First language (L1) maintenance in typologically close languages: The role of second language (L2) exposure and L2 performance

The present study contributes to the growing body of research showing absence of first language (L1) attrition when the L1 and second language (L2) are structurally aligned and regularly used. It investigates possible language attrition in the morphosyntactic features of 3rd-person Italian accusative clitics across three clitic structures in sequential L1-Italian–L2-Spanish speakers immersed in a Spanish-predominant environment. A total of 19 Italian–Spanish bilinguals and 18 Italian monolinguals completed a structural priming task to assess knowledge of clitic form and placement in spoken production. In the data analysis, key variables such as L2 exposure or L2 performance were also considered. We hypothesise that bilinguals will not exhibit significant variation in clitic form and placement compared to monolinguals due to the combination of continued L1 use and complete structural overlap between Italian and Spanish. However, syntactic complexity, particularly in modal constructions, was expected to influence placement and form in both groups due to processing demands. The results supported our predictions, revealing no significant differences between bilinguals and monolinguals in clitic accuracy, and lower structural accuracy in modal structures compared to lexical or causative structures in both groups. Although the present design does not allow us to isolate the mechanisms responsible for L1 maintenance, our findings offer empirical evidence that structural overlap and ongoing L1 activation can preserve grammatical stability even under intense L2 exposure.