Robin S. Chapman

Behavioral phenotype of individuals with Down syndrome.

Evidence is reviewed for a developmentally-emerging behavioral phenotype in individuals with Down syndrome that includes significant delay in nonverbal cognitive development accompanied by additional, specific deficits in speech, language production, and auditory short-term memory in infancy and childhood, but fewer adaptive behavior problems than individuals with other cognitive disabilities. Evidence of dementia emerges for up to half the individuals studied after age 50. Research issues affecting control group selection in establishing phenotypic characteristics are discussed, as well as the possible genetic mechanisms underlying variation in general cognitive delay, specific language impairment, and adult dementia. MRDD Research Reviews 2000;6:84-95. Wiley-Liss, Inc.

Language development in children and adolescents with Down syndrome

This review of recent work on language development in children and adolescents with Down syndrome focuses on sentence structure, grammatical words, and vocabulary. Evidence is summarized for a specific expressive language impairment, over and above the cognitive delay associated with the syndrome. A profile of strengths (lexical comprehension) and deficits (lexical and sentence production) is identified. Acquisition of productive syntax is shown to be ongoing in adolescence, without evidence of limits to learning at the onset of adolescence or the advent of complex syntax. Additional difficulties in verb and grammatical morpheme acquisition are identified. Predictors of individual variation in performance and competing explanations of language deficit are discussed briefly. Interventions shown to increase communicative effectiveness are summarized. MRDD Research Reviews 1997;3:307–312.

Language Skills of Children and Adolescents with Down Syndrome: I. Comprehension.

This study investigates the development of vocabulary and syntax comprehension skills cross-sectionally in 48 children and adolescents with Down syndrome (Trisomy 21), aged 5-20 years, in comparison to 48 control children aged 2-6 years matched statistically for nonverbal mental age and mothers years of education. Age-equivalent scores on vocabulary (PPVT-R) and syntax (TACL-R) comprehension tests differed in the Down syndrome group but not the control group; vocabulary comprehension was relatively more advanced than syntax. Age-equivalent scores on nonverbal cognitive subtests of pattern analysis and short-term memory for bead arrangements (Stanford-Binet, 4th ed.) also differed for the Down syndrome group but not the control group, indicating an unusual pattern of nonverbal cognitive function in the Down syndrome group. Stepwise multiple regression analyses showed that chronological age and mean mental age, collectively, accounted for 78% of the variability in vocabulary comprehension and 80% of the variability in syntax comprehension in the Down syndrome group, with total passes on a hearing screening accounting for an additional 4% in each case. Implications for research are discussed.

Children's Language Learning: An Interactionist Perspective

This review of childrens language learning considers historical accounts of acquisition and individual variation, recent advances in methods for studying language learning, research on genetic and environmental input that have contributed to the interactionist perspective, and the relevance of cross-disciplinary work on language disorders and the biology of learning to future theories. It concludes that the study of childrens language development is converging on an interactionist perspective of how children learn to talk, incorporating the contributions of both nature and nurture to emergent, functional language systems. Language learning is viewed as an integration of learning in multiple domains.

Complex Sentence Production by Adolescents with Down Syndrome.

The use of complex syntax was investigated in narrative language samples of older children and adolescents with Down syndrome ( n = 24) and a group of typically developing children matched on mean length of utterance. Both groups used conjoined and subordinate sentence forms and did not differ significantly in either the proportion of utterances containing complex sentences or in the variety of complex sentence types used. The analysis of developmental patterns suggested a similar order of acquisition across groups. The findings indicate that syntactic development in individuals with Down syndrome continues into late adolescence and is not limited to simple syntax. This study does not support earlier findings of a critical period effect in syntactic development in Down syndrome based on age or syntactic complexity.

Verb use by individuals with Down syndrome

Production of grammatical and lexical verbs in narratives from 29 individuals with Down syndrome and 29 typically developing control subjects matched on linguistic level (Browns Stages 3, 4, and 5) was examined. We addressed recent theories proposing that verbs are central to syntactic development (Tomasello & Merriman, 1995). Consistent with predictions from the child talk model (Chapman et al., 1992), the individuals with Down syndrome produced fewer lexical or grammatical verbs per utterance compared to the control group but produced a greater diversity of lexical verbs. The findings suggest that the well-documented syntactic deficits evidenced by individuals with Down syndrome may reflect difficulty in accessing verbs when constructing utterances. This difficulty may stem from deficits in auditory short-term memory.

Mothers' speech to their 1-year-old infants in home and laboratory settings

The speech of mothers and their 1-year-old infants was compared in the home and in the laboratory playroom. The home and laboratory settings were similar for measuring the number of actual words that infants spoke and were similar for measuring the complexity of the mothers speech, including the number of different words, the type-token ratio, and the length of the utterances. Infants vocalized at similar rates in the two settings, but mothers spoke at a faster rate in the laboratory playroom. The usefulness of a preliminary warm-up period was supported by the finding that for the second half of the sessions, mothers slowed their rate of speech and increased the complexity of their speech.

Children's Judgment and Recall of Causal Connectives: A Developmental Study of "Because," "So," and "And"

The present study examined the acceptability judgments and recall performance of children aged 6,9, and 11 years with sentences expressing psychological cause-effect relations. Thirty-two sentences containing “because” medially, “because” initially, “so,” and “and” were generated from four clause pairs. Both probable and improbable event orders were used. The results indicated that children preferred “because” to “so” or “and” for statements of psychological causality. However, on both tasks, first and third graders frequently failed to attend to the temporal ordering specified by each sentence construction. The younger children also tended to judge all sentences acceptable, suggesting that they were concerned only with the probable association of event pairs, and not with the usual order of the events. Order of mention strategies did not occur in any group, suggesting that they arise only when children cannot make interpretations based on probable order of events. The data also indicated that the recall task is an unreliable index of rules for comprehension and production.

The effect of story presentation rates on story retelling by individuals with Down syndrome

The current study examined the effect of story presentation rates on story recall performance in 35 individuals with Down syndrome and 3 control groups (35 mental age matched, 35 syntax comprehension matched, and 35 syntax production matched children). Three short audiotaped stories were presented to each individual at three different rates (normal, storyteller [slow with expressive inflections], and slow rate). The effect of group but not rate was significant. Individuals with Down syndrome recalled more content words than the production-matched group and the productionmatched group recalled fewer content words than the mental age matched and comprehensionmatched groups. The results were interpreted in relation to working memory deficits in individuals with Down syndrome, developmental change in story recall of typically developing children, and the contribution of syntax comprehension to story recall. Language production involves multiple levels of processing, including message formation, compilation of the linguistic components (phonetic phonological, syntactic, semantic, and pragmatic elements), and speech execution (Bock, 1982, 1996; Griffin & Bock, 1998). Although these processes occur relatively automatically in typically developing children, trade-off effects can be observed when the speaking task is effortful (Streim & Chapman, 1987). Individuals with Down syndrome (DS) experience deficits in morphosyntactic production in spontaneous narrative and conversational samples (Chapman, 1997; Vicari, Caselli, & Tonucci, 2000). Because individuals with DS may experience greater effort in morphosyntactic processes than individuals at the same or higher expressive language levels, tasks that reduce information processing load compared to spontaneous narrative might benefit them more than controls matched

Comprehension Monitoring: A Developmental Effect?

This study investigated whether children’s comprehension monitoring skills follow a developmental effect as postulated by Dollaghan and Kaston (1986) in their treatment sequence for developing comp...