This study investigates the ultimate grammar state of adult early Tibetan-Chinese bilinguals by examining their interpretation of 'Not-All' SOV sentences in both Tibetan and Chinese. While Tibetan allows both not > ∀ and ∀>not readings in such sentences, Chinese permits only the ∀ > not reading. Using a sentence-picture matching truth value judgment task, we tested 30 bilinguals raised in Tibet who acquired Tibetan at home and Chinese at school. All participants consistently accepted both readings in Tibetan. However, in Chinese, only 13 participants (43.3%) rejected the not > ∀ reading, aligning with monolingual Chinese controls. The remaining 17 (56.7%) accepted both readings, indicating a failure to acquire the native-like constraint despite having native-like Chinese proficiency. These findings suggest that early bilinguals may not always develop fully monolingual-like grammatical systems, even with seemingly native-equivalent proficiency. They also support the argument that monolingual grammars should not serve as the sole benchmark in bilingualism research.
Chen et al. (Fri,) studied this question.