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A longitudinal study of lexical development in young children with autism spectrum disorders Peralejo, Jenea 2008

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A LONGITUDINAL STUDY OF LEXICAL DEVELOPMENT IN YOUNG CHILDREN WITH AUTISM SPECTRUM DISORDERS  by JENEA PERALEJO  B.A. Ateneo de Manila University, 2002 D. Ling, The University of British Columbia, 2005  A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE in THE FACULTY OF GRADUATE STUDIES (Audiology and Speech Sciences)  THE UNIVERSITY OF BRITISH COLUMBIA (Vancouver)  April 2008  © Jenea Peralejo, 2008  Abstract 0B  Children with Autism Spectrum Disorders (ASD) have deficits in communication and delays in language development, but there have been few studies of their vocabulary. This study compared longitudinal parent report data from the MCDI collected for 49 children with ASD over three years with data from the MCDI norms. It focused on three aspects of lexical development: (1) change in lexical composition as evident in percentage of predicates/nominals; (2) order of emergence for predicate types and (3) predictive value of lexical variables for later grammatical development. ASD Groups were matched to typically developing group norms on total MCDI scores for each comparison. Subsequent analysis indicated: (1) no differences in the percentages of predicates/nominals for the two groups at 3 time points; and, (2) virtually identical orders of emergence for different predicate types with the exception of three meaning type categories—quantitative predicates, cognitive/affective predicates and predicates involving causal acts to change experiential states. Cognitive/affective predicates were found to come in somewhat later in ASD groups while quantitative predicates and predicates involving changes in experiential states came in earlier in ASD groups. This study also found (3) that lexical variables, especially number of predicates, strongly predicted grammatical complexity one year later, a process common in typical language development. The study concludes that lexical development in ASD follows the normal course, albeit later and more slowly. It also suggests that communication deficits in this population are rooted in challenges with social acts rather than from an inability to match meanings to words.  ii  TABLE OF CONTENTS Abstract ............................................................................................................................... ii List of Tables ...................................................................................................................... v List of Figures .................................................................................................................... vi Acknowledgements ........................................................................................................... vii CHAPTER ONE: BACKGROUND OF THE STUDY...................................................... 1 Literature Review............................................................................................................ 1 Overview of Autism Spectrum Disorders ................................................................... 1 Language Development in ASD ................................................................................. 4 Lexical Development in ASD ..................................................................................... 9 Typical Vocabulary Development ............................................................................ 14 Goals of the Present Study ............................................................................................ 18 CHAPTER TWO: METHODS ......................................................................................... 19 Overview ....................................................................................................................... 19 Participants .................................................................................................................... 19 Typically Developing Group .................................................................................... 19 ASD Group ............................................................................................................... 20 Measures ....................................................................................................................... 22 MacArthur-Bates Communicative Development Inventories (MCDI) .................... 22 Childhood Autism Rating Scale (CARS) ................................................................. 24 Mullen Scales of Early Learning .............................................................................. 25 Data Preparation............................................................................................................ 25 The Proportion of Nouns to Predicates ..................................................................... 25 Predictive Value of Predicates for Later Grammatical Development ...................... 28 Order of Acquisition of Predicate Types .................................................................. 30 Summary ....................................................................................................................... 34 CHAPTER THREE: RESULTS ....................................................................................... 35 Overview ....................................................................................................................... 35 Question 1: The Proportion of Nouns to Predicates ..................................................... 35 TD and ASD Group Comparisons ............................................................................ 35 Post hoc Analyses ..................................................................................................... 39 iii  Question 2 : The Predictive Value of Early Predicates for Syntactical Development.. 41 Correlational Analysis .............................................................................................. 42 Multiple Regression Analysis ................................................................................... 42 Question 3 : The Order of Emergence of Lexical Predicates ....................................... 43 TD Group .................................................................................................................. 43 ASD Group ............................................................................................................... 45 Comparative Analysis ............................................................................................... 48 Summary ....................................................................................................................... 52 CHAPTER 4: DISCUSSION............................................................................................ 53 Overview ....................................................................................................................... 53 Discussion of Research Findings .................................................................................. 54 Question 1: Change in Lexical Composition (Proportion of Nouns and Predicates) 55 Question 2: Predictive Value of Predicates .............................................................. 61 Question 3: The Order of Emergence of Predicate Types ........................................ 63 Summary of Findings ................................................................................................ 69 Relevance of Findings to Theory: What Do We Now Know About ASD? ................. 69 Implications for Future Research .................................................................................. 73 Replication of Findings from Current Study ............................................................ 73 Future Areas of Lexical Research in ASD ................................................................ 74 Implications for Clinical Practice ................................................................................. 75 References ......................................................................................................................... 77 APPENDIX A ................................................................................................................... 94 APPENDIX B ................................................................................................................. 103 APPENDIX C-1 .............................................................................................................. 109 APPENDIX C-2 .............................................................................................................. 110  iv  List of Tables 1B  Table 2.1 ASD Group Specifics at T1 .............................................................................. 22 Table 2.2 ASD and TD Groups Matched on Mean Total Vocabulary Size ..................... 26 Table 3.1 Average Proportion of Predicates and Nominals Reported as Spoken in ASD and TD Groups .......................................................................................................... 36 Table 3.2 Proportions of Nominals and Predicates in Low, Mid and High Vocabulary ASD Groups .............................................................................................................. 40 Table 3.3 Low ASD Group and TD Groups Matched on Mean Total Vocabulary Size .. 40 Table 3.4 Correlation Coefficients between Independent Variables at T1 and Syntax Development at T2 .................................................................................................... 42 Table 3.5 Age of Emergence of Spoken Predicate Types in Typically Developing Children..................................................................................................................... 44 Table 3.6 Order of Emergence of Predicate Types in TD and ASD Groups .................... 49 Table 3.7 TD and ASD Early Emerging Words from Predicate Categories .................... 50 Table 4.1 Summary of Research Findings ........................................................................ 69  v  List of Figures 2B  Figure 3.1 Average Proportion of Predicates and Nominals in ASD and TD Groups Over Time .......................................................................................................................... 37 Figure 3.2 Vocabulary Size Growth in ASD and TD Groups Over Time ........................ 38 Figure 3.3 Proportions of Nominals and Predicates in Low ASD Group and Re-Matched TD Groups ................................................................................................................ 41 Figure 3.4 Development of Predicate Types in ASD Group at 4 Time Points ................. 45 Figure 3.5 Order of Predicates Types Based on Total Number of Predicates Acquired .. 47  vi  Acknowledgements 3B  To Dr. Judith Johnston, my supervisor, who has given so much time to this project, shared so many wonderful ideas, and inspired me to strive to be a great thinker. On behalf of every student you’ve ever had…thank you for the stories, lessons, laughter… there aren’t enough predicates in my lexicon to express how much you’ve meant to all of us! To Pat Mirenda and Karen Bopp, my committee members, who provided me with this data and who have always supported and encouraged me to keep going onward and upward! Thank you. To all who volunteered on this project, especially Fiona and Melissa. Thank you for spending a summer of data entry with me! To all my friends and family, especially my sister Cris, the one who has taken care of me through the ups and downs, and in spite of everything, is still here… I couldn’t do this without you.  vii  For all the dreamers out there who thought they might, found out they could, and surprisingly did… this is for you.  viii  CHAPTER ONE: BACKGROUND OF THE STUDY 4B  Communication development in autism has been a focus of study over the years, yet many specific domains of language development in this population remain unexplored. It is the goal of this study to address one particular area of language acquisition—lexical development. Surprisingly few studies have looked at this aspect of communication in young children with autism and even fewer have done so with longitudinal data. The main goal of the study will be to address the question: How does the lexical development of children with autism match up to that of typically developing children? To do so, it will longitudinally compare three common trends found in the lexical development of typical children to that of children diagnosed with autism. This paper will include four chapters detailing the specifics of the study including research goals, methodology, results, and a discussion of the relevance of the results. The upcoming initial chapter will set the background for the study and will include two major sections—a review of the relevant literature and the goals of the study. The literature review will present an overview of autism, followed by a summary of what is known on the general language development of children with autism, and trends in typical lexical acquisition. The chapter will end with a summary of the specific goals and research questions that the study will address. Literature Review 13B  Overview of Autism Spectrum Disorders 30BU  Autism has become one of the most widely recognized developmental disorders. A recent study reviewed surveys done on the prevalence of autism spectrum disorder (ASD) and found that 1 in 200 people in Canada have this diagnosis (Fombonne, 2003). 1  The number of Canadian children with this diagnosis is even higher, with prevalence estimated at 0.6% or 1 in 165 children (Fombonne, Zakarian, Bennet, Meng, & McLeanHeywood, 2006). These numbers only seem to be increasing as awareness and understanding of the disorder grows. Given the growing prevalence of this disorder, there has been a push to increase our knowledge of what ASD entails. Finding such answers has been difficult given the nature of the disorder—as a spectrum, individuals with the diagnosis can vary greatly from one another. For instance, it is common to see children who are completely nonverbal diagnosed with ASD. It is equally standard to see children with the very same diagnosis talking fluently but lacking in social pragmatic knowledge. With such variability, the DSM IV-TR has emerged with a definition and some basic criteria for diagnosis. According to this manual, children with ASD have symptoms in the following three areas: 1) social interaction, 2) communication, and 3) restricted, repetitive and stereotyped patterns of behavior, interests or activity (American Psychiatric Association, 2000). With such a broad and complex range of symptoms, there has been no lack of research on the causes and background of how ASD can present in such a wide array with varying levels of severity. A recent review of research on the etiology of this disorder found that there is growing support that ASD is largely genetically determined (Vitiello & Wagner, 2007). Involving multiple genes, it presents in a variety of ways depending on which genes or combinations of genes are involved (McCauley et al., 2005). Ongoing research is being conducted to confirm which specific genes are associated. Aside from looking at ASD from a genetic perspective, recent research has also found interesting  2  trends in the physiological development of children later diagnosed with ASD. They are said to have excessive head growth in the first year of life, but a deceleration in head growth in their second year, a time when clinical manifestations of the disorder begins to become apparent (Dawson et al., 2007). Despite these interesting findings, more research linking physiological growth and behavioral characteristics of this disorder are needed to allow for better overall understanding of the causes and nature of the disorder for earlier diagnosis. Aside from research to focus on the nature and etiology of the disorder, there has been much discussion and debate with regard to how to approach treatment for families and children with such a diagnosis. Knowing that ASD affects a young child’s development in three major areas—social interaction, communication, and restrictive/repetitive negative behaviours— current treatment research has focused on providing early intervention and the importance of involving a variety of team members. Treatment approaches have included a wide continuum of methods ranging from the behaviorist practices to social-pragmatic and developmental ones (Prizant & Wetherby, 1998). A recent survey conducted in the United States found that primary intervention service providers were using as many as 30 different treatments, but were rarely analyzing the research base for the programs they implemented (Stahmer, Collings, & Palinkas, 2005). Despite the many treatment options available, evidence based treatment practices have not yet been established, as intervention research has not been able to develop significant means to assess outcomes from treatments (Prizant & Wetherby, 1998). Given that research has not established a thorough understanding of the nature of the disorder coupled with the fact that ASD includes a wide range of deficits in three core  3  areas of development, it is not surprising that more research is needed in how to approach treatment. Despite this rather bleak picture, there is one area of treatment for individuals with ASD that seems to be emerging as an integral part of an intervention program— speech and language therapy services. A survey, conducted worldwide with 7% of the respondents representing Canada, found that out of 111 possible intervention approaches, the most common treatment provider working with children with ASD was the SpeechLanguage Pathologist (SLP) (Green et al., 2006). This is not surprising given the nature of the disorder as having one of its core deficits in the area of communication and language. Language Development in ASD 31BU  Despite the important role SLPs have in intervention plans for children with ASD, many SLPs do not have a thorough understanding of how language develops in children with ASD. The upcoming section will present current research trends that have been explored in this field as well as sum up what is known regarding the general language profiles that characterize this population. Current Research in Language Development of Children with ASD 5B  Current research has largely focused on early communication at the preverbal level and has emphasized the importance of these acts on later language development. Bono and colleagues (2004) found that joint attention skills such as using eye gaze, pointing or verbal comments with another individual to communicate about a toy or event, were associated with greater language development in children with ASD (Bono,  4  Daley, & Sigman, 2004). A more recent study involving young children with ASD found that motor imitation, along with joint attention skills, both predicted later growth in expressive vocabulary, but joint attention acts were the sole predictor for later vocabulary comprehension (McDuffie, Yoder, & Stone, 2005). Another study found that both number of hours of SLP services received and motor imitation skills in two year olds with ASD predicted expressive vocabulary at the age of four (Stone & Yoder, 2001). A longitudinal study by Smith and colleagues (2007) found three early predictors of later vocabulary growth in children with ASD—number of words prior to intervention, presence of verbal imitations and use of objects to pretend, and the number of gestures used to initiate joint attention (Smith, Mirenda, & Zaidman-Zait, 2007). Aside from predicting vocabulary development, joint attention skills have also been found to be related to later learning grammatical abilities in children with ASD (Rollins & Snow, 1998). Joint attention and other early preverbal acts such as motor and verbal imitation have all been established as important foundational elements for later language and communication development in this population. This is certainly an important piece of information for any professional working with children with ASD because it provides a starting point for many early intervention teams. Most of this research however, mainly focuses on early social interaction deficits in children with ASD and although this is certainly tied together with deficits of communication, it does not provide SLPs with direct information about the actual progression of language development in these children.  