This thesis presents a longitudinal investigation of spontaneous speech by child Mandarin heritage speakers (n=6, 2;00−5;02) in an English-speaking country with a focus on the acquisition of several syntactic phenomena: wh-questions, object realization, sentence final particles (SFPs) and code-switching. The study on heritage speakers’ languages could contribute to both L1 and L2 language acquisition since they acquire heritage language as L1 and may show some similarities with L2 learners in the acquisition of social majority language. Furthermore, as a type of bilingual that takes place in a specific sociolinguistic environment, their language development could also provide evidence for the debates among bilingual studies and shed more light on input factor. Mandarin and English are chosen to investigate since they are distinct from each other in several domains, which could provide a good testing ground for those hypotheses in language acquisition.
Overall, in child Mandarin heritage speakers’ languages, I only find a little of evidence for the transfer from Mandarin to English and then suggest that it might be owing to the societal environmental language support. Meanwhile, no transfer from English to Mandarin is found, which seems to prove the asymmetry in the direction. I also find that Mandarin heritage speakers use much less code-switching utterances than simultaneous bilinguals (Poeste et al., 2019) and thus suggest that it might be benefited from the relatively monolingual environment the heritage speakers received for each language. The result of this study also contradicts to the Interface Hypotheses (Sorace, 2011), since I find that heritage speakers are able to fully acquire Mandarin null objects and SFPs (e.g. SFP le, ma ne1, ba1 and a), which lie on syntax-semantics-discourse interface. However, these children are found to take longer time than monolinguals to acquire Mandarin wh-questions as well as the SFP ne2, which is in line with previous observations that reduced input in a language lead to a protracted acquisition. Moreover, I notice that they cannot properly use Mandarin SFP ba2 in questions, similar to that of adult Mandarin heritage speakers (Yan, 2020). Thus, I argue that this provides evidence of divergent attainment rather than attrition and agree that this problem is related to the limitation in processing resources (Polinsky and Scontras, 2020).
