Cross-Population Comparison of Expressive Language Profiles in Mandarin-Exposed Children with ASD, MR, and LD

Background:

Cross-population comparison of language development is beneficial to reveal the similarities and differences between children with autism spectrum disorders (ASD) and those with other language impairments. Studies in western children with ASD have yielded evidence for their core linguistic abilities in lexical and grammatical development, in contrast to the more impaired pragmatic abilities (Ellis Weismer et al., 2011; Geurts & Embrechts, 2008; Tager-Flusberg et al., 1990). Cross-population studies in children with ASD speaking typologically different languages (as a comparison with other language delayed groups) are needed to unveil the unique and universal language profiles in children with ASD across countries.

Objectives:

To compare expressive language profiles including lexical, grammatical and pragmatic skills among children with ASD, children with mental retardation and children with language disorder, via the Putonghua Communicative Development Inventory: Words and Sentences (PCDI-Toddler Form).

Methods:

Parents of 114 preschool children with language impairments participated in this study, including 41 children with ASD (the ASD group), 41 children with mental retardation (the MR group), and 32 children with language disorder (the LD group). These three groups of children were matched on age (ASD: 47.80±13.82 months, MR: 48.95±16.81 months, LD: 41.84±13.45 months, F（2,110）= 2.28, p>.05) as well as the total vocabulary production score via the PCDI lexical checklist (ASD: 225.20±233.78, MR: 221.71±270.21, LD:279.13±313.14, F(2,111) =.49, p>.05). However, the ASD group had significantly higher scores on the Autism Behavior Checklist than the other two groups (ASD:83.07±21.67, MR:39.00±16.21, LD:32.45±13.95, F（2,100）=72.322, p<.001). Children’s lexical, grammatical and pragmatic levels were compared through the completed PCDI-Toddler Form.

Results:

(1) While matched on the total vocabulary production level, these three groups were comparable in the five lexical subcategories: nouns, verbs, pronouns, quantifiers and question words (Fs(2,111)=.27-2.15, ps>.05). (2) In the grammatical aspect, three groups of children did not differ on most items of “words and sentences”, “combining” (Χs²=.30-5.22, ps>.05), MLU and grammatical complexity (Fs(2,111)=.10 and .59, ps>.05). But further pairwise Chi-square test revealed that the ASD group used fewer perfective/experiential aspect markers “le” or “guo” than the LD group (17.1% vs. 37.5%, Χ²=3.90，p<.05). (3) Three groups were equivalent on most of the pragmatic items in the subscale of “how to use words “(Χs²=1.04-5.90, ps>.05). Pairwise chi-square tests revealed that though the MR and LD groups did not differ in their pragmatic skills, the ASD group displayed a relatively weaker command on “describing past events/people” (17.1%) than the MR group (37.5%) and the LD group (37.5%), Χ²=4.27 and 3.90, ps <.05.

Conclusions:

In general, Mandarin-exposed children with ASD exhibited similar levels of lexical and grammatical abilities as the MR group and the LD group. Consistent with Ellis Weimer et al. (2011), this is further evidence for the dimensional account that different populations of children with language delays demonstrated core linguistic abilities. However, Mandarin-exposed children with ASD’s deficits in the use of perfective/experiential marker and the description of past events/people may reflect their special difficulties in expressing past events, both grammatically and pragmatically (Eigsti, et al., 2007; Jyotishi et al., 2017).