Cross-linguistic influence, or language-internal factors, have been proposed to account for the success/ failure in the acquisition of certain linguistic phenomena in bilinguals based on the properties of the two languages of bilinguals. Yet, it is still an open question whether cross-linguistic influence is triggered solely by language-internal reasons (Hulk, 2017), or alternatively language-external factors (i.e., input characteristics, Age of Onset of Bilingualism, language dominance) moderate the extent of cross-linguistic influence (Rodina et al., 2020; Unsworth et al, 2014).
First, the study investigates cross-linguistic influence (i.e., the influence of the properties of the Societal Language (SL) onto the acquisition of the Heritage Language (HL). Second, the study evaluates language-external factors which might potentially mitigate the effects of cross-linguistic influence in bilinguals.
Three groups of preschoolers were compared on the production of case inflectional morphology in HL-Russian (accusative and genitive cases): 39 Russian-Dutch bilinguals, 36 Russian-Hebrew bilinguals and 41 monolingual Russian-speaking controls. For bilinguals, parental questionnaires provided indices of input characteristics.
The inherent differences between Russian, Hebrew and Dutch enabled us to test the existing models of cross-linguistic influence (e.g., the Full Transfer-Full Access Hypothesis (Schwartz& Sprouse, 1996); the Feature Re-assembly Hypothesis (Lardiere, 2009).
The results showed that HL acquisition is impeded under the influence of the properties of SL which is evident in the lower performance of both bilingual groups as compared to monolingual controls who show a ceiling performance on both tasks. More specifically, the acquisition of morphology is impeded when there are differences in the mapping of the functional features (like in case with Russian-Hebrew bilingualism) and/or the absence of this feature marking (like in case of Russian-Dutch bilinguals). Furthermore, the findings point at the language-external factors (such as input characteristics) and language dominance as important factors driving the strength of the negative effects of cross-linguistic influence.