A Dynamic Systems Study On The Development Of Lexical Complexity And Syntactic Complexity In L2 Writing Of Higher Vocational College Students

Second language(L2)writing has always been an important research direction in the field of second language acquisition(SLA),and lexical complexity and syntactic complexity are two important indicators in L2 writing research.Dynamic Systems Theory(DST)regards language as a complex system that is constantly developing,and various subsystems are interconnected and the development of a single subsystem cannot represent the development of the whole second language.Therefore,in the study of L2 writing,attention should be paid to the joint development of vocabulary and syntax.Since the introduction of DST,more and more empirical studies have explored the dynamic development of lexical complexity and syntactic complexity.Nevertheless,few studies have taken higher vocational students as the research subjects to examine the developmental patterns of vocabulary and syntax,and the interactions between the two subsystems.With seventeen non-English majors of higher vocational college as the overall research subjects,one academic year’s tracking experiment of lexical complexity and syntactic complexity in English writings was conducted from the perspective of DST.The subjects were asked to write argumentative essays for eight times,and a total of 136 research corpora were collected.Then,the highest-score student and the lowest-score student were selected as the individual research subjects,which was based on the average scores of eight writing scores.And three measurement indices of lexical complexity were chosen to measure lexical density,lexical sophistication and lexical diversity respectively.Three measurement indices of syntactic complexity were employed to measure sentential complexity,clausal subordination and phrasal sophistication separately.The current study addresses the following four questions:(1)How does the lexical complexity of higher vocational college students develop over one academic year’s writing practice at group level?(2)How does the syntactic complexity of higher vocational college students develop over one academic year’s writing practice at group level?(3)What are the developmental features of lexical complexity and syntactic complexity of the highest-score student and the lowest-score student over one academic year’s writing practice?(4)What are the interactive features between lexical complexity and syntactic complexity,in terms of group level and individual level over one academic year?Four major findings are obtained:(1)during one academic year,higher vocational college students present nonlinear development trends in lexical complexity at group level.In detail,lexical sophistication and lexical diversity show an upward trend,while lexical density indicates a trend of ascending and then descending.(2)Syntactic complexity at group level also presents nonlinear development trends.Specially,sentential complexity and phrasal sophistication demonstrate a downward trend,while clausal subordination displays a trend of ascending and then descending.(3)The highest-score student and the lowest-score student show a significant upward trend in sentential complexity and lexical diversity respectively.According to the qualitative analysis,the dynamic changes in lexical complexity and syntactic complexity of the individuals are affected by teaching contents,topic familiarity,motivation,writing time points,language proficiency and personality.(4)Group level and individual level demonstrate different interactive features between lexical complexity and syntactic complexity.There is a significant negative correlation between lexical diversity and sentential complexity at group level.In the interactions at individual level,lexical density and clausal subordination have a significant negative correlation in the lowest-score student’s writings.And lexical density of the highest-score student shows a significant negative correlation with clausal subordination whereas lexical density presents a significant positive correlation with phrasal sophistication.The study has practical significance for L2 writing teaching of higher vocational college students.Teachers can provide timely teaching interventions according to the development of students’ lexical complexity and syntactic complexity at different stages.Meanwhile,teachers can guide students to increase language input to enlarge vocabulary and improve the use of advanced words,subordinate clauses and complex phrases.Furthermore,higher vocational college students also need to improve learning motivation and actively cooperate with their teachers to do more writing exercises.