言语交流是人们在社会交往中最常见的沟通方式，用汉语进行言语交流是汉语二语者的学习目标，也是二语习得的重要途径。言语交流包括交流主体、交流内容、交流过程和交流效果等多方面因素，社会认知理论认为言语交流受到学习者内外部因素的共同影响。本文聚焦交流对象这一学习者外部因素，以及话题熟悉度这一学习者内部因素，探讨不同交流对象和话题熟悉度下的汉语二语交流效果及其与交流过程的关系。

研究一采用话题交流任务，从行为层面考察不同交流对象和话题熟悉度下的交流效果。发现汉语二语交流任务能够促进二语学习者口语产出的发展并且影响二语学习者的主观体验，但是不同交流对象和话题熟悉度下的汉语二语交流效果存在差异。客观交流效果上，交流低熟悉度话题时，与母语者交流更能支持二语产出者在句法复杂度和内容维度上的发展。交流高熟悉度话题时，与二语者或与母语者交流都能促进二语产出者句法复杂度和内容维度的提升。词汇复杂度主要受话题熟悉度影响，交流低熟悉度话题更有利于发展口语产出的词汇复杂度。主观交流效果主要受话题熟悉度影响，交流高熟悉度话题的社会愉悦高于交流低熟悉度话题；交流低熟悉度话题的认知负荷高于交流高熟悉度话题。

研究二基于功能性近红外成像（functional near-infrared spectroscopy，fNIRS）超扫描实验，从神经层面上考察言语交流过程中的脑同步模式，发现不同交流对象和话题熟悉度下汉语二语交流过程中的脑同步模式存在差异。（1）无论话题熟悉度为何，在二语产出者右侧额下回和交流对象左侧额下回之间，二语产出者与母语者交流时出现比与二语者交流时更强的脑同步。由于语言优势，母语者在交流中占主导地位，体现在具有时滞效应的脑同步上。（2）无论何种交流对象，当二语产出者在交流中占主导地位时，交流高熟悉度话题时出现比交流低熟悉度话题时更强的脑同步，当二语产出者在交流中处于被主导地位时，交流低熟悉度话题时出现比交流高熟悉度话题时更强的脑同步。可见话题熟悉度影响二语产出者在交流中的地位，进而影响脑同步模式。（3）在二语产出者的前额皮层和交流对象的右侧颞顶联合区发现二语产出者与二语者交流对象交流高熟悉度话题时的脑同步强于其他交流条件，因为在该条件下出现有效的协商互动行为，有利于交流双方相互理解和良好互动关系的建立。（4）不同交流条件下脑同步模式的差异集中体现在“应用”与“分析和评估”两个思维层次上。

研究三从行为和神经两个层面分析不同交流对象和话题熟悉度下的交流效果及其与交流过程的关系，发现不同交流对象和话题熟悉度下的脑同步与交流效果的关系不同。（1）二语产出者右侧额下回和母语者左侧额下回之间产生的脑同步与句法复杂度、句法准确度以及内容维度上的交流效果显著正相关。（2）交流高熟悉度话题不利于语言复杂度的提升，体现为右侧颞顶联合区和交流对象的前额皮层脑同步增加值与语言复杂度显著负相关。（3）无论何种交流对象，交流双方右侧颞顶联合区上的脑同步与二语产出者负面主观体验有关。（4）二语产出者的前额皮层和交流对象的右侧颞顶联合区之间的脑同步与二语产出者口语产出的总体表现和心理努力程度显著正相关。

通过上述三项研究，我们发现不同交流对象和话题熟悉度分别从二语学习者外部和内部共同影响汉语二语言语交流过程，进而影响言语交流效果。首先，从交流对象角度看：（1）不管话题熟悉度为何，二语产出者在语言结构上更依赖母语者，对母语者输出的理解和模仿能促进二语产出者句法复杂度和句法准确度的发展。（2）高熟悉度话题下，二语者之间更容易建立良好的言语互动关系，表现为更有效的协商互动行为，有利于口语产出的总体表现。其次，从话题熟悉度角度看：（1）不管何种交流对象，高熟悉度话题虽有利于相互理解，但受二语产出者自身语言水平限制，不利于语言复杂度发展。但在与二语者交流时，交流高熟悉度话题能引发双方有效的协商互动行为，进而提高二语产出者口语产出的整体表现，但需要更多的心理努力。（2）不管何种交流对象，交流低熟悉度话题时，由于二语产出者缺乏话题相关的内容和语言知识，引起较低的个体愉悦以及更高的任务焦虑和任务难度感知程度。但与母语者交流低熟悉度话题时，母语者语言优势凸显，更能控制交流过程进而帮助二语产出者提高口语产出的总体表现。

本研究为二语教学领域中不同交流对象和话题熟悉度下言语交流任务中资源该如何去优化和匹配提供了实证证据；为言语交流相关的神经研究提供汉语二语方面的证据；并从交流对象、话题熟悉度的角度，探讨外部因素和内部因素在汉语二语交流中的作用，初步构建汉语二语人际言语交流模型，可为汉语作为第二语言的教学与学习提供参考。

