A qualitative analysis of general receptive vocabulary of adolescents with Down syndrome

Emotional Lexicon in Down Syndrome

We studied comprehension of emotion versus concrete/abstract words in Down syndrome (DS). Study 1 compared 26 participants with DS and 26 typically developing (TD) children matched on verbal ability. Results showed no difference between groups. Study 2 assessed whether chronological age (CA) and (non)verbal abilities predicted developmental trajectories of comprehension in 36 children with DS and 143 TD children. For the latter, these variables predicted comprehension of all three word types. For the former, receptive vocabulary predicted comprehension of all word types, but CA and nonverbal reasoning only predicted comprehension of concrete words. This suggests that people with DS have no specific emotional lexicon deficit. Supporting their general lexical development would help them access abstract and emotional meanings.

On the Developmental Trajectories of Relational Concepts Among Children and Adolescents With Intellectual Disability of Undifferentiated Etiology

The aim of this study was to examine the developmental trajectories of comprehension of relational concepts among 557 participants with intellectual disability (ID) of undifferentiated etiology (M age  =  12.20 years, SD  =  3.18) and 557 typically developing (TD) participants (M age  =  4.57 years, SD  =  0.80). Logistic regression analyses, with nonverbal cognitive level entered first in the equations, showed only negligible differences with regard to the discriminative power of each of the 72 concepts used as outcome variables, and moderate differences in difficulty for only three items. A moderate mixed effect (i.e., combining a group difference in difficulty and discriminative power) was observed for a fourth item. It is concluded that the developmental trajectories of relational concepts are similar for participants with or without ID. The implications and limitations of the study are discussed.

Does the Development of Syntax Comprehension Show a Premature Asymptote Among Persons With Down Syndrome? A Cross-Sectional Analysis

Uncertainty persists regarding the post-childhood trajectory of syntactic acquisition of persons with Down syndrome (DS). In some studies, asymptote is reached in the early teens, whereas others find syntax continuing to develop at least into early adulthood. This study addressed the issue using a cross-sectional approach. Receptive syntax and vocabulary were tested in 62 children, adolescents and young adults with DS matched on chronological age and cognitive level with 62 participants with intellectual disability (ID) of undifferentiated etiology. On both tests there were significant effects of chronological age and diagnosis, but the chronological age × diagnosis interactions were nonsignificant. We concluded that comprehension of vocabulary and syntax does not asymptote prematurely in individuals with DS relative to those with other forms of ID.

An Item Analysis of the French Version of the Test for Reception of Grammar Among Children and Adolescents With Down Syndrome or Intellectual Disability of Undifferentiated Etiology

PURPOSE

An item analysis of Bishop's (1983) Test for Reception of Grammar (TROG) in its French version (F-TROG; Lecocq, 1996) was conducted to determine whether the difficulty of items is similar for participants with or without intellectual disability (ID).

METHOD

In Study 1, responses to the 92 F-TROG items by 55 participants with Down syndrome (DS), 55 with ID of undifferentiated etiology (UND), and 55 typical children (TYP) matched on their F-TROG total score were compared using the transformed item difficulties method, a statistical approach designed to detect differential item functioning (DIF) between groups. In Study 2, an additional comparison involving 526 TYP participants and 526 participants with UND was conducted to increase the statistical power of the analysis.

RESULTS

The difficulty of items was highly similar whatever the sample size or clinical status of participants. Fewer than 3.5% of the items were flagged as showing DIF.

CONCLUSIONS

Tests such as the TROG can be used with confidence in clinical practice as well as in research studies comparing participants with or without ID. Methods designed for investigating potential internal test bias-such as done here-should be more regularly employed in the developmental disability field to affirm the absence of DIF.

Receptive vocabulary analysis in Down syndrome

The present study is an in-depth examination of receptive vocabulary in individuals with Down syndrome (DS) in comparison to control groups of individuals of similar nonverbal ability with typical development (TD) and non-specific etiology intellectual disability (ID). Verb knowledge was of particular interest, as it is known to be a predictor of later syntactic development. Fifty participants with DS, aged 10-21 years, 29 participants with ID, 10-21 years, and 29 participants with TD, 4-9 years, completed measures of receptive vocabulary (PPVT-4), nonverbal ability (Leiter-R), and phonological memory (Nonword Repetition subtest of the CTOPP). Groups were compared on percentage correct of noun, verb and attribute items on the PPVT-4. Results revealed that on verb items, the participants with ID performed significantly better than both participants with DS and TD, even when overall receptive vocabulary ability and phonological memory were held constant. Groups with DS and TD showed the same pattern of lexical knowledge, performing better on nouns than both verbs and attributes. In contrast, the group with ID performed similarly on nouns and verbs, but worse on attributes.