International Meeting for Autism Research (London, May 15-17, 2008): VOCABULARY AND GRAMMAR DEVELOPMENT IN TODDLERS ON THE AUTISM SPECTRUM COMPARED TO LATE TALKERS WITHOUT AUTISM

Saturday, May 17, 2008

Champagne Terrace/Bordeaux (Novotel London West)

S. Ellis-Weismer , Communicative Disorders/Educational Psychology/Psychology, University of Wisconsin-Madison, Madison, WI

M. A. Gernsbacher , Psychology, University of Wisconsin-Madison, Madison, WI

E. Roos , Communicative Disorders, University of Wisconsin-Madison, Madison, WI

C. Karasinski , Communicative Disorders, University of Wisconsin-Madison, Madison, WI

A. Esler , Waisman Center, University of Wisconsin-Madison, Madison, WI

S. Stronach , Waisman Center, University of Wisconsin-Madison, Madison, WI

Background: Investigation of early language development in autism has both theoretical and practical significance. This study addressed whether language delays or deficits noted in autism constitute a unique phenomenon (‘distinct category account’), or whether they overlap with other language difficulties (‘dimensional account’). Research focused on contrasting the distinct category vs. dimensional accounts has implications for phenotypic markers of autism as well as treatment. The current study explored the overlap in language abilities in verbal toddlers on the autism spectrum (AUT) and late talkers (LT) without autism.

Objectives:

This study examined whether autism spectrum toddlers and late talkers, matched on overall productive vocabulary, display similar use of 1) semantic categories; 2) psychological terms; and 3) word combinations and grammatical complexity.

Methods:

Two groups of toddlers (22-35 months) participated: 21 AUT and 21 LT. AUT diagnoses were determined using comprehensive diagnostic evaluations including the ADI-R and ADOS. Groups were matched on parent report of words produced (± 6 words) on the Communicative Development Index: Words and Sentences (CDI-WS).

Results:

Vocabulary matching resulted in significant mean age differences between the groups (AUT=30 mo, LT=25 mo). Comparison of the proportions of words within 22 semantic categories on the CDI-WS revealed equivalent usage for all categories except action words (higher for AUT). An analysis of psychological terms (e.g., “happy”) revealed no significant differences for any of five categories evaluated or overall proportion of terms used. With respect to grammatical abilities, there were no significant differences in CDI complexity scores or the proportion of AUT vs. LT toddlers who were combining words.

Conclusions:

When matched on overall vocabulary level, 30-month AUT toddlers exhibited word use patterns and early grammatical abilities that were qualitatively very similar to 25-month late talkers without autism. These initial findings support the dimensional account of language delay relative to vocabulary/grammar in autism.

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