A Longitudinal Study On Lexical Complexity Development Of Second Language Learners’ Written English

Based on Complex Dynamic Systems Theory,this research studied the compositions of 24 first-year non-English majors in a university in Northeast China and explored the lexical complexity development of written English from ten measurement indicators in three dimensions,namely,lexical density,lexical sophistication,and lexical variation.The reasons for these changes were delved into as well.Results are as follows.After two semesters of English learning,(1)lexical density in second language learners’ written English presented a dynamic and non-linear change.On the whole,after writing practices,lexical density had been significantly improved,which is due to the learners’ increasing engagement in English learning and genre difference of their writings.Additionally,lexical density of argumentative essays was significantly higher than that of narrative ones.(2)The development of lexical sophistication in their writings also fluctuated,with peaks and troughs.Verb sophistication had no obvious change,and the learners rarely used complex verbs in writing.(3)The lexical variation development of the learners’ written English was also a dynamic process.Among the seven indicators for measuring lexical variation,the development of noun variation was more salient.Lexical variation in argumentative essays was not significantly different from that in narrative essays.Theoretically,this study verifies the dynamic and nonlinear characteristics of the development of lexical complexity,enriches the research results of English writing,and provides empirical data for Complex Dynamic Systems Theory.Pedagogically,the results of this research can help college English teachers to design writing tasks and teaching procedures more appropriately,and to guide students to pay attention to the use of vocabulary in the writing process,so as to promote the development of second language learners’ English writing ability.