Individual Differences in Bilingual Child Language Acquisition: A plunge into a Complex and Dynamic Network.

Large individual differences in language skills are well documented in monolingual children (e.g., Kidd, Donnelly & Christiansen, 2018). In bilinguals, the broad variation is even more pronounced. Interestingly, some bilingual children might be weak in their Heritage Language (HL, also labeled as Minority Language, Home Language, Community Language), to which they have naturalistic exposure from birth. Others might be weak in their Societal Language (SL), the language of the surrounding and educational environment. Large individual differences are observed in neurotypical bilingually exposed children as well as in their bilingually raised peers with developmental language disorder, autism spectrum disorder, and hearing impairment (see also Armon-Lotem & Meir, 2016; Meir & Novogrodsky, 2020). Figure 1 visualizes individual differences in morphosyntactic skills of monolingual and bilingual children with typical language development aged 5;5-6;8 as indexed by the LITMUS Sentence Repetition tasks (the data are drawn from Armon-Lotem & Meir, 2016; Meir, 2018). While monolingual preschool children (MonoRU and MonoHE) show little variation, bilinguals with different levels of dominance (balanced bilinguals: BB; HL dominant: HL-D; SL dominant: SL-D) as determined by standardized tests exhibit large individual differences within each language and across their two languages.