Processing DOM in relative clauses Salience and optionality in early and late bilinguals

Early heritage bilinguals have been repeatedly found to differ from late bilinguals and from monolinguals (e.g., Montrul, 2008, 2011). In the realm of Spanish Differential Object Marking (DOM), both early heritage bilinguals (Montrul et al., 2015) and late bilinguals (e.g., Bowles & Montrul, 2008; Guijarro-Fuentes, 2012) exhibit difficulties. DOM in a complex structure such as relative clauses (RCs) provides an ideal setting to differentiate early from late bilinguals, but it has only been explored offline (Perpinan & Moreno-Villar, 2013). This study fills this gap by examining the role of word order (SVO, OSV, OVS), optionality (obligatory vs. optional contexts), and saliency (bound vs. unbound morphology) on the processing of DOM in embedded RCs in Spanish, by Spanish monolinguals, and advanced early heritage and late bilinguals of Spanish. The results of a word-by-word non-cumulative self-paced reading task revealed that all participants were more accurate but were slower in subject than object RCs, and in OSV than OVS RCs. Slower RTs in subject RCs were due to the presence of DOM, and in OSV to interpreting OVS as SVO. Also, all participants were both more accurate as well as faster in obligatory than optional DOM, unbound than bound morphology, and masculine than feminine RC NPs. These findings reveal that processing difficulties in RCs result from the interaction of word order and DOM, and that processing DOM depends on both salience and, to a lesser extent, gender. Finally, this study shows that early heritage bilinguals are closer to monolinguals than late bilinguals in terms of morphosyntactic processing patterns.