Cross-linguistic influence, limited input, or working-memory limitations: The morphosyntax of agreement and concord in Heritage Russian

This study investigated the morphosyntax of adjectival concord in case and number and subject-verb person agreement by monolingual and bilingual speakers of Russian. The main focus of the study is on the potential factors that may trigger divergence between Heritage Language (HL) speakers and those speakers who are dominant in that language, be they monolingual or bilingual. We considered the effects of cross-linguistic influence; limited input (as indexed by Age of Onset of Bilingualism, AOB), and working-memory limitations. An auditory offline grammaticality judgment task was performed by 119 adult participants split into four groups: (1) Monolingual Russian-speaking controls (MonoControl), (2) Immigrant Controls, that is, Russian-Hebrew bilinguals with AOB after the age of 13 (IMMControl); (3) bilinguals with AOB between 5-13 (BL-Late); and (4) bilinguals with AOB before the age of 5 (BL-Early). The latter group represents HL speakers. We did not find effects of cross-linguistic influence or extra memory load; at the same time, the effects of AOB were robust. Additionally, HL speakers (BL-Early group) differed from the other groups in poor performance on adjectival concord, but patterned with the others on person agreement, which indicates that the feature [person] is more robust than other agreement/concord features in HL grammars.