1. Introduction

This chapter introduces the focus of research on the development of written language complexity in learners, as well as the non-linear developmental patterns observed in this area. It also highlights the lack of attention given to Chinese non-English majors in the study of syntactic and lexical complexity interactions. The chapter sets the stage for the present study, which aims to explore the written language development and interactions between syntactic and lexical complexity of non-English majors in China.

2. Literature Review

This chapter discusses Complex Dynamic Systems Theory (CDST), which has been widely accepted and adopted by researchers and linguists to study dynamic language development. CDST considers the variability and interaction of language subsystems during development, leading to an emphasis on the process of language learning rather than the end result. Variability has been shown to be a key aspect of language development, with intra and inter-individual variation being common. Interaction is also explored, including precursor, supportive, and competitive relationships between different subsystems of language complexity. Overall, more research is needed to understand variability and interactions in the development of written language in the context of Chinese EFL learners, and the current study aims to fill this gap by exploring the development and interaction of syntactic and lexical complexity.

3. Methodology

This chapter discusses the research questions, participants, research measures, data collection and coding, and data analysis. The study aims to investigate the development of English writing complexity in Chinese EFL learners and explores the relationship between syntactic and lexical complexity of learners' written language. The participants were two first-year non-English major students, and measures were taken for syntactic and lexical complexity of their written texts. Data was collected through written homework assignments and analyzed using line graph, moving min-max graph, change-point analysis, and moving correlation to track the developmental trends and examine variability and interaction between syntactic and lexical complexity.

4. Results

This chapter discusses the results of the study, which examined the development of both the syntactic complexity and lexical complexity of the written language and their relationships. The study found that the development of the two participants followed a dynamic and nonlinear mode with varying degrees of variability and both intra-individual and inter-individual differences. It also identified interactions between syntactic complexity and lexical complexity. The min-max graphs illustrated how the participants' syntactic complexity and lexical complexity developed in a nonlinear mode, with variability and fluctuations throughout the study. Results showed that there were differences in the development of the participants' syntactic and lexical complexity, indicating complex dynamics of language. There was a relationship of significant competitive nature between syntactic complexity and lexical complexity for one participant, while the other had an insignificant relationship between the two. The study also found that the interaction between syntactic complexity and lexical complexity shifted from negative to positive, indicating a supportive relationship after a certain point in the study.

5. Discussion

The development of written language in terms of syntactic complexity and lexical complexity was investigated, revealing an increase in MLT and C/T, and a decrease in MLC. Different teaching foci may account for the differences in the results of this study compared to another study. C/T showed a general upward trend, especially evident in Helen, with limited English exposure outside of the classroom. Lexical complexity increased for Jenny but decreased for Helen, differing from another study. The relationship between syntactic complexity and lexical complexity varied between Jenny and Helen, with Jenny showing a consistent competitive dynamic, while Helen transitioned into a supportive relationship. This difference was attributed to the initial language proficiency of the participants.

6. Conclusion

This chapter discussed the dynamic, non-linear, and unpredictable development in both syntactic and lexical complexity for both participants. It emphasized the importance of concurrently examining both syntactic and lexical complexity and suggested that educators employ diverse teaching methods alongside multidimensional assessments. The study also provided inspiration for educators to guide students towards balanced enhancement in every dimension of written language complexity. The chapter recommended extending data collection to more comprehensively investigate written language development, considering language accuracy and fluency from a CDST perspective, and incorporating a broader range of learners from diverse learning contexts in future studies.