Overt subjects in English: evidence for the marking of person in an English-Italian bilingual child.

Data from one English-Italian bilingual child (1;10-3;1) are presented in this study which challenge the hypothesis that the consistent realization of overt subjects in English is caused by the emergence of finite verbal morphology in the child's grammar. The argument is made for the emergence of subjects as an independent grammatical property of English, namely the marking of person deixis. Throughout the period of observation there is a significant proportion of overt subjects in the child's English utterances appearing both with finite and non-finite verb forms. Production of subjects stabilizes at 90% of obligatory contexts when no morphological correlates of finiteness have been acquired yet. While subjects are produced at significantly lower rates in Italian, we observe the consolidation of a number of inflected forms marking person agreement. The emergence of overt subjects in English on the one hand, and of subject-verb agreement in Italian on the other suggest that this bilingual child is grammaticalizing the all-important function of person deixis in language-specific ways: the same function is expressed by different forms in the child's two languages.