5  Research on the Language Profiles of Children with ASD 56B  In general, it has been observed and that many children with ASD are often very slow to acquire words and multiword utterances, and will speak very little until later in the preschool years (LeCouteur, Bailey, Rutter, & Gottesman, 1989). However, there is some degree of variability with the research that has been found on the language development of these children—with some studies finding relative preservation of language skills and others finding that language skills are very severely delayed. What is commonly agreed upon is that language acquisition in ASD is variable given the subgroups of individuals within the spectrum (Paul, Chawarska, Klin, & Volkmar, 2007). Deficits in Language Abilities. One study that aimed at creating a broad language U  U  profile of children with ASD sampled 44 children ranging in age from 4 to 14 and administered several standardized and non-standardized language measures (Condouris, Meyer & Tager-Flusberg, 2003). They found that, overall, average scores on standardized measures (Clinical Evaluation of Language Fundamentals, Peabody Picture Vocabulary Test-Third Edition, & Expressive Vocabulary Test) assessing lexical and morphosyntax abilities were more than one standard deviation below the mean. They found comparable results when analyzing spontaneous speech samples through SALT (Systematic Analysis of Language Transcripts), MLU (Mean Length of Utterance), NDWR (a measure of lexical diversity) and IPSyn (an alternative measure of syntactic and morphological development). MLU and NDWR scores were found to be two standard deviations below the mean in the SALT reference database. These results confirmed that both lexical and morpho-syntactic development in children with ASD are below age-level expectations.  6  Some researchers have found that the broad language problems in children with ASD are not limited to their expressive abilities. Charman and colleagues (2003) found that, in preschool aged children with ASD, the comprehension of words lagged behind their expressive abilities as measured through scores on MCDI parent report checklists. The combination of these receptive language delays with their characteristic deficits in verbal abilities add support to the already existing notion that overall language abilities are disordered in children with ASD. Relative Preservation of Language Skills. Some researchers suggest that even U  U  though communication deficits are a defining characteristic of ASD, and language is very commonly delayed amongst these children, early deficits in specific language domains are not universal in ASD (Paul et al., 2007). For instance, Tager-Flusberg (1981) reviewed several studies completed on the syntactic, phonological, semantic, and pragmatic development of children with ASD and found that the research agreed that both syntactic and phonological abilities followed the general pattern of typically developing children, but at a slower rate while semantics and pragmatics were found to be deficient. More recently, researchers sampled 89 children diagnosed with ASD found a quarter of this sample to have relatively “normal” scores on several standardized language measures. In addition, amongst verbal children with ASD, basic form and content of language were comparable to that of mental-age-matched peers, with some exceptions in the area of words involving social knowledge of others’ internal states (Kjelgaard & Tager-Flusberg, 2001). Given this, recent researchers have been interested in examining what characteristics in specific language domains may be preserved or deviant in children with ASD.  7  Specific Domains of Language Skills in Children with ASD 57B  Morpho-Syntax. Of the studies that have looked specifically at the morphoU  U  syntactic development of this population, there have been variable result which is not surprising, given the variability with which individuals in the spectrum present. TagerFlusberg (1981) found that some syntactic abilities were preserved in this population and later on found that some subgroups of children with ASD had syntactic development that resembled that of children with Specific Language Impairment (Roberts, Rice, & TagerFlusberg, 2004). This conclulsion is corroborated by Bartolucci and colleagues (1980) and Howlin (1984) who found that children with ASD tend to omit certain morphemes, including articles, auxiliary, and copula verbs and tense markings, when compared to both typically developing children and children with mental impairments. Some have found that children with ASD also have particular trouble with pronoun reversals (Fay, 1969), though others have suggested this challenge is in part attributed to echolalia (Paul et al., 2007). Echolalia, the repetition of words or phrases, is a common language characteristic of children with ASD and is thought to serve a communicative purpose, for example, as a means for responding when one has a limited ability to respond appropriately (Paul et al., 2007). In summary, it seems as though children with ASD are capable of acquiring morpho-syntactic abilities, but struggle with some particular concepts. Phonology. One area of language development that seems to be a relative U  U  strength amongst children with ASD is that of speech sound development (Paul et al., 2007). Prosody, however, has been found to be unusual in this population with  8  descriptions including odd vocal quality, inappropriate intonation, and stress patterns (Rutter, Mawhood & Howlin, 1992). Language Use. Use of language seems to be, by far, the most difficult area for U  U  children with ASD. Preschool aged children rarely use language for comments, showing off, acknowledging the listener, initiating social interaction, or requesting information, though they may respond appropriately in highly structured situations (Landry & Loveland, 1989; Wetherby & Prutting, 1984). In general, these children seem to have deficits in the social, rather than the regulatory uses of language (Wetherby, 1986). Several other studies have looked at the narrative abilities of children with ASD, finding that these children had particular trouble with central coherence in story telling (Diehl, Bennetto & Young, 2006; Loveland & Tunali, 1993; Norbury & Bishop, 2003). There seems to be a common finding that use of language and social pragmatics is a common challenge for children with ASD. Lexical Development in ASD 32BU  One aspect of language that has not been extensively studied in children with ASD is that of lexical development. A few studies have taken an in-depth look at the progression of how children begin acquiring words. This is surprising given that the number of hours of SLP service between the ages of two and three—a period that is ordinarily dominated by vocabulary learning—predicted positive language outcomes (Turner, Stone, Pozdol, & Conrad, 2006). There is a clear need for SLPs to have a more extensive knowledge of vocabulary development to provide better service for children with ASD.  9  Trends in the Study of Lexical Development in ASD 58B  Receptive vs. Expressive Vocabulary. A longitudinal study by Charman and U  U  colleagues (2003) was interested in looking at the particular discrepancy between understanding meaning of words and expressing words in very young children with ASD. They found, through administering MCDI- Words and Gestures parent report forms, that word production exceeded that of word comprehension in this population. This is an interesting trend given that typical children tend to show greater receptive vocabularies before they are able to start expressing words. However, the comprehension scale on the MCDI parent-report checklist has been found to be less reliable in comparison to its value as an expressive language measure (Tomasello & Mervis, 1994). Another study assessed 120 older children ranging in age from 5;6 to 19;7 (Jarrold, Boucher & Russell, 1997) and found conflicting results. The researchers administered standardized language tests (British Picture Vocabulary Scale, Test of Reception of Grammar, Action Picture Test, Word Finding Test & Coloured Progressive Matrices), looking at receptive and expressive language skills. They found that the generative use of expressive language was not superior to language comprehension— trends that parallel the progression of how typically developing children learn language, comprehension occurring prior to production. They did, however, find that children with ASD had slightly better performances when expressing single words than when asked to comprehend single words. Lexical Composition. Of the studies that have looked at vocabulary development in U  U  children with ASD, some have noticed this population’s preference for acquiring nouns ahead of other parts of speech. A study by Williams (1993) looked at the vocabulary  10  development of a boy diagnosed with autism from the ages of 2;6 until he reached 3;9, a time when his vocabulary size was around 250 words. Through the use of parent reports, the researcher found that the majority of the words being used by the boy at this time included nouns. Interestingly enough, the second most frequent class of words in his vocabulary included modifiers and not action words (Williams, 1993). Despite these interesting findings, little work has looked at how verbs, describing words, and other vocabulary items develop in children with ASD. Tager-Flusberg and colleagues (1990) compared children diagnosed with autism in contrast to children with Down Syndrome, with each group ranging in age from 3;3 to 6;9 at the start of the study. Groups were matched on chronological age and language level through MLU scores. These researchers collected language samples bi-monthly over a period of 12 to 26 months. Language samples that were a minimum of 100 utterances were transcribed, entered into SALT and analyzed in terms of MLU, IPSyn, lexical diversity, and form class distribution. In terms of vocabulary, they found that both children with ASD and Down syndrome had a dominance of nouns in their transcripts. They did, however, notice trends in their use of nouns in relation to other aspects of language development. They found that as MLU increased, the proportion of nouns used decreased in both groups. At the same time, they found that verbs and function words increased as language became more advanced—a trend that is similar to the literature found in typically developing children. A more recent study (Parisse, 1999) found some similarities in proportion of nouns when comparing transcribed language sample data of children with ASD, Down Syndrome, SLI, and normal development (all matched on MLU scores) interacting with a  11  parent. Parisse (1999) found that children with ASD had a large number of nouns in their language sample transcripts, but this was a common characteristic across all of the comparison groups. Parisse was particularly interested in looking at the influence of parent speech on the language output of these groups. Interestingly enough, the children with ASD were the group that adhered most closely to the linguistic output of parents. Parisse speculated that this may have been due to deficits in semantics and a difficulty for children with ASD to be flexible enough to build classifications and link knowledge from multiple sources. Lexical Meanings. Other studies have looked further into the possibility of a deficit U  U  in lexical meanings in children with ASD, including ambiguous terms and relational meanings. Menyuk and Quill (1985), in their book discussing early communication patterns in autism, postulated that children with ASD had significant challenges with relational terms including verbs, prepositions, and adjectives given their difficulty with shifting perspective. They acknowledged, however, that there have been no studies that have looked exclusively at verb acquisition in this population (Menyuk & Quill, 1985). More recently, Norbury (2005) was interested in looking at the ability of older children ranging from 9 to 17 years of age to decipher meaning between ambiguous lexical nouns (e.g. “bank” as a place to store money and “bank” as a river bank) both in a single word-picture matching task and in a sentence context. Norbury compared children with language impairment, children with ASD and language impairment, children with ASD and normal scores on standardized language measures, and typically developing children. Groups were matched for non-verbal intelligence. Norbury found that all children knew both meanings of the ambiguous word, but children with language  12  impairment and children with ASD and language impairment had more errors on the less familiar meanings of the ambiguous word than both typically developing children and children with ASD and no language impairment. This suggests that for some children with ASD, there may be a specific language component that makes it difficult to process some areas of lexical semantics. The study focused on the meaning of ambiguous nouns, but suggested further research is needed in lexical semantics in children with ASD, looking at individual differences in language skill and verb processing in particular (Norbury, 2005). Summary. The area of lexical development in children with ASD has been difficult U  U  to study, different studies have had conflicting results for a variety of reasons. One of the primary difficulties of studying the acquisition of vocabulary in this population is the wide variability among this population. As can be seen from the aforementioned studies, children with the ASD diagnosis can present as highly verbal, with normal scores on standardized language tests, to below age range in all aspects of language. The problem with several of these research studies is that they compare small subgroups of children with ASD, many of whom fall into the “high functioning” category as they are the ones who can perform on standardized language tests that are used for many research studies. Studies that exclude children with limited verbal abilities or who are unable to perform on such tests may have results that do not give a complete picture of all children in the spectrum. There is a need for more rigorous research comparing individual differences across the entire spectrum of the disorder, particularly addressing the progression of how children with ASD compare to typical language learners in terms of acquiring words.  13  Furthermore, there are few studies that have looked at lexical development using longitudinal data with young children and as such there is not enough knowledge to say whether the process of word acquisition in ASD is delayed, disordered, or comparable to children with typical development. The current study aims to address these issues by comparing lexical development in ASD to typically developing (TD) groups using longitudinal data that spans over four years. Typical Vocabulary Development 3BU  The literature on vocabulary is rich and diverse. If we focus especially on the early stages, when single word utterances predominate, we find three lines of research that could provide insight into the language development of children with ASD: (1) developmental changes in the proportion of different types of words, (2) the predictive value of specific word types for later language achievement, and (3) the order of acquisition of words other than nouns. Each one of these will be discussed briefly in the sections below. Proportion of Words 59B  This is one area of vocabulary development that has been studied extensively over the years. The one class of words that children generally start to acquire is that of nominals. An early diary study by Nelson (1973) looked at first 50 words in young children’s vocabulary and found that two thirds (65%) of these words were made up of both common and proper nouns. The remaining third included describing or demanding action words (14%); modifiers (9%); personal-social words such as “please”, “yes”, “no” (8%); and function words (4%).  