1. 研究目的与意义（文献综述包含参考文献）

1.introduction1.1 research backgroundstudying oral fluency has become a burgeoning area of research within second language acquisition (sla) and language testing (lt). speech fluency, as we discuss it here, refers to what segalowitz (2010) calls utterance fluency, that is, the ability to produce meaningful strings of linguistic symbols in a largely uninterrupted fashion (gtz, 2013). speaking a second language (l2) is a challenging task for many people. even if second language learners have learned a second language for many years, they at times find themselves speak a second language not so fluently. in previous studies examining oral fluency, fluency measures typically represent the three main dimensions of fluency: breakdown (e.g., different aspects of pausing), speed (e.g., speech rate) and repair (e.g., repetitions and corrections) (gan, 2013; peltonen, 2017). in l2 oral fluency research, pause is a necessary index employed in the measurement of oral fluency in literature (zhao, 2011). very few studies, however, focus on the distribution of pauses in learner l2 oral production. therefore, the present study focuses on the pause position of l2 oral performance. the most probable cause for disfluency is a lack of proficiency, which means speakers do not have sufficient knowledge of the l2 and are out of practice (bergmann, sprenger, et al., 2015). previous l2 fluency studies have predominantly used monologue samples as data to investigate fluency, while less is known about how fluency is maintained in interaction (peltonen, 2017). in addition, several researchers (e.g., segalowitz, 2016; wright ability can be tapped accurately. in addition, pedagogically, a greater understanding of the effect of task type on learner performance will assist teachers in choosing specific task types and conducting task-based instruction to train students language ability. in this way, the oral proficiency of l2 learners can be promoted more effectively. on the other hand, future research may benefit by considering the impact of contextual variables because of different task types on speakers when assessing the oral proficiency of l2 learners.1.3 research purposesthe aim of this study is to investigate the characteristics of pauses in the non-fluent l2 oral production of chinese english learners. thats to say, the study is going to examine how does the pause position of l2 oral performance vary across individual presentation tasks and group interaction tasks. by doing so, the author hopes to provide l2 learners with some practical suggestions to improve their oral performance, and also facilitate the process of designing test tasks.2. literature review2.1 definitions of pausepauses had long been divided into filled and unfilled pauses (fu mead, 2005; ma, 2014). there was some debate about the definition of filled pauses. uh and um were called filled pauses by some researches in contrast to silent pauses (goldman-eisler, 1968). the asumption was that they were pauses (not words) that were filled with sound (not silence).however, it had long been recognized that uh and um were not on a par with silent pauses (clark peltonen, 2017).2.2 related empirical studies on l2 oral performance2.2.1 measures of pausejust as defining pause was rather debatable, the establishment of the measures of pause was not without difficulty, either. pause was mostly studied with the following measures: pause duration, pause frequency and pause position. teixeiraet al. (2012) compared the pause duration in the normal speech and disfluency speech. they concluded that percentages of silence of individuals with disfluencies were much higher compared with those who were more fluent in speech. nevertheless, pause duration was just one parameter of fluency and did not necessarily give much information if considered in isolation from other variables such as speech rate (number of words or syllables spoken per minute) and average length of pauses (the mean number of words or syllables between pauses) (mead, 2005).pause frequency, that is, the number of filled pauses per minute and the number of filled pauses per minute, was also an index frequently investigated by previous researchers. gan (2013) employed the number of filled pauses and silent pauses as one of the measures of fluency. he compared l2 oral performance between individual presentation tasks and group interaction tasks. the conclusion of his study was that the interactive task elicited significantly higher number of filled pauses and unfilled pauses per minute compared with the individual task. however, kormos denes (2004) pointed out that the number of filled and unfilled pauses and other disfluency phenomena were not found to influence perceptions of fluency in their study.pause position was another important measure of pause employed in previous studies. wang et al. (2019) investigated the pause position in three groups of 109 efl learners chinese-english interpreting in paccel-s corpus. the results suggested that pauses mainly occurred before content words (e.g., nouns, verbs, adjectives). gao fan (2011) compared the oral english performance between chinese students and american students. they also analyzed the position where pauses occurred in terms of notional words and function words. the above studies mainly analyzed the position of pauses according to the part of speech of words. but few of them examined pauses in relation to different linguistic (independent clausal, subordinate clausal, phrasal, and atypical) boundaries. moreover, lauttamus, nerbonne, wiersma (2007) pointed out that it was necessary to study the syntactic position of l2 oral pauses. therefore, the present study bridges the gap above by making a comprehensive study of the syntactic pause position of l2 performance in individual presentation task and group interaction task.2.2.2 task-based l2 oral performance a number of studies have concerned with how learner l2 oral performance may vary across different task types. since the present study focuses on two task types, i.e., monologic individual presentation and interactive group discussion, a brief review of a number of empirical studies that compare individual and interactive task performance are presented. foster skehan (1996) studied a narrative task, a personal information exchange task, and a decision-making task regarding their effect on fluency, accuracy, and complexity of learners language performance. the subjects in their study were 32 students studying english as a foreign language at college level. the results indicated that interactive tasks tended to be associated with lower fluency. however, the observation of foster and skehan (1996) did not find support in the study of michel, kuiken, vedder (2007). michel et al. (2007) examined individual (i.e., describing an object) and interactional (i.e., discussing issues with another learner) tasks. they found that students were notably more fluent and made significantly fewer mistake in the dialogic task condition. nevertheless, gan (2013) examined how learner l2 performance regarding accuracy, fluency and complexity may vary across two different task types and suggested a trend in the direction of less fluency being associated with interactive tasks.2.3 problems in the previous studiesthe above studies that compare individual and interactive task performance draw mixed conclusions. given this, any claims concerning types of tasks and l2 performance need further confirmation. besides, most of the studies mentioned above investigate the effect of different task types on learner performance from the perspective of fluency in a broad sense whereas few of them focus specifically on pause position, which is an important measure of oral fluency. therefore, this study aims at filling the gap by investigating how learners oral performance in terms of pause position may vary across individual task and interactive task.referencesbachman, l., palmer, a. (1996). language testing in practice. oxford: oxford university press.bergmann, c., sprenger, s., schmid, m. (2015). the impact of language co-activation on l1 and l2 speech fluency. acta psychologica, 161, 25-35.clark, h. h., tree, j. e. f. (2002). using uh and um in spontaneous speaking. cognition, 84, 73-111.foster, p., skehan, p. (1996). the influence of planning time and task type on second language performance. studies in second language acquisition, 18, 299-323.goldman-eisler, f. (1968). psycholinguistics: experiments in spontaneous speech. new york: academic press.gtz, s. (2013). fluency in native and nonnative english speech. amsterdam: john benjamins.gan, z. d. (2013). tasktypeandlinguisticperformancein school-based assessment situation. linguistics and education, 24, 535-544.kormos, d., denes, m. (2004). exploring measures and perceptions of fluency in the speech of second language learners. system, 32, 145-164.lee, j. et al. (2019). language planning and pauses in story retell: evidence from aging and parkinsons disease. journal of communication disorders, 79, 1-10. lauttamus, t., nerbonne, j., wiersma, w. (2007). filled pauses as evidence of l2 proficiency: finnish australians speaking english. sky journal of linguistics, 20, 273 -307.mead, p. (2005). methodological issues in the study of interpreters fluency. in a. riccardi, m. viezzi (eds.), the interpreters newsletter (pp. 39-63). michel, m., kuiken, f., 以paccel-s语料库为例，《山东外语教学》，37（2）：94-103。

