| Nobody would doubt that young children have a better chance than adults to become native-like in second language (L2) acquisition. Such a claim is commonly found in work framed by the Critical Period Hypothesis (Lenneberg, 1967), and many age-related L2 empirical studies confirm the adage "the younger the better." Nevertheless, very little research has investigated whether truly native-like attainment is inevitable when a child is exposed to sustained target language input from very early childhood.; This dissertation aims to demonstrate that some seemingly native-like child L2 learners (L2ers), schooled in the target language for years, are indeed not native-like when engaging in linguistically challenging tasks. In this study, such tasks were created with aural comprehension and oral production of various types of Japanese relative clauses (RCs). Since in Japanese, knowledge of case marking is a prerequisite of knowledge of RCs, two inclusion criteria were applied: (a) at least 80% accuracy on nominative and accusative case marking (in a comprehension task); (b) a native-like conversational proficiency rating (based on a picture-narration task). Of the more than 70 naturalistic child L2ers of Japanese who originally participated, 38 passed (age of onset: 0-7; age at testing: 10 or older). In the main analyses, the RC comprehension and production scores of these 38 child L2ers were compared with age-matched native speakers (n = 17). Group mean comparisons indicated no significant differences between the two groups; however, the child L2 group exhibited substantial within-group variation. Occasionally, some child L2ers, despite ostensible knowledge of Japanese RCs (based on their overall RC comprehension scores), supplied ungrammatical responses in RC production and/or misapplied an RC comprehension strategy from their native language, both of which indicate that these child L2ers are qualitatively different from their native-speaking peers.; The findings suggest that there are indeed some child L2ers who are not truly native-like despite their native-like conversational proficiency, and thus that native-like attainment is not inevitable even when L2ers receive sustained target language input from very early on in life. Other issues discussed include the nature of bilingual acquisition, the difference between knowledge and performance, and pedagogical implications. |
