1. Introduction

This article introduces the concept, classification, and current research status of language transfer, and points out the contributions and shortcomings of generative linguistics and functional linguistics in transfer theory. On this basis, the necessity of constructing a multidimensional dynamic theoretical framework is proposed, aiming to explain and predict the sources, nature, and quantitative changes of language transfer in multilingual acquisition, with the study of bilingual learning of Chinese native speakers as the research object.

2. Previous theoretical explorations of language transfer

In depth exploration of the theoretical basis of language transfer in multilingual acquisition, distinguishing the different meanings of theory, model, and theoretical framework, and emphasizing the innovative importance of theoretical framework in inheriting previous research. From the perspective of generative linguistics, this paper analyzes six transfer models in trilingual acquisition, including the mother tongue factor hypothesis and the second language status model, and points out their one sidedness. Through empirical research and analysis, it has been revealed that the dynamic changes of transfer occur at multiple stages of trilingual development, refuting the view of the type first model. At the same time, a comparison was made between the surgical knife model and the language similarity model, and it was found that the latter was superior in terms of argument rigor and supporting evidence. The exploration of transfer theory from the perspective of functional linguistics involves language level transfer and concept transfer, proposing the "transfer principle of existence" and "transfer principle of absence", as well as the principle of complex adaptive systems. Chinese scholars have proposed three transfer theory frameworks based on foreign research, including the English learning concept transfer framework, the multidimensional dynamic theory framework of language transfer in second language acquisition, and the theoretical framework of concept transfer research, providing new perspectives and analytical tools for understanding transfer phenomena.

3. Major findings on language transfer in multilingual acquisition

Based on the theory of functional linguistics, an empirical study was conducted on the phenomenon of language transfer in multilingual acquisition. The main findings include the sources, nature, direction, and stages of transfer phenomena in the vocabulary and grammar subsystems, as well as the factors that affect transfer. Research has found that in multilingual vocabulary acquisition, second language negative transfer has a greater impact, while mother tongue negative transfer has a smaller impact, and is constrained by language distance and language proficiency. In grammar acquisition, the degree of influence of the mother tongue and second language is not consistent and is related to specific research phenomena. The four important findings are: 1) There are individual differences in the impact of mother tongue and second language on trilingual transfer; 2) Language distance affects transfer, but there is limited evidence on grammar acquisition research; 3) Language proficiency plays a decisive role in the source and quantity of transfer; 4) Research on vocabulary acquisition has also found the reverse transfer effects of context and trilingualism on second language. These findings provide important references for predicting the occurrence patterns of transfer in the process of multilingual acquisition.

4. Multidimensional dynamic theoretical framework for language transfer in multilingual acquisition

A multidimensional dynamic theoretical framework for language transfer in multilingual acquisition has been proposed, abbreviated as the "Multidimensional Dynamic Framework", which is developed based on the second language acquisition transfer theoretical framework proposed by Cai Jinting and Li Jia (2016). The framework focuses on the process of mutual influence and changes among learners' mother tongue, second language, and third language after acquiring them. The framework includes five dimensions: language system, language representation, language transfer, learner factors, and contextual factors, all of which are dynamic, and the dynamics of language transfer are determined by the other four dimensions.

5. Conclusion

A multidimensional dynamic theoretical framework has been proposed, clarifying the five dimensions that affect transfer in multilingual acquisition, emphasizing the dynamic nature of transfer and its performance at different stages. Future research should focus on language similarity, learner subjective similarity, learner and contextual factors, as well as form, semantics, and concept transfer. At the same time, consider the transfer of mother tongue and second language in trilingual acquisition, as well as their reverse transfer. The predictions in this article provide hypotheses for individual and group migration research.