Pitch in Autism Speech of Korean Children, Effect of Gesture in Artificial Grammar Learning, and Topic and Grammatical Complexity in Various Sources of Descriptions of Autism

Abstract

This dissertation investigates three aspects of communication relevant to Autism Spectrum Disorder (ASD): prosodic patterns in speech production, the role of gesture in language acquisition in people with varying traits related to ASD, and linguistic differences between clinical and lay descriptions of ASD-related behaviors. Chapter 2 examines pitch variability in Korean-speaking children with ASD compared to typically developing (TD) peers matched for expressive language age. Analysis of standard deviation and range in both raw pitch and semitone measurements revealed that TD children demonstrate significantly greater pitch variability than children with ASD. Additionally, these groups showed different developmental trajectories: TD children increased prosodic differentiation between declaratives and interrogatives as their language abilities developed, while children with ASD exhibited decreased pitch variability with increasing expressive language age. These findings in Korean, an understudied language in ASD research, provide evidence that atypical prosody may serve as a cross-linguistic marker for ASD. Chapter 3 explores whether gestures facilitate the acquisition of grammatical animacy and gender markers in an artificial language paradigm. Participants were assessed with AQ-10, a brief screening tool designed to quickly identify traits associated with autism spectrum conditions in adults. Contrary to predictions based on embodied cognition theories, results revealed no significant facilitative effect of gestures on learning these abstract grammatical categories. In fact, gestures appeared to hinder noun production in gender-related items and showed no significant benefit for animacy-related production. Additionally, AQ-10 scores were not meaningful predictors of performance. These findings challenge universal assumptions about the benefits of gestural input in language learning and suggest that the effectiveness of embodied approaches may be feature-specific and context-dependent. Chapter 4 analyzes linguistic differences between clinical and lay descriptions of ASD-related behaviors using computational linguistic methods. Lay descriptions received higher overall evaluation scores from clinical raters than clinical descriptions, particularly for certain diagnostic criteria. Grammatically, lay descriptions exhibited more complex structures with higher clause counts, while clinical descriptions demonstrated greater lexical diversity and vocabulary richness. These findings challenge traditional hierarchies of clinical versus lay knowledge and suggest that experiential narratives can effectively communicate clinically relevant information despite employing different linguistic strategies.Together, these studies are anticipated to advance our understanding of communication in neurodevelopmental contexts and have implications for ASD assessment, intervention approaches, and clinical communication practices.