Null subjects and null objects in monolingual and bilingual children: a commentary

The occurrence of cross-linguistic influence has been widely attested in the speech of bilingual children at different levels of linguistic description: in phonological, morphological and syntactic domains. One of the most studied grammatical domains is the realization/omission of subjects. Most scholars have looked at the combination of the two null-subject languages Spanish or Italian with the non-null-subject language English. The comparison of the results from these studies with those of other language combinations is revealing and will advance our understanding of cross-linguistic influence. Until now, the focus of these studies has been the null-subject language. Advancing our understanding of cross-linguistic influence requires a detailed analysis of the developmental path taken by the non-null-subject language. Very recent research also highlights the importance of the interaction between grammatical person and overproduction of subject pronouns in the null-subject language. Object omissions ranged among the first grammatical phenomena for which the existence of cross-linguistic influence has been attested. For this grammatical domain, our understanding of the underlying linguistic machinery has advanced during the last decade. While the focus had been on the languages which were (wrongly) assumed not to licence null objects, like French, Italian and English, the fine-grained analysis of null objects in these languages and others has shifted the focus to the question of how children detect the extent to which the adult system allows for null objects. Some language acquisition researchers have assumed a universal null-object stage which is abandoned by the child less quickly if the evidence from the input supports an analysis of the data in terms of such a default grammar. In the bilingual child, this kind of confusing evidence may even be reinforced due to the second language. As in the case of subject omissions, the developmental path in bilingual children