14  A detailed look at the how the proportion of word types progresses as typical children develop is provided by Bates and colleagues (1988). These researchers studied 27 typical children longitudinally at the ages of 13, 20 and 28 months. Data were collected twice, once in the home and once in a laboratory and both sessions involved using a mixture of parental interviews and observations of free play. The researchers found that on average, typical children at 13 months say about 12 words whereas by the age of 20 months they say an average of 142. At the age of 28 months, children produced roughly the same number of words in sessions as they did at 20 months of age, but had developed a sudden spurt in their grammatical development—combining words and lengthening utterances. In terms of the actual composition of these vocabularies, Bates and colleagues (1988) also found some interesting trends. They found that children progress from acquiring a greater proportion of nouns at the age of 13 months to expanding to all open class words (i.e. nouns, verbs, adjectives), particularly verbs, at the age of 20 months. At the age of 20 months, 46.8% of total words were made up of nouns, verbs made up 8.3% and adjectives made up 7.5%. At the age of 28 months, the proportion of nouns to total words decreased to 31.6%, while verbs increased to 15.6% and adjectives made up 5.5%. Bates and colleagues noted the importance of the increase in verbs at this age, given that they coincide with a spurt in grammatical complexity. Given these trends, it seems that typical children begin to use nouns and then expand to use a variety of words, with predicate words (such as verbs and modifiers) coinciding with a large vocabulary spurt. Also, as predicate words begin to be used more often in children’s vocabularies, there seems to be a related decrease in the proportion of nouns being used.  15  Predictive Value of Word Types 60B  Another aspect of vocabulary development that has been studied is how early vocabulary growth is related to later growth in other areas of language development. Bates and Goodman (1999) found strong correlations between a vocabulary spurt at 20 months of age and later MLU scores at 28 months of age, suggesting that early grammar is dependent on vocabulary size in typically developing children.  These researchers  proposed a link between the emergence of lexical predicates 1 (particularly verbs) and the F  F  transition from single to multiword speech (Bates & Goodman, 1999). This suggests that predicates, rather than nouns, are particularly important in vocabulary development and could potentially become the foundation upon which later grammatical structures are built. Pinker (1989) proposed a similar idea, finding that predicates, specifically verbs, have particular properties that influence and direct learning of grammar. Bates and colleagues (1988) particularly identified verbs and other closed class morphology as essential for the expansion of sentence structure because of their ability to express relational information. Predicates, primarily led by verbs, express relationships to other words and seem to be the foundational elements upon which later sentence structure is built. Predicate Typology and Order of Acquisition of Predicates 61B  Aside from predicates being important lexical elements for grammatical development, they have clear importance in conveying relational meanings in sentences. Two influential research teams have argued further that certain relational meanings are  1  Lexical predicate: Words that encode the logical predicate; may be members of virtually any syntactic class (Johnston, ASHA 1986) 16  expressed earlier than others. One way by Lois Bloom and her associates (1970), and the other way by Gordon Wells and a group of researchers in Bristol (1985). Of these, Wells’ analysis scheme is the more detailed. He found that children generally start off with unstructured utterances that involve calls for attention or requests. How children proceed to convey subsequent meanings is complex and Wells has noted some patterns that children typically begin to follow. In terms of experiential meanings, children typically acquire wanting predicates before all others. They also acquire physical and perceptual states that are unchanging (e.g., see, hear, etc) before they acquire the affective experiential states (e.g., hate, love, etc). Children tend to acquire these unchanging states before expressing that agents cause change in the physical or cognitive states. Wells also found that children typically are able to comment about communicative events (e.g., read, say, show) before they are able to express how agents or events can cause change in physical, cognitive, or affective states (e.g., listen, think). Similarly, in terms of function meanings, Wells found that the first categories to emerge are that of agent function, patient function, and agent function on a patient. Agents causing patients to function seems to emerge somewhat later as these are meanings that involve embedded clauses. In terms of location and possession, he noticed that children tend to express locative relations before possessive relations. He also noted that children express relational meanings of agents causing change in existential or physical states and locative (e.g., build, clean, cook) or possessive states (e.g., give, share, take) before they are able to express quantitative predicates (e.g., big, each, empty).  17  In terms of expressing meanings of time, Wells noted that temporal predicates (e.g., yesterday, tonight) are generally one of the last meanings that children learn to express appropriately (Wells, 1974). Goals of the Present Study 14B  The goal of the present study is to take a more in depth look at lexical acquisition in children with ASD, focusing on predicates and using longitudinal observations. The study compared data from children with ASD to trends seen in typically developing children from normative assessment measures and/or reported in the literature in the following areas: 1) Developmental change in the composition of the lexicon, as indexed by the proportion of nouns to predicates. 2) The value of predicate use for predicting later grammatical development as indexed by both diversity and number. 3) The order of acquisition of predicate types. Few researchers have explored lexical development in children with ASD but as mentioned above, some researchers (Tager-Flusberg et al., 2003; Williams, 1993) have found some interesting similarities between these children and those with typical development. Given this, the current study hypothesized that children with ASD will have similar lexical development patterns as typically developing groups in each of the above listed areas.  18  CHAPTER TWO: METHODS 5B  Overview 15B  The main purpose of this study was to provide an extensive look at vocabulary development in children with ASD. To do so, it looked at: 1) the composition of vocabulary and how it changes over time in relation to typically developing children; 2) predicate use as it predicts later grammatical development; and 3) the order of emergence of specific predicate types. This chapter presents the two sets of data involved in this study—children with ASD and their typically developing peers—and the measures used to analyze each of these groups. The bulk of this chapter focuses on how data were analyzed in both of the groups for each of the three research questions. Participants 16B  This study analyzed data from two subject pools—children with ASD and their typically developing peers. Data collection methods for each of these groups will be presented below. Typically Developing Group 34BU  All data used to analyze language development in the typical developing (TD) group was accessed from the CDI CLEX (Cross-Linguistic Lexical Norms) Online Database. This database includes month by month norms from 16 to 30 months of age on the typical word production and word comprehension of young children learning English. All norms in the database are from scores on the MacArthur Bates Communicative Developmental Inventories (MCDI). These norms were generated from a norming study conducted by Dale and Fenson (1996) involving 1,130 children whose parents completed 19  MCDI forms. This current study made use of a variety of different time points from the CDI-CLEX database, depending on need for answering specific research questions. These time points will be specifically defined in relevance to each question in the upcoming sections. ASD Group 35BU  The ASD data for this study was accessed from an archived database established by the Autism and Developmental Disabilities (ADD) Laboratory at the University of British Columbia. This database was gathered for a project examining early intervention outcomes for children with ASD and their parents in British Columbia, Canada. Seventy children participated in this project and were seen for language, cognitive and social assessments on an annual basis from 2001 to 2006. The study that is presented in this paper is part of a larger set of studies analyzing language relevant data from this ASD database. Selection Criteria for ASD Group 62B  The current study included those children from the larger study who had English as their primary language spoken in the home and who were also reported to be “verbal” at a minimum of two time points in the archived database. Verbal children were operationally defined as those with an expressive vocabulary of at least 30 words as indexed by scores on either the MacArthur-Bates Communicative Developmental Inventories-Words and Sentences (MCDI-WS) or Words and Gestures (MCDI-WG) forms.  20  Organization of ASD Longitudinal Data 63B  After participants had been selected using the criteria described above, the data were organized to reflect developmental patterns. Before testing vocabulary hypotheses, the subjects were equated on a pertinent general developmental variable to ensure that they were at the same stage of language development. As age has been found not to be the most useful measure when dealing with longitudinal vocabulary data (Smolik, 2004), this study used total vocabulary size as the measure by which to organize the data developmentally. For analysis purposes, the first time point (T1) was redefined as the point in the larger study at which each subject met the inclusion criteria for the present study. The succeeding three time points were of data that was collected annually after they reached this initial level. In other words, the second time point in the current data (T2) was data collected one year after T1, the third time point (T3) was two years after T1, and the fourth time point (T4) was three years after T1. Organizing the data by vocabulary size, rather than by age or date, removed non-verbal children from the group, facilitated comparisons with the TD group, and was more appropriate for the current research questions. These developmentally organized time points were used for all analyses involving the ASD data. ASD Data Specifics 64B  Data at T1 2 consisted of 49 children (7 females, 42 males) whose parents had F  F  completed either the MacArthur-Bates Communicative Developmental InventoriesWords and Sentences form (MCDI-WS) or Words and Gestures form (MCDI-WG). 12 2  All data time points (i.e. T1, T2, T3, T4) referenced in the text refer to the developmentally organized time points based on vocabulary size and not the data collection time points used in the original archived database. 21  of these 49 had received treatment to meet the inclusion criteria. At T2, the sample size remained constant at 49 children, while at T3 it dropped down to 37 and at T4 it dropped even further to 20. Further detail on subjects’ mean age, non-verbal IQ, autism severity, and vocabulary size are provided in the table below. Table 2.1 ASD Group Specifics at T1 91BU  Mean of Group  SD  Range of Scores  Age in Months  52.84  11.22  28 – 75 (2;4-6;3)  Non-Verbal IQ  48.98  16.57  38 - 101  CARS-Autism Rating  34.62  5.89  21 - 46.5  Total Vocabulary Size  222.24  195.19  32 - 663  U  U  U  U  U  U  Measures 17B  The primary data for this investigation came from a standardized measure of language development—the MCDI—that was administered to each child at each of the data points. Some additional measures, including an autism severity rating (Childhood Autism Rating Scale) and a cognitive early learning assessment (MULLEN Scales of Early Learning) were also administered. MacArthur-Bates Communicative Development Inventories (MCDI) 36BU  The MCDI are parent report forms primarily composed of word checklists aimed to establish a child’s vocabulary inventory. All vocabulary data from both ASD and TD groups used in this study comes from these parent report forms. The MCDI forms provided a detailed look at the composition of each child’s vocabulary. There are two 22  different types of MCDI forms that were used in this study—WG and WS—and each of these are described below. MCDI-Words and Sentences (WS) 65B  The MCDI-WS vocabulary checklist is organized into several categories including animals, animal sounds, vehicles, toys, food and drink, clothing, body parts, small household items, furniture and rooms, outside things, places to go, people, games and routines, action words, descriptive words, words about time, pronouns, question words, propositions and locations, quantifiers and articles and connecting words. It includes a total of 680 words. It also includes a second section on the child’s ability to use sentences and grammar, including checklists of word endings, irregular word forms, and sentence patterns. MCDI-Words and Gestures (WG) 6B  The MCDI-WG has the same categories as the MCDI-WS form, but with fewer words in each of the categories as it is geared towards younger children. The total number of words on the MCDI-WG is 396, about 60% of the total words on the MCDIWS. The MCDI-WG form does not have a section on sentences and grammatical development, but rather focuses on early communicative skills including sections for parents to note a child’s use and understanding of gestures and other early communicative and play skills. Data from both forms were used for the group comparisons in the present study.  23  Rationale for the MCDI 67B  The MCDI was a valuable measure in this study as it provided a valid and reliable basis for vocabulary comparisons between the ASD population and those with typical development. This parent report form has been found to be a valid measure of vocabulary development in typical populations (Fenson et al., 1993), particularly for when examining expressive, rather than receptive vocabulary (Tomasello & Mervis, 1994). It has also been found to be particularly useful in research with children with ASD (Condouris & Tager-Flusberg, 2003) given the unique behavioral, motivational and attentional issues that often interfere with standardized testing. Childhood Autism Rating Scale (CARS) 37BU  The Childhood Autism Rating Scale (Schopler, Reichler, DeVellis, & Daly, 1980) is a rating scale originally designed to help diagnose children with ASD from other developmental delays. It includes a 15 item rating scale wherein a child is rated on a scale of 1 to 4 (with 1 being a level of low severity and 4 being a level of higher severity). The 15 items include: 1) relating to people, 2) imitation, 3) emotional response; 4) body use; 5) object use; 6) adaptation to change; 7) visual response; 8) listening response; 9) taste, smell, and touch response and use; 10) fear or nervousness; 11) verbal communication; 12) nonverbal communication; 13) activity level; 14) level and consistency of intellectual response; and 15) general impressions. This scale has been found to be reliable and valid (Schopler et al., 1988) and has been found to be superior to other measures such as the Autism Behaviour Checklist (Eaves & Milner, 1993). Further information on how this measure was used in the current study is presented below. 24  Mullen Scales of Early Learning 38BU  The Mullen Scales of Early Learning (Mullen, 1995) is a normed measure of both non-verbal and verbal cognitive abilities for infants and children up to the age of 68 months. It includes five scales: gross motor, fine motor, visual reception, expressive language, and receptive language. This measure allows researchers to calculate T-scores, percentile ranks, and age equivalent scores for each of the scales. It has also been used by past researchers for children diagnosed with ASD (Anderson et al., 2007; Lord, Risi & Pickles, 2004). Further information on the relevance of this test to the current study is presented below. Data Preparation 18B  This study aimed to create an extensive profile of early vocabulary growth in children with ASD by focusing on three areas of lexical development—proportion of nouns to predicates, predictive value of lexical predicates for later grammatical development, and the order of acquisition of predicate types. The Proportion of Nouns to Predicates 39BU  As one index of the changing composition of the child’s vocabulary, data from the MCDI was used to calculate the proportion of predicates and nominals in the overall list of words the child was reported to have spoken. This was completed for both the ASD and TD groups.  25  TD Group 68B  Longitudinal time points. To look at how the composition of vocabulary in U  U  typically developing children compares with the ASD group, this study used data from three time points in the CDI-CLEX Database. These three time points were selected because the mean total vocabulary size at these points matched the total vocabulary means for T1, T2, and T3 in the ASD group (see Table 2.2). Table 2.2 ASD and TD Groups Matched on Mean Total Vocabulary Size 92BU  ASD Grp at T1  TD Grp at 21 Mos.  ASD Grp At T2  TD Grp at 29 Mos.  ASD Grp at T3  TD Grp at 30 Mos.  