanding of the early differences in language development in neurodevelopmental disorders. iv To the young ones-never lose your sense of wonder. v ACKNOWLEDGEMENTS