"Grammar, I hate" or "I grammar hate"? L1 and L2 word order differences and bilingual DLD assessment

Cross-module interfaces, such as the syntax-semantics interface, are among the most problematic properties to fully acquire in a second language (L2). First language (L1) monodialectal and bidialectal speakers may show different performances at the interfaces in L2. However, little is known if such a different performance is caused by learners' diverse L1 dialectal backgrounds. The study is motivated by the need to link speech-language pathology and word order typological studies in a bidialectal/bilingual context. The aim is to investigate L1 bidialectism in the L2 syntax-semantics interface acquisition outcome and to separate language difference from language disorder. A sentence-picture matching task on the topic-comment structure was administered among 37 Mandarin monodialectal and 39 Mandarin - Wu bidialectal child speakers. Results of a generalized linear model showed that L1 bidialectals exhibited better syntactic-semantic awareness in L2 than their L1 monodialectal counterparts. The results showed that mono- and bidialectal speakers have different performance patterns at the syntax-semantics interface involving noncanonical word orders for L2. However, the L2 performance was under the impact of language difference between L1 and L2, it does not qualify for Developmental Language Disorder (DLD). Finally, the study offers both theoretical and clinical implications for the diagnosis and assessment of bilingual DLD.