Grammatical markers are not uniformly impaired across speakers of different languages, even when speakers share a diagnosis and the marker in question is grammaticalized in a similar way in these languages. The aim of this work is to demarcate, from a cross-linguistic perspective, the linguistic phenotype of three genetically heterogeneous developmental disorders: specific language impairment, Down syndrome, and autism spectrum disorder. After a systematic review of linguistic profiles targeting mainly English-, Greek-, Catalan-, and Spanish-speaking populations with developmental disorders (n = (...) 880), shared loci of impairment are identified and certain domains of grammar are shown to be more vulnerable than others. The distribution of impaired loci is captured by the Locus Preservation Hypothesis which suggests that specific parts of the language faculty are immune to impairment across developmental disorders. Through the Locus Preservation Hypothesis, a classical chicken and egg question can be addressed: Do poor conceptual resources and memory limitations result in an atypical grammar or does a grammatical breakdown lead to conceptual and memory limitations? Overall, certain morphological markers reveal themselves as highly susceptible to impairment, while syntactic operations are preserved, granting support to the first scenario. The origin of resilient syntax is explained from a phylogenetic perspective in connection to the “syntax-before-phonology” hypothesis. (shrink)

The possibility and extent of thought without language have been subject to much controversy. Insight from non- or minimally verbal humans can inform this debate empirically. Since most such individuals are on the autism spectrum, of which they make up a sizable 25–30%, an important connection between language and autism transpires. Here we propose a model which makes sense of this link and explains why the non-verbal human mind, as present evidence suggests, represents a fundamentally different cognitive phenotype. This model (...) views the relevant part of the autism spectrum as reflecting the breakdown of a cognitive phenotype of which language is an inherent element and which will manifest principled limitations in the latter's absence. (shrink)

In this review, we summarize studies investigating comprehension of three core grammatical structures (Subject-Verb-Object word order, grammatical aspect and wh-questions) in diverse samples of Mandarin-acquiring preschoolers with ASD, all utilizing the Intermodal Preferential Looking (IPL) paradigm. Results showed that children with ASD, though they were delayed in chronological age and expressive language (including significantly lower vocabulary production scores), acquired various grammatical constructions similarly to their typically developing peers. Moreover, Mandarin-acquiring preschoolers with ASD demonstrated similar acquisition patterns of these three core (...) grammatical structures, as has been reported in previous IPL studies among English-acquiring children with ASD (Naigles & Fein, 2017). Thus, the results testify that universal underlying mechanisms are playing vital roles in grammatical acquisition of children with ASD across languages (e.g., the setting of word order parameters, the preservation of functional morphemes, the universal operation of WH-Movement), despite their pervasive social cognition impairments. These findings suggest that core grammatical knowledge may be preserved in children with ASD, even in the face of radical differences in language environment and social/communicative deficits, supporting the contribution of the language faculty in autistic language acquisition. The results shed light on the sharp contrast between linguistic competence (governed by the internal computational system of the language faculty) vs. linguistic performance (affected by loci of impairment in the sensory-motor and the conceptual-intentional interfaces) in ASD. Furthermore, the results highlight the dissociation between the lexical vs. the grammatical modules in ASD, supporting a modular view of the diverse language domains in the language faculty. (shrink)