Mean Total Vocab Size  222  208  431  433  518  519  SD  195  157  192  174  185  125  Coding. All words on the MCDI forms were coded as either a “nominal”, U  U  “predicate”, or “other”. Nominals included all words in the animals, vehicles, toys, food and drink, clothing, body parts, small household items, furniture and rooms, outside things, places to go, and people categories. Predicates included all words from the action words and descriptive words categories. Predicates also included some words from the words about time, quantifiers and articles, prepositions and locations, helping verbs, and question words categories. Predicates were classified as such on the basis of their potential to convey a logical predicate meaning in a sentence and their grammatical function mostly as verbs, adjectives, and prepositions. All other words on the MCDI form that were not coded as predicates or nominals were considered as “other” and these mostly included animal sounds, social words for games and routines, some articles and  26  connecting words (e.g. “an”, “the”, “but”). Please refer to Appendix A for a list of all words and their codes. Analysis. Once coding was completed for all words on the MCDI forms, norms U  U  for the number of words coded as predicates or nominals were generated from subjects in the three matched time points in the CDI-CLEX online database. The total number of spoken words, total number of nominals, and total number of predicates were ascertained for each of the selected age groups (i.e., 21, 29, and 30 months). Proportion of nominals and predicates was then calculated as a function of total vocabulary size. ASD Group 69B  Longitudinal time points. To look at how the composition of vocabulary changes U  U  in children with ASD, this study looked at the MCDI scores from the ASD group at three of the developmentally organized time points—T1, T2, and T3. Coding. Each word reported as spoken on a child’s MCDI form was coded as a U  U  predicate, nominal, or “other” as described above (see Appendix A). Analysis. Following coding, the researchers calculated the proportion of U  U  nominals and predicates reported as spoken by each child as a function of the total number of words spoken as reported in their MCDI form. Reliability checks for these calculations was completed on 25% of the subjects. Reliability for this proportion of the sample was at 95%. Once these individual proportions were deemed as reliable, group proportions were then calculated and compared with the mean values of the typically developing groups.  27  Comparative Analysis of ASD and TD Groups 70B  Figures were generated to descriptively compare the mean proportion of predicates and nominals in both of these groups and their trends over time. It was not possible to determine whether groups significantly differed from each other using statistical analyses since there was no way to calculate variance in the TD data. Further analysis was possible, however, for the ASD group data. Given this, a repeated measures one-way ANOVA was conducted in order to examine trends in the proportion of predicates and nouns over the three time points in the ASD group. Predictive Value of Predicates for Later Grammatical Development 40BU  Prior research indicates a statistical link between the emergence of lexical predicates (particularly verbs) and the transition from single to multiword speech, suggesting that these words are significant in the emergence of multi-word combinations (Bates & Goodman, 1999). Given this, the present study was interested in determining whether or not such links exist in children with ASD. ASD Groups and Predicate Value 71B  Regression analyses were conducted to determine whether predicate use was linked to grammatical development in this population. The predictive strength of other factors that may play a role in language learning was also tested. Total vocabulary size, number of predicates, number of nominals, autism severity ratings, age, and non-verbal IQ were all considered as potential variables that may play a role in later grammatical development. All data for the independent variables were accessed from T1 of the ASD data set. Definition for these factors were as follows:  28  Total vocabulary size. This variable was defined as the total number of words U  U  that a parent reported as spoken on either the MCDI-WS or WG forms. Total number of predicates and nominals. These variables were defined as the U  U  total number of predicates (or nominals) that a parent reported as spoken on either the MCDI-WS or WG forms. Predicates/nominals were defined and identified as above (see Appendix A). Total number of predicates/nominals was used rather than percentages of predicates/nominals because the percentage computation yields different proportions as is expected given the variation of vocabulary size in the sample. Total number of predicates/nominals was thought to give a more accurate description of use of predicates/nominals. Autism severity. This variable was defined as the child’s total score on the U  U  Childhood Autism Rating Scale. Age. This variable was defined as the child’s chronological age in months at the U  U  time that their parents completed the MCDI-WS or WG forms. Non-verbal IQ. This variable was defined as a child’s visual reception and fine U  U  motor t-scores on the Mullen Scales of Early Learning. These tests have been used as “non-verbal” measures in previous research studies (Anderson et al., 2007). Dependent Variable 72B  Later syntactic development was the dependent variable of study for determining the predictive value of predicates. Syntactic development was defined as the average MLLU (mean length of longest utterance) from parent’s report of their child’s longest three utterances. This score was generated from Section D in the Sentences and Grammar portion of the MCDI-WS form, which requires parents to write down the three 29  longest sentences that they have recently heard their child say. MLU for each sentence was calculated using the guidelines described in the 2007 MCDI manual (Fenson et al., 2007). These guidelines are based on Brown’s system for computing MLU, but have particular rules on how to compute MLLU. Once MLU was scored for each sentence, the mean MLU for all three sentences was obtained and this was the score used to define each child’s syntactic development. There was a large variability in length of utterance some ranging from short and very simple utterances such as “I want cookie” (MLU=3) to long and very complex utterances such as “Blade sorcerer is my imaginary friend who is also magical and has a lot of cool powers that can capture bad guys.” (MLU=23). All data on MLLU was accessed from MCDI-WS forms at T2 (one year after collection of the predictive variables). Analysis 73B  A correlational analysis was conducted to determine if grammatical development at T2 correlated with each of the described independent variables at T1. Once these correlations were conducted, a further multiple regression analysis examined the links between all independent variables that were found to correlate with grammatical development at T2. Order of Acquisition of Predicate Types 41BU  The order of acquisition for relational meanings was investigated by examining groups of predicates defined by meaning type. This was completed in both ASD and TD groups to determine whether or not there are differences between the groups in the order of acquisition for major meaning types.  30  TD Group 74B  Longitudinal time points. To look at how predicate types emerge in typically U  U  developing children compared with the ASD group, this study used data from 15 time points—16 to 30 months—from the CDI CLEX Database. Predicate words at each of these time points were further analyzed. Coding. All words from the MCDI list that had been coded as predicates (see U  U  Appendix A and the discussion above) were further grouped by meaning type (Wells, 1983). Each predicate was coded using a version of the Predicate Coding System (PCS), a categorized lexicon that included 700 surface predicates found in the speech of children 0-5 years of age. The PCS was originally developed by the Berkeley Cross-Linguistic Project (Antinucci et al., 1973; Wells, 1985) and was supplemented with information from the general literature on child language by Johnston (2001). The words in the PCS belong to different syntactic classes such as verbs, adjectives, prepositions, adverbs or conjunctions but all express judgments about states and relationships. The present study used a 16 predicate category coding system, a version of the PCS that had been developed by Johnston and colleagues for clinical use (Johnston, Miller & Tallal, 2001). These codes represented the consensus view of 12/16 linguists and graduate students of linguistics. Approximately 2/3 of the predicates on the MCDI were listed in the original PCS and assignment of these words to meaning type categories was maintained from the original scheme. The remainder of the predicates were assigned by the current researchers in an analogous fashion. The 16 predicate categories were as follows: (1) Modals-notions of possibility, necessity and intentionality; (2) Experiential States-physical and perceptual; (3)  31  Experiential States-affective and cognitive; (4) Changes in cognitive, perceptual or physical experience; (5) Agents or events causing changes in affective, cognitive, perceptual or physical experiences; (6) Communicative events (a subset of type 5); (7) Activities-movements and actions of agents or objects without concern for resultant endstates; (8) Agents causing activity in other objects or agents; (9) States-physical, categorical, dispositional, existential, locative; (10) States-quantitative; (11) Changes in States (9 and 10 above); (12) Agents causing changes in state-existential, physical or quantitative; (13) Agents causing change in state-locative or possessive; (14) SelfMovement (arguably a subset of Type 13); (15) Temporal; and (16) Negatives. Each predicate on the MCDI was coded into one of these categories of meaning. After all predicates had been coded into a category, it was found that no predicates existed for Category 4, only one existed for Category 8, and none of the words in category 16 were present on both of the MCDI-WG and WS forms. Given this, these categories were not used for further data analysis. It was also found that Category 9 included a very large number of predicates and this category was split into two—(9P) States-physical, categorical, existential, dispositional and (9L) States-locative—for further analysis. Please refer to Appendix B for a list of all predicate words used for analysis and their respective meaning types. Analysis. Using this coding system, norms from the CDI CLEX database were U  U  generated for words belonging to each predicate type discussed above. All words in each category were inputted into the database website which created tables of the norms for those words. It specifically generated the average number of words reported as spoken in each predicate category for each month between the ages of 16 to 30 months. A “general  32  occurrence” criteria was set such that at least three words from a given meaning category were required to be reported as spoken by children at a given age in order to conclude that that meaning category was being generally expressed. (This criteria was lowered to two words for predicate type 6—communicative event predicates—as there were only four members of that class; all other classes had at least six members.) Once each predicate type was established as being expressed or not at each time point, researchers were able to look at order of emergence by seeing which predicate types occurred at earlier ages and which emerged at later ages. This order of emergence was then compared with the ASD group. ASD Group 75B  Longitudinal time points. To look at the order in which predicates emerge in U  U  children with ASD, this study looked at the MCDI word checklists from the ASD group at T1, T2, T3, and T4. Coding. All predicates on the MCDI forms were coded using the version of the U  U  PCS described above (see Appendix B). The words that each child was reported to use at T1, 2, 3, and 4 were noted and grouped by meaning type. A customized computer program was written to assign words to categories as described above, but prior to this categorization it was necessary to enter each item checked off for each child’s MCDI form. Reliability checks of this data entry task were completed on 25% of the sample and indicated 95% accuracy. Analysis. Following this assignment of predicates to a meaning type, each child’s U  U  MCDI data at each of the time points was used to determine the order of emergence of the different meaning types. “General Occurrence” of a meaning category again required 33  the presence of at least three members of the class (two members in the case of category 6). This allowed the researchers establish an overall level of acquisition for each of the meaning types that would include children who had smaller vocabulary sizes. Note that in addition to indicating some level of general use for the spectrum of subjects, this decision rule allowed the researchers to use data from both the MCDI-WG and WS forms. Once the predicate types that occurred in each child’s MCDI data had been identified, a further criteria was set to determine whether or not a predicate type had been “acquired” by the ASD group. All predicate types that met the occurrence criteria for at least 60% of the subjects in the sample were considered as acquired. Order of emergence was then established by noting which categories of meaning had been generally used by at least 60% of the ASD children at a given time point. Comparative Analysis of ASD and TD Groups 76B  Figures were generated to descriptively compare the order of predicate type emergence in each of the groups; this was aided by Guttman Scale Analysis of the ASD data. Summary 19B  This chapter focused on the main coding and analysis procedures that were used to answer the research questions posed in the previous chapter. It has described how these steps were completed for both the data from children with ASD and children with typical development. The next chapter will focus on the results and comparative analyses that were completed between both groups.  34  CHAPTER THREE: RESULTS 6B  Overview 20B  This study provides a detailed look at lexical development in children with ASD using normative data from the MCDI parent report vocabulary measure. The previous two chapters described the rationale and methodological procedures that were conducted in order to answer the three specific research questions posed in this paper: (1) Does the composition of the lexicon—in terms of the proportion of nouns and predicates—differ in children with ASD as compared with a typically developing group at a similar level of language development?; (2) Does use of lexical predicates predict later grammatical development in children with ASD?; and, (3) Do children with ASD acquire different types of predicates in the same order as typically developing children?. This chapter will present results from data analyses that were designed to answer each of these research questions. Question 1: The Proportion of Nouns to Predicates 21B  To look at how vocabulary development might differ in typically developing children and children with ASD, this study first examined the composition of each group’s lexicon by comparing the proportion of nouns and predicates at three longitudinal points for each of these populations. TD and ASD Group Comparisons 42BU  Data from the MCDI were used to calculate the proportion of predicates, nominals and “other” words in the overall list of words each subject was reported to have  35  spoken. Only the proportions of predicates and nominals were analyzed since they have been the focus of other child language research. Comparison of Mean Proportions 7B  As described in Chapter 2, groups were matched on total vocabulary size prior to comparing proportions of nouns and predicates between the two groups. Total vocabulary size at T1, T2, and T3 in the ASD groups was compared to three age groups in the TD database that best matched each of the ASD time points on total vocabulary size. Group means for each time point are presented in Table 3.1 and Figure 3.1 below. Table 3.1 Average Proportion of Predicates and Nominals Reported as Spoken in ASD 93BU  and TD Groups 94BU  T1 U  U  U  T2 U  U  T3 U  TD21 mos.  ASDT1  TD29 mos.  ASDT1+12mo  TD30mo  ASDT1+24mo  Nominals  63.42%  61.16%  56.79%  58.34%  56.39%  56.99%  Predicates  23.76%  22.29%  31.79%  29.99%  32.48%  30.48%  208  220  433  431  519  518  Total Vocab  36  Figure 3.1 Average Proportion of Predicates and Nominals in ASD and TD Groups Over 102BU  Time 70.00% Use of PredicatesASD Child Time  60.00% 50.00%  Use of NominalsASD Child Time  40.00% 30.00%  Use of PredicatesTD  20.00%  Use of Nominal-TD  10.00% 0.00% Time 1  Time 2  Time 3  Matched Time/Age Groups (Matched on Vocab Size)  As can be seen, the proportion of predicates and of nominals is virtually identical at each time point for the ASD and TD groups when total vocabulary size is equated. Both ASD and TD groups showed trends wherein the proportion of nouns decreased with time and the proportion of predicates increased with time, although not dramatically. Group differences are clearly evident, however, when passage of time and actual age are taken into account. A second graph was generated in order to capture the age and time interval differences between data collection points in each of these groups. From T1 to T3, the ASD and TD groups achieved the same growth in proportion of predicates and nouns, but at T1 the age difference between the two groups was 31 months (ASD Mean CA = 53mo, TD Mean CA = 21 mo) while at Time 3 the age difference was 44 months (ASD Mean CA = 74 mo, TD Mean CA = 30 mo). These figures indicate not only a significant delay in lexical development by children in the ASD group, but a rate of  37  learning that appears to be slowing over time instead of showing the rapid acceleration seen in the TD data. During this phase of development, the TD children are initially reported to be learning roughly 30 words/month but increase to a rate of some 80 words/month. The children in the ASD group, in contrast, move from a reported rate of 20 words/month to a rate of less than 7 words/month (see Figure 3.2). More rigorous statistical tests of group differences were not possible given the unavailability of individual scores from the typically developing group, but there seems little doubt that while the general composition of their lexicon may be normal, the ASD group showed evidence of serious delays and difficulties with this learning task. Figure 3.2 Vocabulary Size Growth in ASD and TD Groups Over Time 103BU  600 500 400 ASD TD  300 200 100  24  20  16  12  8  4  T1  0  Months Past Time I  ASD Analysis. Two repeated measures one-way ANOVAs were completed in U  U  order to look at trends in the growth of predicates and nouns over time for the ASD group. Significant differences were found for the proportion of nominals F(2, 72) = 5.93, p = 0.004 and the proportion of predicates F(2, 72) = 35.66, p = 0.00. Post hoc Tukey 38  tests revealed significance differences between the proportion of predicates when comparing T1 with both T2 and T3 using p < 0.01. No significant differences were found for the proportion of predicates between T2 and T3. Similarly, significant differences were found for the proportion of nominals when comparing T1 with both T2 and T3 using p < 0.05. No significant differences were found for the proportion of nominals between T2 and T3. Post hoc Analyses 43BU  Split Groups Another aspect of interest was the wide range of variability present in the range of ASD scores (see Table 1). Recall that T1 was defined as the first test point at which a child’s total vocabulary exceeded a minimum of 30 words. At this time point, vocabulary size in the ASD group ranged from 32 to 663 with a mean of 222 and a SD of 195. Given such variability, there was the potential to split the group for further analysis. The ASD group was split into three different groups—low group, mid group, and high group—based on the total number of words reported as spoken on the MCDI forms at T1. The low group had under 75 total words reported as spoken, the mid group had 75 to 250 total words reported as spoken and the high group had over 250 words reported as spoken. Group averages on the proportions of nouns and predicates were computed and results are available in Table 3.2.  