高莹、樊宇（2011），基于语料库的中美大学生口语叙述中停顿现象比较研究，《解放军外国语学院学报》，34（4）：71-75。

缪海燕（2009），第二语言口语非流利产出的停顿研究，《解放军外国语学院学报》，32（4）：56-60。

2. 研究的基本内容、问题解决措施及方案

Research methodology2.1 Research questions The present study investigates how learner L2 oral pauses vary across individual presentation task and group interaction task. The specific research questions are as follows:1.What are the characteristics of pause position of L2 oral performance in individual presentation task?2.What are the characteristics of pause position of L2 oral performance in group interaction task?3.How does pause position of L2 oral performance vary across individual presentation task and group interaction task?2.2. SubjectsThe subjects of the study comprise 29 students, both males and females, from a natural class. They are all sophomore students ranging in age from 20 to 25, studying English as a foreign language at the department of foreign languages and literature of a science and technical university in Nanjing. The participants have studied English at school for more than 8 years.2.3 InstrumentsTest for English Majors Band Four (TEM-4) is a standardized test for English majors in China. This test is effective in measuring the English proficiency of English majors. TEM-4 oral test is used as the instrument of this study. The oral English test in TEM-4 includes three types of assessment task: talking, role-play and retelling. The task of talking is employed as the instrument of individual presentation task in this study and the task of role-play is chosen as the material of group interaction task.2.3.1 Individual presentation taskIn the individual presentation task, participants are asked to describe an unforgettable personal experience they have before in English. They are required to present some ideas or information over the topic individually without interruption. They have three minutes to prepare and three minutes to speak. 2.3.2 Group interaction taskA paired task are administrated to provide the participants with a communicative context. Data are obtained not from learner-native or learner-interviewer speaker interaction, but from learner-learner interaction. It is believed that peer interaction would represent a context that learners could possibly encounter in the real world (Bachman Palmer, 1996). In the current study, participants are asked to express their opinions on an issue in English. They are first given a short description of an issue about a whether it is necessary to offer a compulsory mental health course. Preceded by three minutes of planning time, the dialogue task is completed in pairs in a quiet space. The subjects have four minutes to complete the task.2.4 Data collectionSpeech samples are collected in a classroom where computers and headsets are available to all subjects. The first one and a half minutes of the individual task samples and the first three minutes of the interactive task samples are used. For the analysis of pauses, all data are transcribed and processed by using the PRAAT software (Lee, Huber, Jenkins, Fredrick, 2019). The beginning and end of each speech segment is determined first by using the PRAAT function To textgrid (silences) in order to find pauses. All pause boundaries are checked and adjusted manually by the transcriber by visually inspecting the spectrogram and waveform and listening to the recording. Unfilled pauses in this paper refer to the intermissions in sentences or between sentences lasting 0.3s or longer, as in a number of earlier studies (e.g., Miao, 2009; Ma, 2014; Raupach, 1987). This means that pauses shorter than 0.3 seconds are considered to signify breathing and articulation, and are not identified as pause. Filled pauses in the present study are defined as pauses (not words) that are filled with sound (not silence) such as er, uh and um, as in many previous studies (e.g., Fu Wang, 2016).