The acquisition of different classes of words in Spanish children with Down syndrome

The role of imageability in noun and verb acquisition in children with Down syndrome and their peers with typical development

Our main objective was to analyze the role of imageability in relation to the age of acquisition (AoA) of nouns and verbs in Spanish-speaking children with Down syndrome (DS) and their peers with typical development (TD). The AoA of nouns and verbs was determined using the MacArthur-Bates CDIs adapted to the profile of children with DS. The AoA was analyzed using a linear mixed-effect model, including factors of imageability, group, and word class, and controlling for word frequency and word length. This analysis showed that high imaginable and short words were acquired early. Children with DS acquired the words later than TD peers. An interaction between imageability and group indicated that the effect of imageability was greater in the DS group. We discuss this effect considering DS children's phonological memory difficulties. The overall results confirm the role that imageability and word length play in lexical acquisition, an effect that goes beyond word class.

Word type and modality in the emerging expressive vocabularies of preschool children with Down syndrome

BACKGROUND

Previous studies have explored the size and word type composition (nouns, predicates, etc.) of expressive vocabularies of preschool children with Down syndrome, both spoken and signed. Separately, overall preferences for modality of expression have also been explored.

AIMS

To extend previous findings by describing the relationships between expressive vocabulary size and both word type and modality of expression in the preschool period including changes to modality preference over time.

METHODS & PROCEDURES

Mothers of 35 children with Down syndrome, aged 36-66 months and attending the same early intervention programme, completed a version - with both spoken word and sign options - of the New Zealand MacArthur-Bates Communicative Development Inventory (CDI): Words and Sentences. Most mothers completed the CDI on multiple occasions across the duration of the study. Completions (n = 114) were analysed cross-sectionally and longitudinally in terms of (1) word type relative to vocabulary size, (2) modality of expression relative to word type and vocabulary size, and (3) individual trajectories in vocabulary size and modality of expression.

OUTCOMES & RESULTS

(1) Word type relative to vocabulary size was similar to previous studies with a greater proportion of the SOCIAL words being present in the children's vocabularies throughout, followed by NOUNS, PREDICATES and CLOSED class words, with proportions converging as vocabulary sizes increase. (2) An initial spoken word preference for SOCIAL and CLOSED class words and sign preference for NOUNS and PREDICATES was found, with more spoken words in larger vocabularies overall. (3) Individual trajectories were highly variable and also revealed temporary points of regression in overall expressive vocabulary size in some children. Children who shifted from reliance on sign to predominantly spoken word expression did so at different ages and at different vocabulary sizes. At school entry, while most of the children used both modalities, some children continued to rely on sign for most vocabulary items whereas others used only spoken words.

CONCLUSIONS & IMPLICATIONS

An appreciation of both the general trends and potential for individual variation in vocabulary structure, modality of expression and change over time will better position clinicians and education specialists to provide individually tailored support to both preschool and school-aged children with Down syndrome.

WHAT THIS STUDY ADDS

What is already known on this subject Preschool children with Down syndrome have been shown to demonstrate developmental patterns in overall conceptual vocabulary size and word type development broadly similar to typical development. The use of signed vocabulary has also been explored, but independently from word type development and with less attention to individual trajectories in either vocabulary size development or modality preferences throughout the preschool period than is necessary for clinical use. What this paper adds to existing knowledge This study found interactions between word type and modality of expression in relation to vocabulary size as well as a few temporary vocabulary size regressions similar to those found in much younger typically developing children. An initial spoken word preference for social and closed class words, and sign preference for nouns and predicates, was followed by a general trend towards spoken words for all word types as vocabulary (with some fluctuations) increased over time. Children demonstrated considerable individual variation in size of vocabulary and age at which they pivoted from a signed to a spoken word preference. Moreover, while most children used both modalities at school entry, a few retained a sign-only vocabulary and others had moved fully onto spoken word-only expression. What are the potential or actual clinical implications of this work? An understanding of both the general trends and individual variation in vocabulary structure and modality of expression development will better position clinicians and educational specialists to provide individually tailored support to children with Down syndrome.

Enhanced learning to improve letter knowledge in children with Down syndrome and severe intellectual disability: A case report

Children with Down syndrome and severe intellectual disability have difficulties in learning a language. Enhanced learning procedure, including mora segmentation is beneficial to understand letter-sound correspondence in such children.

Joint attention and vocabulary development in toddlers with Down syndrome and their peers with typical development: The role of maternal interactive style

PURPOSE

Joint attention is considered a prerequisite for language development. Although language is one of the most impaired domains in Down syndrome (DS), few studies have examined the relationship between caregiver behavior during episodes of joint attention and vocabulary development in these children. Consequently, our primary aim was to analyze the behaviors of caregivers of children with DS and of children with typical development (TD) in the early stages of vocabulary development. A second objective was to examine the kind of words that caregivers use to refer to the object that is the focus of attention. We also consider the concurrent relationship between joint attention and vocabulary development in both groups of children.

METHOD

We studied 28 children with DS and 28 children with TD, individually matched on mental age and gender, and their respective caregivers. The mean mental age for children with DS and children with TD was around 12 months. The mean chronological age of caregivers of children with DS and children with TD was around 35 years. Each child and his or her caregiver were video-recorded during a free-play session involving different objects.

RESULTS

Although the total time engaged in joint attention was greater among caregivers of children with DS, caregivers of both groups of children were more likely to direct than follow their child's attentional focus. The caregivers of children with DS used a greater number of appropriate terms to refer to the object of attention. We found no significant correlation in either group of children between vocabulary development and joint attention behaviors.

CONCLUSIONS

The results may be due to the fact that the children studied are still very young in developmental terms and have yet to develop all the skills required for joint attention. At this early stage, directing the child's attention would promote the development of joint attention. A possible explanation for the lack of a correlation between vocabulary development and joint attention is that children may use an associative mechanism in the early stages of lexical learning, and hence the learning of new words is a slow process.