Accessing Meaning of Ambiguous Homographs Embedded within Sentences in Children with ASD

Comprehension deficiencies are problematic in individuals with autism, yet the cognitive atypicalities of these impairments are still not well understood. To date, evidence pertaining to the ability of children with Autism Spectrum Disorder (ASD) to process verbal information in context remains mixed, and has mainly focused on pronunciation tasks. This study investigates how children with autism can use meaning activation of word primes to disambiguate target homographs inserted in the context of sentences at automated (300ms) and controlled (1000ms) stimulus onset asynchronies (SOAs). Individuals with ASD and controls were presented with semantically related or unrelated primes for homograph targets. The current study compared reaction times and accuracy pertaining to the relatedness of the primes, while also exploring meaning activation at involuntary and voluntary stages of processing. ACCESSING MEANING OF HOMOGRAPHS 4 Table of Contents Abstract. 3 Acknowledgements.5 Introduction.6 Theory of Mind.6 Weak Central Coherence in ASD.7 Executive Function in ASD.9 Verbal Processing in ASD.11 Purpose of the study.17 Hypotheses.18 Method.19 Participants.19 Materials.20 Procedure.23 Results.25 Discussion.27 References.37 Tables.41 Figures.45 ACCESSING MEANING OF HOMOGRAPHS 5 Acknowledgements Firstly, I would like to express my sincere gratitude to my advisor Dr. Chris Klein for the continuous support of my thesis study for his patience, motivation, and immense knowledge. His guidance helped me in all the time of research and writing for this thesis. I could not have imagined a better mentor and advisor for my thesis study. This is the first study I have done on my own and all the feedback concerning insight to my project was extremely useful. He has made me a better critical thinker as well as a better researcher. Besides my advisor, I would also like to thank Dr. Barnas for being apart of my thesis committee. She has provided me insightful comments and encouragement, while also asking the hard questions. This incentivized me to widen my research from various perspectives and think about it in different ways. I thank every member of my fellow cohort for the late nights we spent in the lab, the time we spent together outside of class, and for all the fun we had in the last two years. We built great friendships together over the course of two years at Marietta College and these friendships will last a lifetime. Last but not least, I would like to thank my parents for supporting me during my two years at Marietta, throughout the writing of my thesis, and my life in general. ACCESSING MEANING OF HOMOGRAPHS 6 Accessing Meaning of Ambiguous Homographs Embedded within Sentences in Children with Autism Autism Spectrum Disorder (ASD) is a developmental disorder that is best represented by a two domain model concerning deficits in social communication and restricted and repetitive behavior/interests. (American Psychiatric Association, 2013). Considerable research focus has been directed towards the cognitive atypicalities that may account for impairments associated with ASD. The Theory of Mind (ToM) model (Baren-Cohen, Leslie, & Frith, 1985) proposes that autism is caused predominantly by an inability to represent mental states to one’s self and to others. Alternatively, others have proposed that deficits in autism are due to a weak central coherence (WCC) (Frith, 1989, 2003; Frith & Happe, 1994), or lack of executive functioning (EF) (Hughes & Russel, 1993; Oznoff, Pennington, & Rodgers, 1991). The commonality between these two accounts is the assumption that there is a core deficit in verbal processing in ASD. Individuals with ASD show a wide range of communication deficiencies often involving language comprehension. Currently, the cause of language comprehension deficiencies in individuals with ASD is still not fully understood. Comprehension depends on many cognitive processes, and can fail due to many reasons. The aim of this study was to examine the cognitive processes that underlie verbal comprehension abilities in persons with ASD. More specifically, the current study utilized semantic priming to assess the ability of individuals with ASD to use word meaning to disambiguate homograph word targets. Theory of Mind The Theory of Mind account proposes that individuals with ASD lack the tendency to be able to attribute mental representations to self and others in order to make predictions and explanations about behavior (Baren-Cohen, Leslie, & Frith, 1985). This theory is extremely useful in the study of child development because it provides a causal account that specifically ACCESSING MEANING OF HOMOGRAPHS 7 focuses on the impairments associated with ASD and tries to make links between the behavioral symptoms of ASD. It makes predictions concerning the deficits in areas such as communication, socialization, and imagination in individuals with ASD (Leslie, 1987). The main idea is that individuals with ASD lack the ability to “mentalize”, which called upon a mentalizing-deficit account to address the impaired and unimpaired communicative and social behaviors of individuals with ASD due to this “mind blindness. ” Impairments concerning the ToM can have profound impacts on the social relationships of children with ASD, as emotional and behavioral responses depend on understanding another person’s mental state. This model is powerful because it was the first to make fine predictions regarding the continuum of behaviors in individuals with ASD, and also explains the social and communicative behavior in these individuals compared to typically developing children. The main limitation of the ToM account is that it does not give a full explanation of ASD; more specifically, it lacks a complete framework for explaining basic cognitive differences in persons with ASD. The mentalizing account has provided a strong understanding concerning deficits in social interaction, and communication. However, this account cannot provide a clear explanation concerning non-social task and non-triad impairments based on the older DSM diagnostic criteria for autism such as restricted repertoire of interests, obsessive desire for sameness, and savant abilities. Additionally, research has also shown that some individuals with ASD can pass ToM measures consistently such as the Sally-Ann task and ordering pictures or stories involving mental states (Oznoff, Rodgers, & Pennington, 1991). For these reasons, two other models that account for cognitive impairments in individuals with ASD have been postulated. Weak Central Coherence in ASD ACCESSING MEANING OF HOMOGRAPHS 8 The WCC model (Frith 1989, 2003; Frith & Happe, 1994) makes an argument that people with ASD lack the natural propensity to process information in context at a global level. Rather, individuals with ASD integrate information on a more local level of processing. This claim provides a theoretical framework for the empirical findings of the increased ability shown by individuals with ASD on visuo-spatial measures that require detailed rather than global information processing as compared to typically developing individuals (Frith, 1989; Happe, 1994, 1996; Snowling & Frith, 1986). Many studies have contributed convergent evidence for children with ASD showing superior performance compared to typically developing children on tasks that require the ability to ignore global information, such as the Embedded Figures Test (Shar & Frith, 1983) and the Wechsler Block Design (Shar & Frith, 1983). Conversely, evidence from other studies show inconsistencies with the WCC model of autism, where no superiority of performance was found in children with autism in relation to typically developing children (Ozonoff, Pennington, & Rodgers, 1991). These inconsistent findings can best be understood by comparing evidence in which deficits do and do not occur. The studies that support evidence for failure of global processing often involve patterns of semantic deficiencies such as sentence processing (Happe, 1997) and semantic memory (Tager-Flusberg, 1991). Alternatively, the studies that fail to show differences between ASD and typically developing samples use visuo-spatial measures such as illusions (Ozonoff, Strayer, McMahon, & Filloux, 1994) or exposure to semantic information presented visually (Lopez &