39  Table 3.2 Proportions of Nominals and Predicates in Low, Mid and High Vocabulary 95BU  ASD Groups Low Vocab Group U  U  Mid Vocab Group U  U  U  High Vocab Group U  T1  T2  T3  T1  T2  T3  T1  T2  T3  Nominals  57.40  60.23  58.65  68.34  59.22  57.67  59.74  55.82  54.42  Predicates  16.92  26.20  29.32  19.15  30.01  31.92  29.92  33.75  33.87  The low group (N=18) was of particular interest given that these subjects were potentially comparable to earlier TD groups (See Table 2). The low group had a very different total vocabulary size from the matched TD group used in the initial analysis of predicates and nominals. Given this, a younger comparison TD group was selected for the “low” ASD children at T1 to determine whether the low group followed a pattern reflecting earlier development. Groups were re-matched on total vocabulary size as reported on the MCDI. The three TD groups that closely matched the 3 low group time points were 16 months, 22 months and 28 months. Please see Table 3.3 for matched group specifics. Table 3.3 Low ASD Group and TD Groups Matched on Mean Total Vocabulary Size 96BU  Matched Group 1  Mean Total Vocab Size  Matched Group 2  Matched Group 3  Low Grp at T1  TD Grp At 16 Mos.  Low Grp At T2  TD Grp at 22 Mos.  Low Grp At T3  TD Grp at 28 Mos.  46  59  285  257  425  414  Once groups were matched, proportions of nominals and predicates were generated for the new age TD groups. The average proportion of nominals reported as 40  spoken by this new TD group was 62.67% at 16 months, 61.53% at 22 months, and 58.88% at 30 months. The average proportion of predicates reported as spoken was 14.68% at 16 months, 26.34% at 22 months, and 30.19% at 28 months. These results were plotted in Figure 3.3 along with the average proportions for the low vocabulary ASD group. The low ASD group does follow a pattern seen in earlier normal development. As can be seen there is a high level of agreement between groups. Figure 3.3 Proportions of Nominals and Predicates in Low ASD Group and Re-Matched 104B  TD Groups  Percentage of Words in Lexicon  70.00%  Use of Predicates-ASD Low Grp  60.00% 50.00%  Use of Nominals-ASD Low Grp  40.00% 30.00%  Use of Predicates-TD matched to Low  20.00% 10.00% 0.00% Time 1  Time 2  Time 3  Use of Nominal-TD matched to Low  Question 2 : The Predictive Value of Early Predicates for Syntactical Development 2B  To determine whether predicates in the lexicon have any connection to later grammatical development in children with ASD, several correlational and regression analyses were performed. Comparable TD group data was unavailable in the CDI CLEX Database and as such, only ASD group data were used in these analyses. 41  Correlational Analysis 4B  Correlation analyses were completed between age, non-verbal IQ, autism severity, total vocabulary size, total nominals, and total predicates to determine if a relationship existed between these variables and syntactic development at a later age. Significant correlations were found to exist between later grammatical development at T2 as indexed by MLLU and the following variables at T1: non-verbal IQ, total vocabulary size, total number of nominals, and 4) total number of predicates. No significant correlations were found between chronological age or autism severity (CARS) at T1. Table 3.4 presents a list of all Pearson’s r values. Table 3.4 Correlation Coefficients between Independent Variables at T1 and Syntax 97B  Development at T2 r(40), p < .05  MLLU at T2  Independent Variables at T1  Age  NonVerbal IQ  Autism Severity  0.13  0.43*  -0.29  Total Vocab Size 0.65*  Total Nominals  Total Predicates  0.63*  0.70*  Multiple Regression Analysis 45B  A multiple regression analysis was conducted to further analyze whether predicates, as opposed to other correlating variables, predicted later grammatical development. The multiple regression included all factors that were found to correlate with grammatical development at T2; namely, non-verbal IQ, total vocabulary size, total number of predicates, and total number of nominals. This linear regression F(4, 38) =  42  9.37, p < .05 revealed that, once the variance attributable to number of predicates (b = 0.96, p = .03) was removed, there were no further significant predictors of later grammatical development. Question 3 : The Order of Emergence of Lexical Predicates 23B  The order of acquisition for categories of predicate meanings was investigated by looking at groups of predicates defined by meaning type. This was completed in both ASD and TD groups using a set coding and criteria system designed to identify the order of meaning type emergence in each of the groups. TD Group 46B  Using norms available through the CDI CLEX database, this study looked at the order of emergence for categories of spoken predicates in typically developing children from 16 to 30 months of age. Criteria and coding systems, including assignment of a predicate to a category based on the PCS and calculating each predicate category’s “occurrence” based on the presence of at least three members of a given class (see details in previous chapter), were applied to the group data provided in the database. Predicate types and the ages at which they emerged are presented below in Table 3.5.  43  Table 3.5 Age of Emergence of Spoken Predicate Types in Typically Developing 98B  Children Age in Months  Predicate Type  17  7  Activity Predicates  19  3  Experiential States: Affective and Cognitive  9P  Physical States  9L  Locative States  10  Quantitative States  12  Agents or Objects Causing Change in Physical States  13  Agents or Objects Causing Change in Locative  21  Predicate Type Description  States  23  14  Self-Movement Predicates  2  Physical and Perceptual States  5  Agents or Events Causing Change in Experiential States  26  30  15  Temporal Predicates  6  Communicative Event Predicates  11  Changes in Physical States  1  Modals  44  ASD Group 47B  Predicate types at each of the four time points from the ASD Data were analyzed using the coding and criteria systems described in the previous chapter. At T1, the ASD group had only acquired two predicate types-7 (Activity Predicates) and 9L (Locative States). By Time 2, however, they had acquired all predicate types except for Type 1 (Modals). They only acquired Type 1 predicates by Time 4. This is shown in Figure 3.4 below. Figure 3.4 Development of Predicate Types in ASD Group at 4 Time Points 105B  Time 1  Time 2  Time 3  Time 4  106B  Type Type Type Type Type Type Type Type Type Type Type Type Type Type  1 2 3 5 6 7 9L 9P 10 11 12 13 14 15  45  This analysis did not reveal any significant order of emergence because in between T1 and T2, this group had acquired all but one of the predicate types. Further analysis was conducted to look at specific predicate type order. Post Hoc Analysis of ASD Data 78B  Given that all predicate types had been acquired by T2 in the ASD group, further analysis solely focused on T1 of this population. To determine the order of emergence, all predicate types meeting the criteria of the presence of at least three members of its class were further sorted into an order. The order was established on the basis of total number of children meeting the occurrence criteria. For instance, if a predicate type had more subjects meeting the occurrence criteria than did another predicate type, it was considered to be an earlier emerging predicate type. This sorting system allowed the study to determine an order of predicate type emergence at T1. Please refer to Figure 3.5 for the order of acquisition based on total number of subjects meeting predicate acquisition criteria.  46  Figure 3.5 Order of Predicates Types Based on Total Number of Predicates Acquired 107B  108B  45  Type Type Type Type Type Type Type Type Type Type Type Type Type Type  40 35 30 25 20 15 10 5 0  7 9L 9P 3 10 12 14 5 13 15 2 11 6 1  1 Predicate Type  Once this order was established, a Guttman Scale Analysis (Guttman, 1950; Levelt, Schiller, & Levelt, 2000; Sandhofer & Smith, 1999) was used to determine whether the order of development implicit in these grouped data did in fact capture the subject-wise order of emergence for this set of meaning types. Several orders compatible with Figure 3.5 were evaluated. The order of development that showed the highest degree of predictive strength was one in which categories 9L-9P, categories 3-10, categories 12-13, categories 15-2 and categories 11-1 were treated as unordered sets (i.e., that emerged in a predictable order between but not within sets), but otherwise was the same as portrayed in Figure 3.5 demarked by vertical black lines. The order of each of these sets was determined through looking at the individual variability of scores. The Guttman Scale allowed examination of the points at which individual scores became more stable and 47  these are the points at which sets were determined. The coefficient of reproducibility for this scale was .94, indicating that it was highly likely that if a child was expressing three meaning types, it would be the first three categories listed. Likewise, if a child was expressing four meaning types it would be type 7, 9L, 9P plus one other from the next set and so forth through the whole system. This scale thus seems to approximate the underlying order of acquisition of meaning types for the ASD group. Please refer to Appendix 3 for details of the final Guttman Scale. This analysis was also repeated removing children who had received therapy at T1 (12 children). The order of acquisition and coefficient of reproducibility did not change. Comparative Analysis 48B  After establishing order of emergence for predicate types for the ASD group at T1 and for the TD group, the study compared the orders in both groups. A Spearman rank order correlation coefficient was computed to determine the degree of similarity shared in the order of emergence of predicate categories between these two groups. Predicate category emergence rank order was found to be highly correlated in both TD and ASD groups given a Spearman rank correlation coefficient value of rs = .96 with p < .05. Despite the strong similarities, the orders had some slight differences between them. Further inspection of the ordered categories indicated that three meaning types were responsible for the small degree of difference that existed—these were predicate categories 3 (cognitive and affective states), 5 (agents or events causing change in experiential states), and 10 (quantitative predicates). Predicate category 3 emerges “later” in the ASD group. In the TD group, category 3 came in with category 9, but in the ASD group, it came in after category 9—thus making it “delayed” in children with 48  ASD. Predicate category 5 emerges “earlier” in the ASD group. In the TD group, category 5 comes in after categories 12, 13, and 14; but in the ASD group, it comes in along with these three categories. Similarly, category 10 also seems to emerge “earlier” in the ASD group. In the ASD group, category 10 comes in before categories 12, 13, 14, but in TD comes in with these three categories. When predicate emergence order for the two groups were compared excluding these exceptional categories (i.e. categories 3, 5, and 10), the orders of acquisition for major meaning types in the two groups were virtually identical as can be seen in Table 3.6. Table 3.6 Order of Emergence of Predicate Types in TD and ASD Groups 9B  Predicate Type Emergence Order  ASD  TD  I  7  7  II  9L, 9P  9L, 9P  III  12, 13, 14  12, 13, 14  IV  2, 15  2, 15  V  11, 6  6, 11  VI  1  1  Post Hoc Analyses Comparing Specific Early Emerging Word Types in Both Groups 79B  Further analysis was completed to look into the potential differences between ASD and TD groups in terms of specific words for each of the predicate categories. Researchers compared early emerging words in each of the predicate categories for both 49  groups. For the TD group, a word belonging to a predicate category was considered early emerging if it was one of the first three words from the predicate category that were being spoken by at least 60% of the subjects. For the ASD group, only subjects who had 1 to 3 words present in the predicate category were considered as “early emerging” candidates. Once these subjects were identified, their individual words were analyzed and the three words that were expressed by the most number of “early emerging candidates” were considered as “early emerging words”. Upon completing this task, it was discovered that majority of the subjects had over 3 words for categories 7, 9L, and 9P and as such could not be considered as “early emerging” any longer. The opposite was true for Category 1, wherein only majority of the subjects had not yet acquired any of these words. Given this, these four categories (1, 7, 9L, and 9P) were excluded from this early emerging word analysis. Both ASD and TD lists of these early emerging words from each predicate category is available in Table 3.7 below. This comparison showed strong agreement with the early words being expressed for children in both groups for all of the predicate categories. Table 3.7 TD and ASD Early Emerging Words from Predicate Categories 10B  Predicate Type 2  ASD  TD  See  See  Sleepy  Hungry  Tired, Hungry, Sick, Thirsty 3 F  F  Asleep  3  All of words separated by a comma in this table had an equal number of responses from the early emerging candidates 50  Table 3.7 TD and ASD Early Emerging Words from Predicate Categories 3  5  6  10  11  12  13  Yucky  Yucky  Happy  Happy  Good  Love  Look  Look  Tickle  Tickle  Touch  Hurt  Read  Read  Say  Hide  Hide  Show  Allgone  Allgone  More  More  Big  Big  Fall  Fall  Out  Out  Find  Find, Say  Open  Open  Wash  Wash  Close, Clean  Break  Splash  Hold  Throw  Slide  Wipe, Slide  Throw  51  Table 3.7 TD and ASD Early Emerging Words from Predicate Categories 90B  14  15  Go  Go  Push  Ride  Pull  Hit  Fast  Fast  Finish  Wait  Wait  Now  Summary 24B  This chapter presented the results obtained from the statistical analyses, both planned and post hoc, that were conducted to answer each of the three research questions. The main results of this study focused on three aspects of vocabulary development in children with ASD—general composition of vocabulary, predictive value of predicates, and order of emergence of predicate types. It was found that TD and ASD groups had comparable percentage of predicates/nominals when matched on vocabulary size, but children with ASD acquired their vocabulary later and at a notably slower rate. Predicates were also found to be significant predictors of later syntactic development in children with ASD. Finally, order of emergence of various predicates types were found to be comparable in both ASD and TD groups with a high level of similarity in the examples of early learned words. The upcoming chapter will discuss the implications of these statistical analyses and provide significant connections between previous research and the findings of this current study.  