In this talk, I provide an overview of two decades of my research in the field of bilingualism, focusing on the effects that learning of a new language (L2) has on the first language (L1). Learning a new language often comes at a price of losing some control over the first language. My research on language loss, attrition, or forgetting in children and adults has produced unique findings that are often difficult to replicate within the limitations of experimental settings. One of those studies was done on a Russian adoptee in the U.S (Isurin, 2000). The correlation between the rate of L1 forgetting and L2 acquisition and the suggested semantic overlap responsible for the loss of vocabulary were further tested in a simulated experimental study (Isurin & McDonald, 2001). The likelihood of losing access to L1 lexical items for which one acquires a translation equivalent in L2 was supported by both studies. L1 loss, however, does not necessarily concern such extreme situations as linguistic isolation in case of young international adoptees. It can happen to any adult living in the L2 environment. Here, findings in difficulties with lexical access (Isurin, 2012), morphosyntactic changes (Isurin, 2007) or choice of lexical terms to express belonging (Isurin, 2011) were registered in Russian immigrants residing in the U.S., Israel, and Germany and having three different languages affecting their L1.
These psycholinguistic considerations tie with my sociolinguistic work, where I looked at the inherent link between bilingualism and identity in immigrants who came to a new country as children, adolescents or adults (Isurin, 2011, 2015; Isurin, Furman, & White, 2015; Isurin, 2017). Self-reported perception of identity loss due to immigration and subsequent bilingualism and reported attitudes to language maintenance in younger generation provide fascinating narratives that elucidate the statistical data.