Novel word acquisition in children with Down syndrome: does modality make a difference?

Signing is a commonly used intervention technique for children with cognitive impairments who have expressive language delays. Novel word learning in three conditions (signed only, spoken only, signed and spoken combined) was compared for children with Down syndrome (2;1 to 5;2) and mental-age matched control children (1;4 to 2;6). Spontaneous imitations and responses to production and comprehension probes were examined after 5, 10, and 15 word exposures. No group differences in frequency of imitations or productions were obtained. The frequency of imitations was highest in the combined condition. Probed productions were infrequent, although novel words were produced most often in spoken and combined conditions. For both imitated and probed productions in the combined condition, the spoken portion was almost exclusively produced. Across conditions, children with Down syndrome comprehended fewer words than did control children. The evidence for and explanations of the facilitative effect of signs and the advantage of dual-method presentation are discussed.

Predicting language production in children and adolescents with Down syndrome: the role of comprehension.

Predictors of language production skills in 12-minute narratives are investigated cross-sectionally in 48 children and adolescents with Down syndrome (trisomy 21), aged 5 to 20 years, in comparison to 48 control children aged 2 to 6 years matched statistically for nonverbal mental age and mother's years of education. Two models were evaluated by hierarchical regression analyses using predictors drawn from the domains of group membership, chronological age, cognition, socioeconomic status, and hearing screening status (Model I) and, additionally, comprehension performance (Model II). Results showed that Model II was more successful. In the DS group, it explained 68% of the variability in number of different words, 80% in MLU, and 32% in intelligibility. Corresponding percentages for the control group were 72%, 71%, and 26%. A mechanism linking comprehension of input to early stages of production practice through activation of the early speech motor area is proposed.

Sequential recall in individuals with Down syndrome.

This study investigated whether memory for item order is selectively impaired in a group of individuals with Down syndrome. The ability to recall correctly ordered information was examined using two auditory tasks--narrative recall (Time 1) and digit span (Time 2)--and a nonverbal, visual task (Time 2) on which mental age (MA) matching was partially determined. Although subjects with Down syndrome recalled significantly less information than MA-matched controls on both auditory tasks, replicating previous findings of auditory memory span deficits, no differences in the ordering of recalled information were found. Nor did the groups differ in the relative frequency of ordering errors in the visual task. Neither a pervasive deficit in sequential processing nor a specific difficulty in recalling the order of information is supported. Alternative accounts are discussed.

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 mother's 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.

Fast mapping of words in event contexts by children with Down syndrome.

Fast mapping of novel words for objects was compared in 48 children and adolescents with Down syndrome (ages 5:6-20:6), who were delayed in expressive language acquisition compared to mental age, and 48 normally developing children matched for mental age (chronological ages 2:0-6:0). Normal and Down syndrome groups did not differ in their ability to infer a connection between the novel word and referent (100% vs. 100%), to comprehend the novel word after a single exposure (83% vs. 73%), and to recall the location in which they hid the novel referent (83% vs. 75%). Nor did they differ in their ability to produce the novel word correctly (at least two out of three phonemes in order: 48% vs. 40%). When retested after an hour of other activity, only the production task showed a significant, and comparable, decrement. Comparing youngest and oldest quarters of each group showed improved memory for location in both, improved comprehension in the Down syndrome group, and improved production in the control group. Adults (n = 12), in contrast, performed perfectly on all tasks except the delayed word production. Neither intelligibility differences nor use of real word labels accounts for the failure to find a difference between groups. Fast mapping skills were unrelated to expressive language deficit in these children with Down syndrome.