A Case Study On The Lexical Complexity Development Of College Students’ English Written Language Based On Dynamic Systems Theory

Lexical complexity is the criteria of vocabulary level and the indicator of English writing proficiency.In recent years,a large body of empirical studies of lexical complexity at home and abroad mainly spend more attentions on the general lexical complexity development and influencing factors,while limited research has been conducted on development characteristics of individual written lexical complexity,let alone research on the interaction between different indices of lexical complexity between the learners with different performance levels.Therefore,from the angle of Dynamic Systems Theory(DST),the current study seeks to explore the dynamic interaction of the three measurements of lexical complexity development of college English learners’ written language among lexical sophistication,lexical density and lexical diversity.Four non-English-major college students from a prestigious university in Yunnan are recruited as the sample of the study.Sixty-four compositions were collected in the course of four months and were processed by Vocab Profile software.Adopting SPSS22.0 software and Excel analyzes statistically the three measurements of lexical complexity.These three indices,Academic Word List(AWL),Content Word Ratio(CWR)and Uber index(U)were respectively used to measure lexical sophistication,lexical density and lexical diversity.And this study visualizes the development trajectories and characteristics of learners’ lexical complexity through the moving min-max graph,and probes to the dynamic interactions among three measurements of lexical complexity.This study yields the following findings: 1)The lexical complexity development of non-English-major college students’ written language exists a dynamic upward development trajectory in terms of three indices of lexical complexity in general.I n English learning,there present iterative fluctuations and oscillations over time.The inter-individual and intra-individual variability of lexical complexity are found in the current study.Moreover,the degree of variability is various among non-English-major college students.The degree of variability in lexical sophistication and lexical diversity is stronger compared to lexical density.2)As for the dynamic interaction among the three measurements of lexical complexity in L2 writings,a positive interaction between lexical density and lexical diversity is found,while a competitive interaction between lexical sophistication and lexical diversity,lexical sophistication and lexical density is generated for non-English-major college students with intermediate-high level.As for the intermediate levels,there exists a positive interaction between lexical sophistication and lexical density,lexical density and lexical diversity,while a competitive interaction between lexical sophistication and lexical diversity is found over time.The current study draws the findings and implications as follows: language is a dynamic system and language development is a process with non-linearity and dynamics.There exist inter-individual and intra-individual variability in lexical complexity development for non-English-major college students’ written language.The variability could be influenced by learners’ initial conditions,internal and external resources.Supportive and competitive dynamic interactions between three subsystems of lexical complexity are found over time.The study sheds light on pedagogical and methodology implications in L2 writing.College English teachers should provide writing scaffolds and timely feedback to improve college students ’English writing levels in the forms of diverse methods of teaching evaluation.