A Study On The Impact Of Writing Prompts In High-stakes Tests On Learners' English Writing Performance

Task-based language testing has caught great attention since the late 1990 s.Since then,many researchers have begun to have interests in making in-depth research in task-based language testing.The research about task difficulty and task types in language testing is abundant,but the deep study on task condition and its impact on task quality is scant.Based on Skehan's model of test performance,this thesis studies the influences of four writing prompts(a Chinese outline prompt,a picture prompt,a chart prompt and a situation prompt)on learners' writing performance.It investigates the effects of prompt characteristics on learners' writing production in terms of lexical diversity,cohesion and coherence,syntactic complexity and readability.The research questions are:1)Do prompt types influence students' writing performance?2)Do prompt characteristics influence the textual features of students' essays?3)What are the predictive powers of learners' English writing performance?The participants of the present study were 60 undergraduate English majors in a college.We collected their compositions of four writing tasks as the corpus for analysis.They were required to finish four compositions from week one to week four in September 2016.The compositions were evaluated by three experienced raters according to a 5-scale scoring rubric with the full score of 15.The textual features of their compositions were analyzed through Coh-Metrix 3.0 in terms of descriptive features,lexical diversity,cohesion and coherence,syntactic complexity and readability,and the data were analyzed with the help of SPSS 16.0.Data analysis reveals that:1)Prompt characteristics influence students' writing quality in general.The mean scores are significantly higher in writing task one(a Chinese outline prompt)than the other three tasks(p=.000).The students get the lowest grades in writing task three(a chart prompt).The reason may be that students get abundant training since senior high school in the writing tasks with Chinese prompts.They find a chart prompt more difficult,because a chart prompt provides the test takers with little text information.2)Prompt characteristics affect the textual features of learners' writing.Promptfeatures have significant effects on the essay length of writing production.Texts in task four(a situation prompt)are longer than the other three texts.For lexical diversity and syntactic complexity,texts of picture prompt and situation prompt show more complicated features.3)The predictive powers of learners' writing performance include paragraph count,sentence count,word count(p=0.000)in four writing tasks.Writing long is an important indicator of language proficiency.These three factors combined can explain52.7% of the variance in the evaluation of compositions in writing task one.Six factors(paragraph count,sentence count,word count,type token-ratio of all words,incidence of connectives,incidence of adverbial and contrastive connectives)combined can account for 62.7%(r2=0.627)of students' performance in writing task two.Five factors(paragraph count,sentence count,word count,type-token ratio of all words,mean of stem overlap and the number of modifiers per noun phrase)in writing task three can explain 50.8% of students' writing performance.Seven influential factors(paragraph count,sentence count,word count,lexical diversity,number of modifiers per noun phrase and readability)can explain 74.3%(r2=0.743)of students' writing performance in writing task four.Based on the findings,some implications are proposed to develop language testing and cultivate learners' writing proficiency.1)Writing prompts in high-stakes tests should be diversified to examine students' individuality and creativity.Prompts in Chinese may lead students to translate the Chinese specifications into English without developing their potential writing abilities.2)Test designers should be aware of the effect of writing prompts on the test takers' writing performance.Pretest of different writing prompts is necessary to ensure the test validity.3)Instructors should cultivate students writing abilities with diverse prompts during language teaching.