A Comparison of Syntactic Skills in Children with Autism or SLI: Similar Performance, but Different Errors

Background: , Language impairment is common (although not universal) feature of autism-spectrum-disorder (ASD). It has been widely argued that language difficulties that affect some people with ASD can be understood as a subtype of specific-language-impairment (SLI). Past studies have found that children with syntactic SLI show a very consistent pattern of impairment in language tasks assessing syntatically complex structures, including the comprehension and production of relative clauses, the repetition of syntactically complex sentences, and WH question production.

Objectives: , The objective of the current study was to see whether children with ASD would show the same error patterns as children with SLI. The tasks chosen for this research were the tasks that were the most sensitive to the syntactic impairment in SLI. 

Methods: , Participants were 18 native Hebrew-speaking autistic children (16 boys) aged 8; 3 to 17; 6 years (mean = 11; 7, SD = 1; 8), who were rigorously diagnosed by a multi-disciplinary panel. Each child was administered six tasks: (1)  picture description task involving the production of subject- and object-relative clauses; (2) production of Wh questions; (3) comprehension of relative clauses and which-questions in a sentence-picture matching task; (4) comprehension of relative clauses in a comprehension questions task; (5) repetition of syntactically complex sentences including object relatives, topicalized sentences, Wh questions, embedded sentences, structures with verb movement, compared with simple sentences, (6) verb inflection completion (subject-verb agreement and tense).  These tasks were also administered to Hebrew-speaking children with syntactic-SLI. All comparisons between groups were conducted by applying the standard chi test and two-tailed T-test. We accepted p <0.05 as the minimum acceptable level of significance.

Results: , The individual variation between ASD subjects was considerable. Although some of the participants with ASD showed significant difficulties in performing the syntactic tasks, the error patterns that were found in this group were markedly different from the known pattern of errors in previous studies of SLI. In the relative-clause and Wh questions production tasks, the children with ASD made errors that included many pragmatic and morphological errors, which do not occur in SSLI production. Furthermore, whereas SSLI children produce subject questions well, the ASD children struggled both in subject and in object questions. In the relative clause comprehension task some ASD children did not show the asymmetry between subject- and object relatives, found for SSLI.  In the repetition task, unlike children with SLI who had either errors that where lexical or grammatical, ASD children showed errors of perseveration, adding of information, answering a question instead of repeating it, substituting a target word with a word close to it semantically. 

Conclusions: , This study challenges the view that language difficulties in ASD reflect comorbid SLI. Indeed, the errors of children with ASD did not look like those of any other population that we have studied in the past including children with intellectual disability or orally trained hearing impairment. The difficulties the participants with ASD showed on the syntactic tasks were of a completely different nature, which points to a different nature of the underlying deficit.