The biological basis of language: insight from developmental grammatical impairments

Specific language impairment (SLI), a genetic developmental disorder, offers insights into the neurobiological and computational organization of language. A subtype, Grammatical-SLI (G-SLI), involves greater impairments in ‘extended’ grammatical representations, which are nonlocal, hierarchical, abstract, and composed, than in ‘basic’ ones, which are local, linear, semantic, and holistic. This distinction is seen in syntax, morphology, and phonology, and may be tied to abnormalities in the left hemisphere and basal ganglia, consistent with new models of the neurobiology of language which distinguish dorsal and ventral processing streams. Delineating neurolinguistic phenotypes promises a better understanding of the effects of genes on the brain circuitry underlying normal and impaired language abilities.Psycholog

Phonetic categorisation and cue weighting in adolescents with Specific Language Impairment (SLI)

This study investigates phonetic categorisation and cue weighting in adolescents and young adults with Specific Language Impairment (SLI). We manipulated two acoustic cues, vowel duration and F1 offset frequency, that signal word-final stop consonant voicing ([t] and [d]) in English. Ten individuals with SLI (14.0–21.4 years), 10 age-matched controls (CA; 14.6–21.9 years) and 10 non-matched adult controls (23.3–36.0 years) labelled synthetic CVC non-words in an identification task. The results showed that the adolescents and young adults with SLI were less consistent than controls in the identification of the good category representatives. The group with SLI also assigned less weight to vowel duration than the adult controls. However, no direct relationship between phonetic categorisation, cue weighting and language skills was found. These findings indicate that some individuals with SLI have speech perception deficits but they are not necessarily associated with oral language skills

Who did Buzz see someone? Grammaticality judgement of wh-questions in typically developing children and children with Grammatical-SLI

This paper tests claims that children with Grammatical(G)-SLI are impaired in hierarchical structural dependencies at the clause level and in whatever underlies such dependencies with respect to movement, chain formation and feature checking; that is, their impairment lies in the syntactic computational system itself (the Computational Grammatical Complexity hypothesis proposed by van der Lely in previous work). We use a grammaticality judgement task to test whether G-SLI children's errors in wh-questions are due to the hypothesised impairment in syntactic dependencies at the clause level or lie in more general processes outside the syntactic system, such as working memory capacity. We compare the performance of 14 G-SLI children (aged 10–17 years) with that of 36 younger language-matched controls (aged 5–8 years). We presented matrix wh-subject and object questions balanced for wh-words (who/what/which) that were grammatical, ungrammatical, or semantically inappropriate. Ungrammatical questions contained wh-trace or T-to-C dependency violations that G-SLI children had previously produced in elicitation tasks. G-SLI children, like their language controls, correctly accepted grammatical questions, but rejected semantically inappropriate ones. However, they were significantly impaired in rejecting wh-trace and T-to-C dependency violations. The findings provide further support for the CGC hypothesis that G-SLI children have a core deficit in the computational system itself that affects syntactic dependencies at the clause level

Grammatical feature dissimilarities make relative clauses easier: A comprehension study with Italian children

The Relativized Minimality approach to A′-dependencies (Friedmann et al., 2009) predicts that headed object relative clauses (RCs) and which—questions are the most difficult, due to the presence of a lexical restriction on both the subject and the object DP which creates intervention. We investigated comprehension of center-embedded headed object RCs with Italian children, where Number and Gender feature values on subject and object DPs are manipulated. We found that, Number conditions are always more accurate than Gender ones, showing that intervention is sensitive to DP-internal structure. We propose a finer definition of the lexical restriction where external and syntactically active features (such as Number) reduce intervention whereas internal and (possibly) lexicalized features (such as Gender) do so to a lesser extent. Our results are also compatible with a memory interference approach in which the human parser is sensitive to highly specific properties of the linguistic input, such as the cue-based model (Van Dyke, 2007)