Leonard Abbeduto

Receptive language skills of adolescents and young adults with down or fragile X syndrome.

We investigated the receptive language of adolescents and young adults with Down syndrome (n = 25) or fragile X syndrome (n = 19). We were interested in syndrome differences and gender differences within fragile X. Comparison of the syndromes and MA-matched typically developing children (n = 24) revealed that individuals with the syndromes differed in relative achievements across the domains of receptive vocabulary, receptive syntax, and nonverbal cognition as well as in the organization of their linguistic knowledge. Comparison of males and females with fragile X revealed that each displayed synchronous development across the three domains, despite the fact that the receptive language levels of females surpassed that of males.

Language and communication in fragile X syndrome

In this article, we describe the language and communication problems of individuals with fragile X syndrome (FXS). FXS is a common genetic disorder resulting from a single-gene mutation on the X chromosome. It is associated with a wide spectrum of physical, behavioral, cognitive, and language problems. Males are typically more severely affected than females, with the vast majority of males having mental retardation. Language and communication are negatively affected by problems in oral-motor structure and function and by conductive hearing loss associated with recurrent otitis media. Speech problems of males with FXS include variability in rate and stuttering-like repetition of sounds. The pattern of speech problems displayed by males is unique to FXS and may reflect a form of developmental dyspraxia. Lexical development is serious delayed in males with FXS. It is less clear, however, whether lexical development keeps pace with achievements in cognitive development and whether receptive and expressive vocabularies are equally impaired. Morphosyntactic development is delayed in males with FXS, with receptive morphosyntax being mental-age-appropriate. It is less clear whether expressive morphosyntactic keeps pace with mental age in affected males. Communication problems are characteristic of both males and females and include features that are syndrome-specific. Most notable among the features displayed by males with FXS is perseveration on a word, phrase, or topic in conversation. Several hypotheses have been advanced to explain this perseveration, but the most promising focus is on hyperarousal and frontal-lobe-executive function deficits. Females with FXS display a run-on, disorganized, and tangential style of conversation that may result from their welldocumented frontal-lobe-executive function deficits. Language and communication intervention for affected individuals requires coordination of medical and behavioral approaches, with the involvement of professionals from several disciplines. Future research must focus on females, on language problems suggested by clinical experience, and on connections between language and communication problems and problems at the neurological and molecular genetic levels.

Children's knowledge of the presuppositions of know and other cognitive verbs

This study investigated the development of knowledge about the presuppositions of cognitive verbs that take sentential complements. The verbs included factives, which presuppose the truth of their complements, and nonfactives, which carry no such presupposition. Three tasks assessed childrens ability to ( a ) assign truth values to complements according to the presuppositions of the main verbs; ( b ) select verbs to describe peoples mental states; and ( c ) state the presuppositions of the verbs in definitions. The results indicated that the presuppositions of the factives know, forget , and remember and the nonfactive think are not learned until age 4. Believe , which has factive and nonfactive properties, is mastered after age 7. The childrens performance differed across tasks due to variations in processing requirements.

Language and Communication in Fragile X Syndrome

In this article, we describe the language and communication problems of individuals with fragile X syndrome (FXS). FXS is a common genetic disorder resulting from a single-gene mutation on the X chromosome. It is associated with a wide spectrum of physical, behavioral, cognitive, and language problems. Males are typically more severely affected than females, with the vast majority of males having mental retardation. Language and communication are negatively affected by problems in oral-motor structure and function and by conductive hearing loss associated with recurrent otitis media. Speech problems of males with FXS include variability in rate and stuttering-like repetition of sounds. The pattern of speech problems displayed by males is unique to FXS and may reflect a form of developmental dyspraxia. Lexical development is serious delayed in males with FXS. It is less clear, however, whether lexical development keeps pace with achievements in cognitive development and whether receptive and expressive vocabularies are equally impaired. Morphosyntactic development is delayed in males with FXS, with receptive morphosyntax being mental-age-appropriate. It is less clear whether expressive morphosyntactic keeps pace with mental age in affected males. Communication problems are characteristic of both males and females and include features that are syndrome-specific. Most notable among the features displayed by males with FXS is perseveration on a word, phrase, or topic in conversation. Several hypotheses have been advanced to explain this perseveration, but the most promising focus is on hyperarousal and frontal-lobe-executive function deficits. Females with FXS display a run-on, disorganized, and tangential style of conversation that may result from their welldocumented frontal-lobe-executive function deficits. Language and communication intervention for affected individuals requires coordination of medical and behavioral approaches, with the involvement of professionals from several disciplines. Future research must focus on females, on language problems suggested by clinical experience, and on connections between language and communication problems and problems at the neurological and molecular genetic levels. r 1997 Wiley-Liss, Inc. MRDD Research Reviews 1997;3:313–322.

Narrative development in adolescents and young adults with fragile x syndrome.

The narratives of 18 adolescents and young adults with fragile X syndrome were compared to those of 23 adolescents with Down syndrome and 21 typically developing children matched for nonverbal MA. Narratives were elicited using a wordless picture book and analyzed for use of narrative evaluation, linguistic productivity, and complexity. Results revealed that the individuals with fragile X syndrome produced significantly fewer different types of narrative evaluation, but more grammatically acceptable utterances than did the youth with Down syndrome. There was no significant difference between the participants with fragile X syndrome and their typically developing nonverbal-MA matches. Results suggest that a variety of language measures and contexts are needed to gain a full understanding of the language abilities of individuals with fragile X syndrome.

The Effects of Linguistic Complexity on Children's and Adults' Motor Programming of Speech.

The role of syntactic/semantic structure in the motor programming of speech by 5-year-olds, 8-year olds, and adults was investigated. Subjects repeated sentences, each at maximum rate, on numerous, consecutive trials. Linguistically simple and complex sentence types, matched on rhythm, were selected for each age. On a current model, linguistic structure determines programming unit size with increased size resulting in shorter and less variable repetition durations. Repetition durations were found to be shorter for simple than for complex sentences at all ages. However, linguistic complexity affected durational variability only for adults. A new model is proposed to account for these results.

Identifying speech acts from contextual and linguistic information.

We conducted an experiment to examine the comprehension of interrogatives such as Could you make the pencil roll?, which can be intended as yes—no questions, as directives to perform an action, or as both. Clark (1979) has claimed that the comprehension of such sentences is governed by, among other things, the answer obviousness rule; that is, listeners are more likely to interpret such a sentence as a question if the question posed is non-obvious to the speaker. One purpose of the present experiment was to test Clarks claim. A second purpose was to begin identifying the types of contextual information listeners use in comprehending speech acts. The final purpose was to provide data relevant to the controversy about whether listeners evaluate the syntactically direct, literal meaning of a sentence in the course of arriving at a syntactically indirect interpretation. We found that listeners follow an answer obviousness rule, utilize their knowledge of objects and the actions they allow as context for sentence interpretation, and do sometimes evaluate the syntactically direct reading of a sentence before arriving at an indirect speech act.