Verbal communication is the most common way of communication in social interaction, and verbal communication in Chinese is the learning goal of Chinese second language learners and an important way of second language acquisition. Sociocognitive theory suggests that verbal communication is influenced by both internal and external factors of learners. In this paper, we focus on the external factor of communication object and the internal factor of topic familiarity to explore the effect and formation mechanism of Chinese second language communication under different communication objects and topic familiarity.
In Study 1, a topic communication task was used to examine the communication effects under different communication objects and topic familiarity from the behavioral level. It was found that Chinese second language communication tasks can promote the development of second language learners' oral output and influence their subjective experience, but there are differences in the effectiveness of Chinese second language communication under different communication objects and topic familiarity. Objectively, communication with native speakers objects better supported the development of syntactic complexity and content dimensions of L2 output, especially for low-familiarity topics. Both bilinguals and native speaker communication partners facilitated the development of syntactic complexity and content dimensions in bilingual speakers when communicating about high-familiarity topics. Lexical complexity is mainly affected by topic familiarity, and communicating low-familiarity topics is more conducive to developing the lexical complexity of spoken output. Subjective communication effects were mainly influenced by topic familiarity, and communicating high-familiarity topics was more socially pleasurable than low-familiarity topics; communicating low-familiarity topics had higher cognitive load than high-familiarity topics.
Based on functional near-infrared spectroscopy (fNIRS) hyperscanning experiments, Study 2 investigated the brain synchronization mechanisms during verbal communication at the neural level and found that there were differences in brain synchronization mechanisms during Chinese bilingual communication with different communication partners and topic familiarity. (1) Regardless of the topic familiarity, between the right inferior frontal gyrus of the bilingual outputters and the left inferior frontal gyrus of the native speakers, stronger brain synchronization was observed when the bilingual outputters communicated with the native speakers than with the bilingual speakers. The dominance of native speakers in communication due to linguistic dominance is reflected in brain synchronization with time-lag effects. (2) Regardless of the communication object, stronger brain synchronization emerged when communicating high-familiarity topics than when communicating low-familiarity topics when the bilingual outputter was dominant in the communication, and stronger brain synchronization emerged when communicating low-familiarity topics than when communicating high-familiarity topics when the bilingual outputter was dominant in the communication. It can be seen that topic familiarity affects the position of bilingual speakers in communication, which in turn affects brain synchronization mechanisms. (3) Brain synchronization was found to be stronger in the prefrontal cortex of bilingual speakers and in the right temporoparietal association area of the communicator when the bilingual speaker communicated with the bilingual speaker on topics of high familiarity than in other communication conditions, because effective negotiation and interaction behaviors occurred in this condition, which was conducive to the establishment of mutual understanding and good interaction between the communicators. (4) The differences in brain synchronization mechanisms between the different communication conditions were focused on two levels of thinking: "application" and "analysis and evaluation".
Study 3 analyzed the communication effects and the reasons for the differences between different communication objects and topic familiarity at both behavioral and neural levels, and found that the relationship between brain synchronization and communication effects differed between different communication objects and topic familiarity. (1) Brain synchronization between the right inferior frontal gyrus of bilingual speakers and the left inferior frontal gyrus of native speakers predicted communication effects on syntactic complexity, syntactic accuracy, and content dimensions. (2) Communication of high-familiarity topics is not conducive to language complexity, as evidenced by the negative correlation between increased brain synchrony in the right temporoparietal association area and the prefrontal cortex of the communicator and language complexity. (3) Brain synchronization in the right joint temporoparietal area predicted the negative subjective experience of bilingual speakers, regardless of the subject of communication. (4) Brain synchronization between the prefrontal cortex of the bilingual outputters and the right temporoparietal association area of the communicator predicted the overall performance and mental effort of the oral output of the bilingual outputters.
From the above three studies, we found that different communication objects and topic familiarity jointly influence the process of Chinese second language communication from outside and inside the second language learners, which in turn affects the speech communication effect. First, from the perspective of the communication target: (1) regardless of topic familiarity, L2 learners are more dependent on the native speaker for language structure, and their understanding and imitation of the native speaker's output promotes the development of syntactic complexity and syntactic accuracy of L2 learners. (2) With high topic familiarity, it is easier for bilinguals to establish good verbal interactions with each other, which manifests as more effective negotiated interaction behaviors and facilitates the overall performance of spoken output. Second, from the perspective of topic familiarity: (1) No matter what kind of communication object, although high familiarity topics are good for mutual understanding, they are limited by the bilingual speakers' own language level, which is not conducive to the development of language complexity. However, in the case of bilingual speakers, the exchange of high-familiarity topics can trigger effective negotiation and interaction behaviors between the two parties, which in turn can improve the overall performance of bilingual speakers' oral output, but requires more mental effort. (2) Regardless of the communication partner, communicating low-familiarity topics elicited lower personal pleasure and higher levels of task anxiety and perceived task difficulty due to the lack of topic-related content and linguistic knowledge of the bilingual speakers. However, when communicating with native speakers on low-familiarity topics, the native speaker's linguistic advantage was highlighted, and the native speaker was more able to control the communication process and thus help the second language outputters improve their overall performance on oral output.
This study provides empirical evidence in the field of Chinese language teaching on how to optimize and match resources in speech communication tasks with different communication targets and topic familiarity. It also provides evidence on Chinese as a second language for neurological studies related to speech communication and explores the role of external and internal factors in Chinese as a second language communication from the perspectives of communication targets and topic familiarity. By tentatively constructing an integrated framework of Chinese as a second language communication processes and effects, which can provide a reference for teaching and learning Chinese as a second language.