Multidimensionality and determinism of individual differences in -lingualism research: Heritage Language Bilingualism as a case in point

Jason Rothman, UiT The Arctic University of Norway

While there is great conformity in the grammars of speakers of individual languages and a set of variables that underlie how/why this comes to be, there is also a spectrum of individual differences that defines linguistic performance and competence outcomes across all types of speakers (not only bi-/multi-lingual ones, but, yes, L1-dominant users as well). Individual differences are not random. Rather, they are governed by a unique set of dynamic variables we do not quite yet fully understand. The present talk will revolve around two central points falling out from the importance of better understanding the systematicity behind individual differences: (i) the determinism of various internal and external factors—as well as their interactions—contributing to the acquisition and processing of  heritage languages specifically, and thus, by extension language more generally and (ii) questioning the utility, if not appropriateness, of default aggregate comparisons as the norm, especially in bi-multilingual research where particular varieties are too liberally assumed as an appropriate comparative baseline.

While Heritage Language (HL) bilinguals acquire their HLs naturalistically in early childhood, studies over the past three decades not only typically show differences to L1-dominant homeland users, but those that examine/discuss individual level data almost inevitably document high degrees of variation at the individual level. In the present talk, I will present the landscape of HL studies that endeavors to contextualize, investigate and capitalize on the theoretical value of understanding such individual differences—presenting in such a course work that sidesteps the fallacy inherent to monolingual-to-bilingual comparisons for many—but not all—questions currently asked. In doing so, we will discuss “-lingualism” as a scale and, thus, the determinism of context (opportunities for outcomes for a particular type) and why it is (at least partially) explanatory for outcome variation at the individual level for all, but especially for HL bilinguals. Showcasing research from our group with several language pairings, across various age ranges, using a wide array of empirical methodologies and focusing on various domains of grammar—mainly studies from the large 4-year HeLPiNG (Heritage Language Proficiency in their Native Grammars) grant—, we will see that systematicity defines individual difference outcomes in HL acquisition and processing. Yet, as we might expect, there is no one-size-fits-all (set of) variable(s) that is explanatory for everything. Rather, as we should expect, the (weighting and/or interaction of) variables that regress to cover individual differences depend on what (the domain of language), who (the profiles of HL bilinguals) and where (e.g., important differences of location that delimit exposure/usage) we are investigating. This discussion sheds light on multiple levels of trending differences: between so-called monolinguals to HL bilinguals, between distinct populations of HL bilinguals, e.g., European to North American to Asian contexts, and intra-group differences across individual HL bilinguals traditionally studied as a single aggregate.