52  CHAPTER 4: DISCUSSION 7B  Overview 25B  The studies looking at specific trends in early vocabulary acquisition in children with ASD have been few and far between. Though it is characteristic of these children to have delays in communicative abilities, some researchers have found that there is some relative preservation of the formal aspects of language in these children. Tager-Flusberg (1981) was a pioneer in suggesting that children with ASD had relative preservation of their formal aspects of language such as phonology, syntax, morphology, with deficits in the area of pragmatics and semantics. More recently, a study that sampled 89 children and administered a variety of standardized language measures found that, among the verbal children diagnosed with ASD (about a quarter of their sample), basic form and content of word knowledge were comparable to mental age; but higher order semantic skills, with special attention to the use of mental and affective mental states, was particularly challenging (Kjelgaard & Tager-Flusberg, 2001). Furthermore, one longitudinal study that compared the development of vocabulary and syntax in six children with ASD, found that only one tended to follow an atypical pathway of development in terms of lexical composition and growth of MLU (Tager-Flusberg et al., 1990). These findings are not widely acknowledged, however, and the more common view is that children diagnosed with ASD have primary deficits in their ability to communicate (Paul et al., 2007), causing them to learn words very slowly and to not combine words until their later preschool years (LeCouteur et al., 1989). The main goal of this study was to contribute to the resolution of these conflicting claims by further comparing early vocabulary development of children diagnosed with 53  ASD to that of children with typical development. It did so by comparing data from TD groups to ASD groups and examining three trends in lexical development: change in the composition of the lexicon, the predictive value of predicates, and the order of emergence of meaning types. Unlike previous studies looking at language in ASD, this study was unique in the fact that it had a relatively large sample including 49 subjects with varying levels of verbal ability, and made use of longitudinal data over a span of four years. In this final chapter, the main objective will be to state the significance of the research findings of the study and what each of these findings tell us about the lexical development in young children with ASD. It will begin with a summary of the research findings presented in the previous chapter. Following this, each research question will be addressed by presenting how each answer informs us about lexical development and what this adds to the knowledge of ASD. The chapter will end by presenting implications these findings have both for future research studies in this field as well as for clinicians working with this population. Discussion of Research Findings 26B  Three aspects of lexical development were selected for comparison between ASD and TD groups: (1) the change in lexical composition over time; (2) the predictive value of lexical predicates; and (3) the order in which major relational and stative meanings emerge over time. Each of these will be considered in turn in the following sections of this paper.  54  Question 1: Change in Lexical Composition (Proportion of Nouns and Predicates) 49B  Similarities in ASD and TD Groups 80B  Ratio of Lexical Composition Over Time. The main goal for this question was to determine whether or not ASD and TD groups differ in the composition of their lexicon as indicated by the proportion of nouns to predicates and changes in this ratio over time. Children in the TD and ASD groups were matched on total vocabulary size at three time points and were found to have similar proportions of nouns and predicates at each of the three time points. These longitudinal findings indicate that not only are ASD and TD groups similar in the ratio of nouns to predicates at a single point in lexical acquisition but both share a common trend in the way this ratio changes and develops over a period of time. Differences between ASD and TD Groups 81B  Despite these significant similarities between these groups, there are also some key differences in the ASD and TD data. When looking at demographics at T1 for both the ASD and TD groups, the average age for each was widely divergent. Children with ASD had an average age of 53 months at T1, while children in the TD group were all 21 months of age at T1—a difference of 32 months. These findings suggest a significant delay in lexical acquisition. Delay in Rate of Vocabulary Learning. This delay could be due to a slower rate of word learning and the longitudinal data of this study allow us to determine whether or not such is the case. Comparing the results, the TD group acquired new words initially at a rate of 20 words per month, but this quickly accelerated to a rate of some 80 words per month over the span of 9 months. The children with ASD, on the other hand, started off 55  at a rate of 26 words per month, but instead of increasing, this rate drops to 8 words per month over the span of 2 years. This decrease in rate of learning was evidenced for the ASD group not only in terms of vocabulary size, but also in the proportion of predicates and nouns. Post hoc analyses compared proportions of nouns and predicates of children with ASD at T1, T2, and T3. Results from a one-way ANOVA indicated that the proportion of nouns and predicates significantly differed from each other when comparing T1 to T2, but not between T2 and T3. In other words, the proportions for children with ASD developed significantly within a year, but this rate of learning seemed to slow down after this point. It was not possible to determine whether similar trends occur in TD groups since we did not have data for individual children given the nature of the data available through the CDI-CLEX database for typical lexical norms. The accelerated rate of learning implicit in the three ages chosen as comparison points do seem to suggest that there is an increase, rather than a decrease in the three TD age groups rate of learning. This is particularly evident when recalling that it initially took the TD group a span of 8 months (vs. one year for the ASD group) and then 1 month (vs. another full year for the ASD group) to achieve what it took the ASD group 2 years to achieve. Delay in Onset of Lexical Development. It seems likely that a delay in lexical development reflects both a late onset of word learning as well as a slower rate of growth in acquiring expressive words. The strongest evidence pointing in this direction comes from T1 data. Post hoc analysis of the data suggested that both late onset and slow rate of learning contribute to this delay. T1 was defined as the first point at which a child had at least 30 words listed in the expressive section of the MCDI. The variance in  56  vocabulary size at this point was quite high in this initial group (SD=195), so further analysis was conducted focusing on 19 children who had 75 words or less at T1. The children in this “low” group were on average 50 months of age. Comparatively, children in the TD group who had 30 to 75 words were an average of 16 months of age. This vast age difference clearly suggests a delay in vocabulary acquisition for children with ASD. However, this low group also argues a case that this delay is due to a later onset of word learning. Children typically develop their first words at some point during the ages of 10 to 16 months (Fenson et al., 1994), usually around the time of their first birthday. Assuming children with ASD also begin learning words at this point in their development (the age of 12 months), then it would mean it takes them close to 40 months to reach under 75 words, an incredibly slow rate of 1.24 words a month. Given that they are not necessarily learning that slowly, it argues the case that vocabulary delay in at least some subgroups of children with ASD is partly due to later onset of vocabulary development. Comparison to Relevant Literature 82B  Proportions of Nominals Dominate Over Predicates. Although few prior studies exist, the findings from this study are compatible with other reports on the different lexical classes found in young children. Two of these studies considered the vocabulary composition of children with ASD. The first was a case study of a young boy with ASD that found comparable results when examining the content of his emerging lexicon—that is, nouns were the most frequent class of words in his vocabulary of approximately 250 words (Williams, 1993). A second study comparing children with ASD to children with Down Syndrome found again that nouns were the most common lexical class in the speech of both these developmentally delayed populations (Tager-Flusberg et al., 1990). 57  Studies of other atypical groups, such as “late talkers” found that between the ages of 2 and 3, 61% of their lexicon were nouns (Rescorla, Alley & Christine, 2001). The fact that nouns seem to dominate across a variety of special populations suggests that these trends reflect a general pattern in the language learning process. Research on typical early lexical development have similarly found that a majority of the early words spoken by young children are nouns; with nouns dominating over predicate words by comprising over 60% of the lexicon (Nelson, 1973; Fenson et al., 1993; Rescorla et al., 2001). Child language theorists have explained that children learn nouns early on because nouns are object-reference terms and as such they are easily mapped to the perceptual-conceptual world (Gentner, 1982). Gentner, after looking at cross-linguistic studies and patterns of language teaching, came to the conclusion that nouns, as object concepts, are readily available in the child’s world and as such are easily learned one at a time. Predicates, as action-relational concepts, must first be discovered by the child before he/she can begin to match such concepts with words. The fact that the current study found a dominance of nouns in children with ASD—a population characterized as having language and communication deficits—adds support for the notion that nouns have a more transparent semantic mapping in comparison to predicates. Change in Ratio of Predicates to Nominals Over Time. As this was a longitudinal study, it allowed examination of the proportions of nouns and predicates in both TD and ASD groups over time. In both groups, over the span of 3 years, the proportions of nouns, while consistently dominating over the proportion of predicates, slowly decreased as the amount of predicates increased. These results echo previous findings from TagerFlusberg and her colleagues (1990) who found—when looking at the longitudinal  58  language development of six children with autism—that proportion of verbs and function words increased as language became more advanced. This is also a trend found in typical language development (Bates et al., 1988). This is significant when taking into account that even children with ASD—who are considerably challenged learners—have to contend with predicates because of their essential role in organizing language and propositional expression. Considering the hypothetical case of not increasing their proportion of predicates is untenable because children with ASD would not be able to express meanings or expand their language beyond labeling and we find this is not the case. Delay in Onset of Lexical Development. Few studies have been able to explore the early stages of lexical acquisition in children with ASD. One case study of a young boy with ASD followed his speech and language capabilities from the time he was 2;8 up until he was 4;5 (Williams, 1993). At his initial assessment, this child was already considered delayed in his expressive language because his linguistic skills were tested using the Griffiths Scale of Mental Development and found to be at the 1 year old level, already indicating a delay of 20 months. This suggests that even very early on, the delay in language learning is in part due to a later onset of this process. Williams’ study is one of the few that have been able to document the very early progression of vocabulary acquisition in this population. That being said, it lacks strength in its conclusions given that it is only a case study of one child with ASD. However, taking Williams’ findings together with that of the current study which included a larger sample size, supports the theory that language delay in ASD is due to a later onset of vocabulary acquisition.  59  Delay in Rate of Vocabulary Learning. This study found that the rate at which children with ASD learn words seems to slow after reaching a particular level. Few studies have examined the rates of vocabulary acquisition in children with ASD. Reviews of the literature in children with autism have made general statements and observations that the rate of language learning is slow (Paul et al., 2007). Researchers have also explained that findings regarding language delays and rates of learning in this population have been variable, given the diversity with which this disorder presents (Roberts, Rice, & Tager-Flusberg, 2004). One study looked at vocabulary acquisition in five children with ASD using growth trajectories over a period of 3 years and found that vocabulary learning was indeed variable and dependent on early pragmatic skills including joint attention and communicative intent (Rollins, 1999). One of the children had a fast and steady rate of learning words, another a slower and steady rate, one had a relatively flat rate with a later vocabulary spurt, while the other two had relatively flat learning curves. Given that Rollins’ study (1999) included only five children, it is difficult to make any assumptions regarding vocabulary learning rates for these children. The current study, however, with its larger sample size, allows for stronger argument that there is a decrease in the number of words being acquired by children with ASD in comparison to TD groups who have a steady increase in vocabulary size. Summary 83B  While children with ASD have some clear delays in their ability to acquire vocabulary, they share some key similarities with TD groups in this language learning process. The current study, given its large sample size, strengthens Tager-Flusberg and colleagues’ conclusion that children with ASD may have more similarities in the 60  development of their early lexical composition to TD groups despite their characteristic deficits in communication. Question 2: Predictive Value of Predicates 50B  Research Findings 84B  The goal for this research question was to determine whether or not predicate words in the lexicon of young children with ASD were predictors of later syntactical abilities. This was selected as a goal based on previous research with TD children which has found that lexical predicates are associated with later multiword combinations in language development (Bates & Goodman, 1999). This current study was focused on determining if a similar relationship existed for young children with ASD as well. The results indicated that total number of predicates were a significant predictor of later syntactical development as indexed by a child’s MLLU score. Though other factors, including non-verbal IQ, total vocabulary size, and total number of nominals, were also found to be significantly correlated to later development of multiword speech, total number of predicates was the only factor that remained a predictor when all these related variables were factored in. These results add support to the growing literature on the unique value of predicates in connection with development of multiword utterances. Comparison to Previous Literature 85B  The findings from the current study found similarities between ASD groups and the literature on TD language development in the significance of predicate words to later length of multiword speech (a common measurement of syntactical and grammatical abilities). Though this current study lacked a control group to measure this process in TD  61  populations, the rich literature on early language development in typical populations can be used as a means of comparison. Research in TD groups has long found a significant connection between vocabulary size and advancing grammatical development (Bates & Goodman, 1999). Child language theorists have long speculated that it is specifically the increasing number of verbs and closed class parts of speech that contribute to an increase in MLU and more advanced language abilities (Bates et al., 1988). The current study supports this theory finding that vocabulary size does indeed have a connection to later multiword combinations, but it specifically found that the acquisition of predicates has a particular significance to these later syntactical abilities. Only one previous study has examined this relationship in children with ASD. Tager-Flusberg (1990), examined longitudinally the language abilities of six children with ASD and found that the proportion of nouns in the speech of all the children decreased as their MLU increased. This decrease in the proportion of nouns naturally coincided with an increase in the number of verbs and closed class parts of speech. Tager-Flusberg, however, did not specifically look at the correlation between these verbs and later MLU. The current study takes this correlation one step further by factoring out other related variables and found that it was predicates alone that remained as a significant predictor of later grammatical development. Taking both the current study’s findings with that of Tager-Flusberg (1990), adds support to Pinker’s (1989) theory that verbs and predicate words have a unique role in the building of more complex speech and grammar in both TD and language-delayed children. Additionally, both findings together, support the idea that the development of  62  early language abilities of children with ASD follows a more similar pathway to TD than might be expected. Question 3: The Order of Emergence of Predicate Types 51B  Research Findings 86B  The third goal for this research question was to determine whether or not TD and ASD groups followed similar patterns in terms of their order of emergence of predicate types. Both TD and ASD groups were analyzed using comparable methods in order to determine the order in which these types were acquired. The results indicated that several aspects of the emergence order were strikingly similar between both the ASD and TD groups, though the ASD group was delayed in its acquisition of certain predicate types. Order of Emergence of Predicate Types in TD Groups. Given that vocabulary growth was rapid; that observations, while frequent, were not continuous; and that only grouped data were available, it was not possible to determine the order of acquisition for each of the individual meaning types. The data did indicate a reliable order of acquisition for six sets of predicate types, although an order of acquisition for the types within each set could not be determined. Results indicated that the first set of predicates to be acquired was that of activity type predicates (e.g., cry, dance, hug). These were then followed by cognitive/affective experiential states (e.g., love, bad), physical states (e.g., cold, dirty) and locative states (e.g., up, in). The next group of predicates included that of quantitative states (e.g., more, big), causal and self-movement (e.g., bring, go), and agent/object causing a change in physical state (e.g., cut, wipe). The fourth set of predicates to emerge included 63  physical/perceptual experiential states (e.g., sleepy, tired), agent/object causing a change in experience (e.g., pretend, touch) and temporal states (e.g., wait, before). The penultimate set of predicates to emerge included the communicative event predicates (e.g., show, read) and predicates involving potentially non-agentive changes in state (e.g., find, stay). The last of all predicate types to emerge was that of modals (e.g., can, gotta). Order of Emergence of Predicate Types in ASD Groups. Similarly, the order of emergence of predicate types in ASD groups was also more reliable when considered in sets rather than as individual meaning types. In the case of the ASD children, the interval between observation points proved a bit long, even for slow learners. This meant that more than one new meaning type was likely to be listed at each successive observation point, and there was no way to determine which of the new arrivals had been learned first. Strikingly enough, with the exception of three meaning categories, the order of emergence of the sets was the same. The three meaning types which were different were predicate categories 3, 5, and 10. Meaning type 3 includes cognitive and affective states, and was found to come in later in children with ASD. In the MCDI, however, the majority of the terms refer to affective states. Words such as yucky, happy, and good were the words most likely to appear in the data for these children. The next exception is category 5 which is changes in experiential states (including physical, affective and cognitive states) and was found to come in “earlier” in the ASD group. Typical examples in this category were look, tickle, and touch. Interestingly enough, think, listen , and pretend—the terms from category 5 which are considerably related to theory of mind—were the more rare samples found in the ASD data. The third exceptional category was that of category 10 which includes  64  quantitative predicates. This category was also found to be somewhat “early” in children with ASD. Frequent examples of words from this category included more and big. Comparison to Previous Literature 87B  Order of Emergence of Predicate Types in TD Groups. The literature on how children begin to use predicate terminology to convey meanings is rich and complex. It is significant to mention that, given the nature of the data used in the current research study (i.e., word checklists), it was not possible to capture the manner in which a child used the actual word, only whether or not the word was reported to be spoken by the child. Given this, it is difficult to determine exact relational meanings that the child might have been using a word to mean which limits any direct comparison between the current data or the previous literature on emergence of predicate meaning types. Despite this, it was possible to find common elements between the findings from the TD populations in the current study in comparison to ones before it. Previous literature by Wells (1985) has emphasized that unchanging states, including physical and affective predicate types, emerge before those that include some change or an agent causing change in a particular state. These findings were replicated in the current study, with activity, physical and locative state predicate types emerging before those that involved change in state (i.e., inchoatives) or agents causing changes state (i.e., causals). There were, however, several differences in findings. Wells (1985) found that predicates involving an agent causing change were more likely to emerge before quantitative predicates. This however, was not the case in the current study, wherein quantitative and changing predicates were found to emerge at approximately the same time period. This could largely be due to the fact that certain words in the MCDI 65  checklist that were coded as quantitative terms including “more” and “big”, tend to emerge very early on and drive the category to be defined as “acquired”. Wells in contrast may have coded such terms, particularly “more”, in a class of very early predicates that involves meanings of requests, wants, and needs rather than any other significant meaning. Wells (1985) also found that children typically are able to comment about communicative events (e.g., read, say, show) before they are able to express how agents or events can cause change in physical, cognitive or affective states (e.g., clap, play, jump). These findings were also not replicated in the current study, which found that communicative event predicates were actually one of the later sets of predicates to emerge even in TD groups. A final difference between the TD data of the current study and Wells’ order of emergence involved the physical/perceptual states and the cognitive/affective states. Wells found that physical and perceptual predicate meanings typically emerged before cognitive and affective meanings. From the TD groups in the present study, it was found that such was not the case. Looking more closely at the words in the cognitive and affective category, the majority of them are more affective attributes including yucky, good, and love which would explain the early emergence of this meaning type category in the current data. Though not all the findings from the current study’s TD groups replicated the findings from previous literature on the acquisition of relational meaning, the results from the current study remain useful as a comparison for the ASD group. Order of Emergence of Predicate Types in ASD Groups. Few studies have been conducted looking at the early lexicon of children with ASD, and none specifically have examined the emergence of specific predicate types, despite the fact that predicates are  66  uniquely linked to the development of later multiword speech. Knowing that current research in children with ASD has more recently found more similarities than differences in their language development even at the preschool level (Tager-Flusberg, Paul, & Lord, 2005), it is not surprising that the current study also found the order of emergence for predicate words to be comparable in both TD and ASD groups. The current study did, however, find some interesting exceptions in the ASD group when comparison to the TD group in their order acquiring certain predicate types—particularly with regards to cognitive/affective predicates (Type 3), quantitative predicates (Type 10), and predicates involving changes in experiential states including physical, affective and cognitive states (Type 5). Type 3 predicates included those that involve cognitive and affective meanings and were found to come in later in children with ASD than those in the TD group. Majority of the terms in this category included affective attributes such as good, love, yucky. This is not all that surprising considering that previous research has found that children with ASD have struggled with words involving affect. Kjelgaard and TagerFlusberg (2001), in a study looking at the language profiles of 89 ASD children administered a variety of standardized language tests, also found similar results reporting that more abstract semantic skills, particularly the use of affective and mental state words were more challenging for children with ASD. Furthermore, delay in these more social and affective predicate types is not surprising given the social interaction deficits that are characteristic for this population. Category 10 included predicates that involved quantitative meanings and these were found to come in early in ASD as compared to the TD group. The most frequent  67  words in this category included “more” and “big” in both the TD and ASD groups. These quantitative states coming in ahead in the ASD group could be a reflection of advanced age and cognitive capabilities given that they were 2 years older and have had more experiences and exposure to these concepts. Meaning category 5 included those predicates involving changes in experiential states (including physical, affective, and cognitive states) and this was also found to come in earlier in the ASD group in comparison to the TD group. This is not all that surprising considering it could again be related to the fact that these words reflect an area where we might expect to see a 4 year old acting differently than a 2 year old. This category also includes some higher cognitive skill words such as think, listen, pretend, and some might be surprised to find that these such cognitive state terms are “early” in this population given their characteristic deficits in Theory of Mind tasks even at a young age (BaronCohen, 1993). Further examination of the most frequent examples of this meaning category from children with ASD included look, tickle, and touch. None of these are cognitive state terms and have to do with more physical and sensory issues which are common across children with ASD. In fact children with ASD have been found to frequently have sensation seeking behaviors (Myles et al., 2004), which could potentially explain the commonality of “tickle” in this meaning type. It is worth mentioning that these exceptionalities in the order of acquisition of predicate type could very well simply be caused by limitations in the data set. For instance these are a reflection of the early stages of vocabulary learning and the meaning type categories are large. Furthermore, close to a quarter of these children had received some form of early intervention and results could be a reflection of treatment affects.  68  Despite this, however, these interesting findings provide remarkable insight into the early world of children with ASD. Summary of Findings 52B  In general, this study found that children with ASD follow similar patterns of lexical development as TD children, albeit with delays and exceptions in certain areas and with an overall slower rate of learning. A more detailed summary of the findings is presented in Table 4.1 below. The following sections will present a more detailed look at how these findings significantly add to our growing knowledge of ASD. Table 4.1 Summary of Research Findings 10B  Question 1:  Question 2:  Question 3:  Change in Lexical Composition  Predictive Value of Predicates  Order of Predicate Emergence  Proportion of nouns and predicates in ASD did not differ from TD when groups matched on vocabulary size.  Significant correlations between non-verbal IQ, total vocabulary size, total nouns, total predicates and MLLU 1 year later  TD and ASD did not differ on order of emergence of major predicate types, except for: - type 3: delayed in ASD - type 5: early in ASD - type 10: early in ASD  TD learned up to 80 words/month while ASD learned words much later and at a rate of 26 words/month  Only total predicates predicted MLLU 1 year later when others factors were controlled  TD and ASD did not differ in specific words learned within each category of meaning  Relevance of Findings to Theory: What Do We Now Know About ASD? 27B  Knowing now that the early lexicon of children with ASD follows similar, albeit delayed, patterns of development to TD groups in regards to each of the abovementioned aspects of lexical development, it is the goal of this paper to understand what such 69  information adds to the understanding of autism. There seems to be an emerging trend of finding some relative preservation of language abilities in ASD when comparing this population with mental-age-matched peers (Kjelgaard & Tager-Flusberg, 2001). This knowledge instigates more questions than answers: Why is it that children with ASD are capable of acquiring words and tend to learn similar word classes as typically developing children, but are still unable to be successful in more functional aspects of language and communication? Furthermore, why is this acquisition of words so severely delayed in this group? To attempt to answer these questions, there is a need to look through the literature on typical language and communication development. Clearly, there is something happening in typically developing children that is not happening in children with ASD. According to Nelson (1996), there are some necessary contributions in order for language to develop into a useful communication system: 1) the biological basis of acquiring a linguistic system; 2) the psychological process that enables the child to construct a particular language system; 3) the social process that both provides and sustains a language system. It is the interaction of each of these contributions that drives the emergence of higher levels of linguistic, social and cognitive functioning that is characteristic in the later part of early childhood (Nelson, 1996). Applying this to the current research findings suggests that children with ASD may have some aspects of these processes intact. Considering that the current findings indicate that children with ASD do tend to follow typical patterns of lexical development in terms of the proportion of words they acquire and even the specific word types they acquire, it is plausible to assume that children with ASD are capable of acquiring the  70  basis of a linguistic system. It also seems reasonable to assume that the majority of children with ASD do also have the psychological process that allows them to construct a language system, given the fact that they are capable of mapping words onto appropriate meanings. Furthermore, previous research studies have also found that children with ASD also use semantic groupings in typical ways to categorize and retrieve words (Boucher, 1988; Tager-Flusberg, 1985)—again suggesting that an underlying psychological process to construct language may be intact. It is worth mentioning however, that ASD includes a broad range of varying communication deficits, and as such, individual children may vary in the degree to which they possess these two abilities in order to build a language system. Though the children included in this study were all verbal at some point during the study, it is significant to note that by equating all the children on a similar developmental level (i.e. the initial point at which they have a minimum of 30 words in their expressive vocabularies), this study included several ASD participants who were very late talkers as well as those who were quite precocious in their lexical development. Having said that, what appears to be the common “missing link” across all children with ASD is the social process that is necessary to provide and sustain a language system. Knowing now that children follow typical lexical development to some degree, why is it that they cannot build on such abilities to have more “normal” use of language? There is a rich history of finding social deficits in this population, with past researchers suggesting that the pragmatic oddities that are characteristic of the speech of children with ASD only increases the more that they speak (Tager-Flusberg et al., 2005). A deficit in the social process necessary to learn and build a useful communication  71  system is not a novel concept in this area of the field. There is a rich literature on the deficits in early social pre-communicative acts in children with ASD—namely their challenges with joint attention, early gestures, imitation abilities—which have been found to be relevant for later language learning abilities (Bono et al., 2004; McDuffie et al., 2005; Smith et al., 2007; Stone & Yoder, 2001). Knowing that children with ASD follow a typical, though delayed, pattern of lexical development leads to the consideration that these social deficits may play a larger role in children’s ability to sustain and functionally use a language system than originally considered. It is these social acts that may be the driving force behind the language acquisition delays/deficits in ASD, rather than an inability to match meanings to words or use word meanings appropriately. Furthermore, another piece of the puzzle that may be missing in children with ASD is that of the interaction that the social, cognitive, and linguistic areas play in fostering a typical communication system. There seems to be a dissociation in the child with ASD to connect social acts to words; a connection so well established in typical children, that it may make children with ASD appear as though their language skills are on a completely divergent path from TD groups. Which leaves us with some final food for thought: Why do researchers insist that it is important to ascertain that these children are more normal than not? Should we be considering these children as exceptional, and how would an answer to such a question play out in one’s everyday work with these children?  