Effects Of Task Complexity On Chinese High School EFL Learner’s Argumentative Writing

Task-based language teaching has been widely accepted since 1980 s which is based on the importance of output hypotheses in favor of language learning. The research of task complexity, as an important part of it, is also popular in the field of second language acquisition. Accuracy, fluency and complexity are three indices of measuring second language level.The research is based on the Robinson’s theory on task complexity, also introducing two models on attentional resource, Cognitive Hypothesis and Limited Attentional Capacity Model. The former asserts that attentional resource is multi-dimension, and with the increasing of task complexity, the complex task produces better effects and accuracy won‘t be traded off by complexity, while the latter maintains that there exist trade-off effects among the three aspects of language production. With the rising trend of task complexity, learners have poor performance.The thesis made a study with quantitative analysis method, involving 60 participants, high school students in grade three, into the task testing. What attempts to obtain from the present study is the overall description of the effects of task complexity on written production in terms of accuracy, complexity and fluency. They are divided into three groups and not given the same pre-task planning time or the same amount of writing assistance. In Task 1, 10 minutes of planning time and prior knowledge are provided. Besides, the writing assistance is only provided in Task 1 and Task 2. In Task 3 there is no prior knowledge and planning time are provided. The researcher adopts the ratio of error-free clause, words per T-unit word types per square root of two times the words, clause per T-unit to measure accuracy, fluency, lexical complexity and syntactic complexity.After all the procedures have been done, the data are analyzed by SPSS 17.0. The results show that with task complexity increasing, learners produced less accurate, more grammatical complexity and less lexical complexity, while no significant difference was found in fluency from the group statistics, whereas task complexity had a positive effect on fluency from the individual analysis. In addition, with regard to two aspects of the complexity, there is trade-off effect between grammatical complexity and lexical complexity. To some extent, the results lend support to Skehan’s model which asserts that there are trade-off effects among the three aspects of language production with respect to limited attentional resources. Even trade-off effects exist in the same dimension of complexity.Based on the findings, some pedagogical implications for task design and task-based instruction are drawn. Individual difference teachers should be taken into consideration when choosing proper task complexity to make sure students could improve themselves gradually. It is also hoped that the present study may be of some help for the future quantitative written production research.