We report the results of two studies that investigate the factors contributing to non-native-like ability in child and adult heritage speakers by focusing on oral production of Differential Object Marking (DOM), the overt morphological marking of animate direct objects in Spanish. In study 1, 39 school-age bilingual children (ages 6-17) from the…

The fundamental difference hypothesis (FDH), as formulated by Bley-Vroman (1990), claims that SLA tends to be nonconvergent because domain-specific linguistic mechanisms available in early childhood cannot be used for language learning in adulthood: Instead, second language (L2) learners deploy domain-general problem solving skills. I claim that…

This study compares the linguistic knowledge of adult second language (L2) learners, who learned the L2 after puberty, with the potentially "eroded" first language (L1) grammars of adult early bilinguals who were exposed to the target language since birth and learned the other language simultaneously, or early in childhood (before age 5). I make…