72  Implications for Future Research 28B  Replication of Findings from Current Study 53B  Research Design 8B  Given the limited research that exists on the lexical development of young children with ASD, there is a clear need for future studies to further examine these aspects of the very early language development in this population. The researchers acknowledge that this examination was somewhat irregular in its research design and data collection methods, leaving room for future studies to replicate its findings. For instance, comparison groups between TD and ASD populations were not always comparable given that there was no individual subject data available for TD group comparison—thus, limiting data analysis options. Having said that, however, this study accessed a large database including over 1000 typically developing children in order to produce comparable and valid longitudinal lexical norms to which to compare with the ASD groups in the study—a feat that would have not been possible if the researchers had opted to collect their own data for TD groups. Given this, there are no serious concerns in the validity of the current study’s findings, but it does leave room for future studies to replicate its findings. Data Collection Methods 89B  Aside from an irregular research design, this study based most of its findings on a parent report form, which may not have been the most ideal means of measuring a child’s lexical use, particularly for the analysis of lexical predicate emergence. As mentioned  73  before, it was not possible to analyze the accurate use of the predicate words given that access to how the word being used in context was unavailable. As such, identifying the exact semantic relation that the child used the word for was not possible. Acknowledging this, the researchers recommend attempting to replicate these findings, particularly for the research question involving the order of predicate type emergence, using language sample data or data wherein one can easily interpret which semantic relational meaning the child is referring to. Replicating these findings using language sample data would also enable access to a better understanding of the social/pragmatic deficits that may be hindering children with ASD. Having recognized the value of language sample data as rich for further study, it does not discredit the current findings. Parent report data has been used by researchers in the past and is considered an adequate measure of lexical development, particularly for this population wherein testing procedures are not always possible (Charman et al., 2003; Condouris & Tager-Flusberg, 2003). Future Areas of Lexical Research in ASD 54B  Aside from replicating the findings from the current study, there are some recommendations for future studies in this field. This study found some striking resemblances between TD groups and ASD groups in terms of their proportion of predicates and nouns, predictive value of predicates and order of emergence of predicate types. There are other areas of lexical research that could also be explored to help strengthen the argument that more similarities than deviances exist between these two populations. For instance, given the literature on typical development suggesting that children typically acquire a certain amount of nominal terms before they begin to acquire predicate words, one might further analyze the growth curves in terms of proportions of 74  nouns and predicates to determine if this process also exists in children with ASD. Another idea might be to further examine the predictive value of predicates by looking at whether they predict language abilities other than MLU. More research linking and comparing lexical development of children with ASD to TD groups will help further an understanding of why language and communication is delayed in this population. Further research in the social and cognitive areas are also necessary to determine whether developmental dissociations exist between the linguistic and the social development of these individuals. Social deficits seem to be emerging as the driving force behind the communicative delays characteristic of individuals with ASD, and there is a need for future studies to examine and determine which specific aspects of these are relevant in ASD. Aside from this, there needs to be more research in both TD and ASD to better understand how cognition, language, and social development as foundational elements interact and link with each other to create a functional communication system and foster learning. Implications for Clinical Practice 29B  SLPs are the most common treatment providers of children with ASD (Green et al., 2006); yet, many of these professionals do not know how children with ASD learn words. Given this, there is the potential for SLPs to assume that children with ASD— who have characteristic deficits in communication and social interaction—develop their lexicons very differently from typically developing children. This current research investigation has clarified whether or not such assumptions are true. Furthermore, by providing an overview of how the lexicon develops in children with ASD, the findings  75  from this study has given us new insight into how the young child with ASD makes sense of her world and attempts to communicate in it. Knowing now that the lexical development of children with ASD is comparable to that of typical development has important considerations for any professional working with this population. For one thing, these findings validate the use of typical language developmental milestones as a guideline for selecting appropriate intervention goals. Given the specific findings from the current research questions, that might entail building up appropriate proportions of nouns and predicate words in a child’s lexicon and targeting predicates in therapy as stepping-stones for achieving multiword utterances. It is worth mentioning, however, that though these children may eventually achieve the same lexical goals as TD children, it is probable that the manner in which these goals is met is very different. This is the piece of the puzzle that would most likely be of most useful to clinicians working with children with ASD. Given the knowledge that it is the social piece, rather than the language or cognitive piece that is challenging for these individuals, it makes sense for clinicians to attempt to address these in therapy. For instance, one might tend to emphasize social/affective terminology in the lexicon or build on early pre-communicative acts. Aside from this, however, there is an additional piece that children with ASD struggle with—namely how to interact and use their linguistic system in order to communicate on a social level. It is the task, then, of the clinician to determine how to inspire such a process to happen. 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American Journal of Speech-Language Pathology, 15(4), 378388.  93  APPENDIX A MCDI Words and Lexical Class Codes 9B  Nominals Animals alligator animal ant bear bee bird bug bunny butterfly cat chicken cow deer dog donkey duck elephant fish frog giraffe goose hen horse kitty lamb lion monkey moose mouse owl penguin pig pony puppy rooster sheep squirrel teddybear tiger  Predicates Action Words bite blow break bring build bump buy carry catch chase clap clean climb close cook cover cry cut dance draw drink drive drop dry dump eat fall feed find finish fit fix get give go hate have hear  Other Sound Effects and Animal Sounds baa baa choo choo cockadoodledoo grr meow moo ouch quack quack uh oh vroom woof woof yum yum Games and Routines bath breakfast bye call (on phone) dinner give me five! gonna get you! go potty hi hello lunch nap night night no patty cake peekaboo please shh/shush/hush shopping snack so big! thank you 94  MCDI Words and Lexical Class Codes turkey turtle wolf zebra Vehicles airplane bicycle boat bus car firetruck helicopter motorcycle sled stroller tractor train tricycle truck Toys ball balloon bat block book bubbles chalk crayon doll game glue pen pencil play dough present puzzle story toy Food and Drink apple  help hide hit hold hug hurry jump kick kiss knock lick like listen look love make open paint pick play pour pretend pull push put read ride rip run say see shake share show sing sit skate sleep slide smile spill splash stand stay stop sweep  this little piggy turn around yes Words About Time day morning night time Pronouns he her hers him his I it me mine my myself our she that their them these they this those us we you your yourself Question Words what who Preposition and Locations to 95  MCDI Words and Lexical Class Codes applesauce banana beans bread butter cake candy carrots cereal cheerios cheese chicken chocolate coffee coke cookie corn cracker donut drink egg fish food french fries grapes green beans gum hamburger ice ice cream jello jelly juice lollipop meat melon milk muffin noodles nuts orange pancake peanut butter peas pickle pizza  swim swing take talk taste tear think throw tickle touch wait wake walk wash watch wipe wish work write  Quantifiers and Articles  Descriptive Words  but  a an the Helping Verbs am are be did/did ya do does is was were Connecting Words  allgone asleep awake bad better big black blue broken brown careful clean cold cute dark dirty dry empty fast fine first full gentle good 96  MCDI Words and Lexical Class Codes popcorn popsicle potato potato chip pretzel pudding pumpkin raisin salt sandwich sauce soda/pop soup spaghetti strawberry toast tuna vanilla vitamins water yogurt Clothing beads belt bib boots button coat diaper dress gloves hat jacket jeans mittens necklace pajamas pants scarf shirt shoe shorts slipper sneaker  green happy hard heavy high hot hungry hurt last little long loud mad naughty new nice noisy old orange poor pretty quiet red sad scared sick sleepy slow soft sticky stuck thirsty tiny tired wet white windy yellow yucky Words About Time after before later now 97  MCDI Words and Lexical Class Codes snowsuit sock sweater tights underpants zipper  today tomorrow tonight yesterday  Body Parts  how when where which why  ankle arm belly button buttocks/bottom cheek chin ear eye face feet finger hair hand head knee leg lips mouth nose owie/boo boo penis shoulder tooth toe tongue tummy vagina Small Household Items basket blanket bottle box bowl broom brush  Question Words  Prepositions and Locations about above around at away back behind beside by down for here inside/in into next to of off on on top of out over there under up with Quantifiers and Articles all a lot 98  MCDI Words and Lexical Class Codes bucket camera can clock comb cup dish fork garbage glass glasses hammer jar keys knife lamp light medicine money mop nail napkin paper penny picture pillow plant plate purse radio scissors soap spoon tape telephone tissue/Kleenex toothbrush towel trash tray vacuum walker watch  another any each every more much not none other same some too Helping Verbs can could don’t gonna/going to gotta/got to hafta/have to lemme/let me need/need to try/try to wanna/want to will would Connecting Words and because if so then  Furniture and Rooms  99  MCDI Words and Lexical Class Codes basement bathroom bathtub bed bedroom bench chair closet couch crib door drawer dryer garage high chair kitchen living room oven play pen porch potty refrigerator rocking chair room shower sink sofa stairs stove table TV washing machine window Outside Things backyard cloud flag flower garden grass hose ladder lawn mower moon 100  MCDI Words and Lexical Class Codes pool rain rock roof sandbox shovel sidewalk sky slide snow snowman sprinkler star stick stone street sun swing tree water wind Places to Go beach camping church circus country downtown farm gas station home house movie outside park party picnic playground school store woods work yard zoo 101  MCDI Words and Lexical Class Codes People aunt baby babysitter babysitter’s name boy brother child clown cowboy daddy doctor fireman friend girl grandma grandpa lady mailman man mommy nurse child’s own name people person pet’s name police sister teacher uncle  102  APPENDIX B 10B  MCDI Predicate Words and Predicate Category (Meaning Type) Codes Predicate Category  Words  MCDI Classification  1 - Modals  can could gonna / going to gotta / got to hafta / have to will would  Helping Verbs Helping Verbs Helping Verbs Helping Verbs Helping Verbs Helping Verbs Helping Verbs  2 - Physical and Perceptual States  hear see asleep awake hungry sick sleepy thirsty tired  Action Words Action Words Descriptive Words Descriptive Words Descriptive Words Descriptive Words Descriptive Words Descriptive Words Descriptive Words  3 - Experiential States: Affective and Cognitive  hate like love wish bad better cute fine good happy mad naughty nice poor pretty sad scared yucky  Action Words Action Words Action Words Action Words Descriptive Words Descriptive Words Descriptive Words Descriptive Words Descriptive Words Descriptive Words Descriptive Words Descriptive Words Descriptive Words Descriptive Words Descriptive Words Descriptive Words Descriptive Words Descriptive Words 103  MCDI Predicate Words and Predicate Category (Meaning Type) Codes need / need to wanna / want to  Helping Verbs Helping Verbs  5 – Agents or Events Causing Change in Experiential States  listen look pretend taste think tickle touch wake watch hurt  Action Words Action Words Action Words Action Words Action Words Action Words Action Words Action Words Action Words Descriptive Words  6 – Communicative Event Predicates  hide read say show  Action Words Action Words Action Words Action Words  7 – Activity Predicates  bite blow chase clap cry dance drink drive eat help hug hurry jump kiss lick play run shake sing skate sleep smile swim  Action Words Action Words Action Words Action Words Action Words Action Words Action Words Action Words Action Words Action Words Action Words Action Words Action Words Action Words Action Words Action Words Action Words Action Words Action Words Action Words Action Words Action Words Action Words 104  MCDI Predicate Words and Predicate Category (Meaning Type) Codes swing talk walk work careful gentle how  Action Words Action Words Action Words Action Words Descriptive Words Descriptive Words Question Words  9P – Physical States  black blue broken brown clean cold dark dirty dry green hard heavy hot loud noisy orange quiet red soft sticky wet white windy yellow  Descriptive Words Descriptive Words Descriptive Words Descriptive Words Descriptive Words Descriptive Words Descriptive Words Descriptive Words Descriptive Words Descriptive Words Descriptive Words Descriptive Words Descriptive Words Descriptive Words Descriptive Words Descriptive Words Descriptive Words Descriptive Words Descriptive Words Descriptive Words Descriptive Words Descriptive Words Descriptive Words Descriptive Words  9L – Locative States  fit sit stand high stuck above around at behind beside by  Action Words Action Words Descriptive Words Descriptive Words Prepositions and Locations Prepositions and Locations Prepositions and Locations Prepositions and Locations Prepositions and Locations Prepositions and Locations Prepositions and Locations 105  MCDI Predicate Words and Predicate Category (Meaning Type) Codes down here in / inside next to off on on top of over there under up  Prepositions and Locations Prepositions and Locations Prepositions and Locations Prepositions and Locations Prepositions and Locations Prepositions and Locations Prepositions and Locations Prepositions and Locations Prepositions and Locations Prepositions and Locations Prepositions and Locations  10 - Quantitative States  allgone big empty full little long tiny all a lot another any each every more much none some too  Descriptive Words Descriptive Words Descriptive Words Descriptive Words Descriptive Words Descriptive Words Descriptive Words Quantifiers and Articles Quantifiers and Articles Quantifiers and Articles Quantifiers and Articles Quantifiers and Articles Quantifiers and Articles Quantifiers and Articles Quantifiers and Articles Quantifiers and Articles Quantifiers and Articles Quantifiers and Articles  11- Changes in Physical, Locative, & Experiential States  fall find stay away into out  Action Words Action Words Action Words Prepositions and Locations Prepositions and Locations Prepositions and Locations  12 – Agents or Objects Causing Change in Physical States  build break clean close  Action Words Action Words Action Words Action Words 106  MCDI Predicate Words and Predicate Category (Meaning Type) Codes cook cover cut draw dry fix make open paint rip tear wash write  Action Words Action Words Action Words Action Words Action Words Action Words Action Words Action Words Action Words Action Words Action Words Action Words Action Words  13 – Agents or Objects Causing Change in Beneficiary or Locative States  buy catch drop dump give hold pick pour put share slide spill splash sweep take throw wipe  Action Words Action Words Action Words Action Words Action Words Action Words Action Words Action Words Action Words Action Words Action Words Action Words Action Words Action Words Action Words Action Words Action Words  14 – Self Movement Predicates (with and without affected objects)  bring bump carry climb go hit kick knock pull push ride  Action Words Action Words Action Words Action Words Action Words Action Words Action Words Action Words Action Words Action Words Action Words 107  MCDI Predicate Words and Predicate Category (Meaning Type) Codes  15 – Temporal Predicates  finish wait stop fast first last new old slow after before later now today tomorrow tonight yesterday when back try / try to then  Action Words Action Words Action Words Descriptive Words Descriptive Words Descriptive Words Descriptive Words Descriptive Words Descriptive Words Words About Time Words About Time Words About Time Words About Time Words About Time Words About Time Words About Time Words About Time Question Words Prepositions and Locations Helping Verbs Connecting Words  108  APPENDIX C-1 1B  Guttman Scale Analysis of Predicate Type Emergence Order in ASD Group The table in Appendix C-2 is a Guttman Scalogram Analysis showing the “emergence” order of each category type for each of the 49 participants in the ASD group at T1. To initially create this scale analysis, all predicate categories were ordered by the number of subjects who had met the acquisition criteria. In other words, the predicate categories on the columns on the right have more subjects who have “acquired” these types than those on the left. Each row in the table represents an individual subject and the categories that he/she had “acquired” at T1. A ‘ + ’ indicates that the child met the acquisition criteria for that predicate category while a ‘ – ’ indicates that he/she did not. To determine an order of predicate category acquisition, a line was drawn showing the point at which majority of the subjects met the acquisition criteria for each predicate type. Once this line was drawn, determining a potential set of meaning types that emerge together, a coefficient of reproducibility was computed to determine whether these ordered sets were reliable. All subjects who fell outside of this line were identified (indicated through the red boxes). These subjects were counted and were used to compute the coefficient of reproducibility. Coefficient of Reproducibility was at 0.94, indicating a reliable order. Final Emergence Order:  Emergence Order  Predicate Type  I  7  II  9L, 9P  III  3, 10  IV  5, 12, 13, 14  V  2, 15  VI  11, 6  VII  1  109  APPENDIX C-2 12B  Guttman Scale Analysis of Predicate Type Emergence Order in ASD Group  7 + + + + + + + + + + + + + + + + + + + + + + + + + + + + +  9L + + + + + + + + + + + + + + + + + + + +  9P + + + + + + + + + + + + + + + + + +  10 + + + + + + + + + + + + +  Predicate Category/Meaning Type 3 12 14 5 13 15 + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + -  2 + + + + +  11 + + +  6 + -  1 110  Guttman Scale Analysis of Predicate Type Emergence Order in ASD Group + + + + + + + + + + 39  + + + + + + + + + + 30  + + + + + + + + + + 28  + + + + + + + + + + 23  + + + + + + + + + + 23  + + + + + + + + + + 22  + + + + + + + + + + 19  + + + + + + + + + + 17  + + + + + + + + + + 16  + + + + + + + + + + 14  + + + + + + + + + 14  + + + + + + + + + + 13  + + + + + + + + + + 12  + + + + + + 6  111  

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