Overt subject distribution in early Italian children

It is a well-known fact that children drop subjects from their early sentences. The phenomenon has been well-documented in many languages where this is not permitted in the adult grammar like English, Dutch, German, French (Gerken, 1991; 1996; Radford, 1990; Rizzi, 2000; Bloom, 1990, 1993; Hamann & Plunkett, 1998), but rarely investigated in null subject languages (but see Serratrice, 2002, Serratrice e Sorace, 2003), like Italian, Catalan and Portuguese, except for comparative purposes (Bates, 1976; Hyams, 1986; Valian, 1991; Pizzuto e Caselli, 1992). Cross-linguistic research has shown a great influence of the target language on the early subject omissions: children learning to speak a non-null subject language drop the sentential subject less than children learning to speak a null-subject language. In fact American learners drop subjects less than their Italian peers. Valian (1991) comparing the general percentage of null subjects in a non-pro-drop language, i.e., English, and in a pro-drop language, i.e., Italian, found that subjects are omitted at different rates by learners of the two languages: American English learners show a lower percentage of omission (31% in sentences with MLU < 2.0 and 11% in sentences with MLU 2.0-3.0) than Italian learners (almost 70 %) (see also Valian & Eisenberg, 1996 for a comparison between English and Brazilian Portuguese). These data were used as a reply to Hyams’ (1986) proposal according to which English learners misset the pro-drop parameter assigning a positive value to it. As Valian argued, the different percentages of omission suggest that subject omission in early English and Italian are two distinct phenomena, a line fully developed by Rizzi (1993/4) and supported by the fact that the distribution of early null subjects in Italian and English is different. For example, Italian learners frequently omit subject in finite interrogative clauses (see Guasti, 1996), while English learners do not. Rizzi (1993/4) proposed that early null subjects in early non-pro-drop languages are a root phenomenon, limited to main declarative clauses and governed by a new parameter, the root null subject parameter (Rizzi, 2000). This parameter operates in adult languages and is responsible for subject omission in languages like Levantin Arabic, Brazilian Portuguese (where null subjects are allowed only from main declarative clauses) and is employed by children under processing pressure. Influence of the target language was also confirmed by longitudinal studies with bilingual children who were simultaneously acquiring an overt and a null-subject language. Both Serratrice (2002), who studied an English-Italian bilingual child, and Juan-Garau & Perez-Vidal (2000), who studied an English-Catalan bilingual child, found a great discrepancy in subject dropping depending on the language. Despite these results, a detailed study about the way children learning null subject languages use the sentential subject has not been conducted yet. This study aims at starting to fill this lacuna by looking at early Italian. In particular, we analyze the realization and the distribution of subjects with different classes of verbs (transitive, unergative and unaccusative verbs) and show that children use subjects in different ways depending on the verb class. These findings have two consequences. On the one hand, they show that children distinguish these different classes of verbs and are aware of their different argument structure; on the other, we argue, they shed new light into the debate concerning the acquisition of passives, providing clear evidence that children distinguish between unaccusative and unergative verbs.