Literature review The study of humor has a long history, which can date back to Plato (Liu Ping, 2005). Since then, researchers have proposed several theories to account for the emergence of humorous meaning. These include Superiority Theory, Release Theory and Incongruity Theory (Liu Ping,2005). Additionally, researchers have studied humor in different communicative contexts and discourse genres from the perspectives of rhetoric, semantics, pragmatics, sociolinguistics and psycholinguistics. Wang Yong (2001) studies the verbal humor from the perspective of pragmatics, especially from the principles of relevance and found that when the pragmatics analysis is combined with the incongruity theory, we could have a better understanding of how humor is produced and perceived. Zhang Yue (2015) presents a semantic and contextual analysis of verbal humor and concludes that the formation of humorous language depends on the semantic meaning and the context. In order to maximize the humorous effect, users should deal well with the relationship between the semantic and the context levels and apply it flexibly to the pragmatic level. From the above literature, we can see that most researchers have mainly focused on the verbal humor in their studies, which is the major form of humor. In terms of function, verbal humor has the functions of releasing pressure, eliminating embarrassment and improving personal relationship (Tang 2012). Although language is considered as a significant factor that can produce humorous effect, it is not the only one. Other symbolic resources, such as gesture, eye gaze and body movement can also help to create humorous effects. The humor which realized both by verbal and non-verbal humor is called multimodal humor. How does multimodal humor achieve its effects? Attardo, Pickering and Baker (2011) study the prosodic and multimodal markers of humor in conversations and show that a multimodal analysis is crucial, in some cases, for the proper interpretation of the data and that facial expression, as well as laughter, is a significant marker of humor support. Besides, Attardo, Pickering, Lomotey and Menjo (2013) address the issue of multimodal markers of humor in conversational humor and conclude that no differences are found in volume or speech-rate between humorous pause units and non-humorous ones. Besides, pauses are not found to mark humorous turns and smiling is found to mark humor only in the general sense of ”setting the frame” and is not integrated with the humor. Fortanet-G#243;mez and Ruiz-Madrid (2016) analyze two plenary lectures at conferences on linguistics, one in Spanish and the other one in English to explore if there are parallelisms in the humorous elements in each of them. They find that the function of laughter is mainly to draw and keep the attention of the audience, as well as make the content amusing. Chen Qiaoyun and Jiang Guiying (2018) examines multimodal humor through the lens of prototype theory in the framework of conventional incongruity theory of humor. Their research demonstrates that multimodal humor can be accomplished by exploiting the principles of prototype theory, which are prototypicality/non-prototypicality of category members, family resemblance shared by category members and the vague boundary between categories. Abdel-Raheem (2018) tries to discuss humorous political cartoons contingent on pictorial and textual components and discovers that small visual details, such as exaggerated facial expressions, physical characteristics and clothes, can strike many of us as very humorous. There exist some researchers who study humor from the perspective of multimodality. There exist some researchers who study humor from the perspective of multimodality. Villy Tsakona (2009) adopts a General Theory of Verball Humor (GTVH) framework of analysis to show that cartoon humor is not always easy to grasp fully, therefore the reader should pay attention to all the verbal and visual details of each cartoon. Sheng Wenqin (2015) argues that humor is not confined to traditional forms of word play in static way, such as jokes, palm-talks or funny stories,etc; rather it attracts audience in a more modern dynamic art form via audio-visual media. The humors in sitcoms differ from the traditional humors in terms of constitution and transmission. The author makes concrete analyses of Chinese audiences#8217; humor blending in multimodal context, which goes beyond the merely verbal modality to explain the Chinese audiences#8217; cognitive state while feeling a sense of humor in American sitcoms. This research shows that the situational modality contributes the most in the process of Chinese audience#8217;s perception of humors in American sitcoms. Tian Tian (2016) selects famous British sitcom Mr. Bean as an object to study what multimodalities are and analyze the humorous effects produced by representational meaning, interactive meaning and compositional meaning respectively. The author classifies the multimodalities of the sitcom Mr. Bean into three forms, namely, visual form, verbal form and auditory from and finds that visual modalities, such as color, facial expression, gesture and eye-contact, serve as the main forms of modality in Mr. Bean. Zhang Lei (2015) researches the humor in the Ice Age based on the Zhang Delu#8217;s Synthetic Theoretical Framework of Multimodal Discourse Analysis and tries to find out how different modes work together to create humorous effect. He finds that the synergies between visual modes realized by image media and auditory modes realized by linguistic media are the two main modes composing humor in the Ice Age. The synergies between visual modes and auditory modes can be either complementary relation or non-complementary relation. Similarly, Zhang Yanling (2018) investigates how humor is realized in Disney#8217;s animated Zootopia through the interactions of different modes based on Zhang Delu#8217;s theoretical model. The author finds that there are visual mode and auditory mode in Zootopia, of which the visual mode includes elements like facial expression, subtitle, image, gesture and action, while the auditory mode mainly contains verbal language, accent, tone, velocity, various kinds of sound like the sound of vehicles and sound of crunching, background music, etc. All these modes cause humor when they interact with each other . With the introduction of American sitcoms, a growing number of Chinese audiences have been fascinated by them because of their witty dialogues and unique ”American humor” and many researchers begin to study the humor in sitcoms. Signes, Pennock and Franch (1998) study how humor is created in an American series through the analysis of episodes taken from Seinfeld. They draw a conclusion that humor and wit are complex cognitive, social and linguistic phenomena. As a famous American sitcom, The Big Bang Theory has gained much popularity and attracted much attention from researchers both at home and abroad, who has studied humor from the perspective of semantic, pragmatics and Cognitive Linguistics. Zhang Lu (2011) studies the verbal humor in The Big Bang Theory and finds that most of the verbal humor in the sitcom is achieved through violating the four maxims of the cooperative principle, among which the maxim of quantity is the most often violated while the maxim of manner is the least often violated. Similarly, Zhang Chenxia (2016) also studies the verbal humor in The Big Bang Theory from the perspective of pragmatics. She examines the 1350 video clips of verbal humor in the seventh season of The Big Bang Theory from four main verbal humor principle of cooperation, relevance, politeness and presupposition. She classifies the video clips into 8 categories and finds that the violation of the principle of presupposition is used most frequently, followed by the violation of the Tact Maxim and the Generosity Maxim. This is mainly because the violation of the principle of presupposition involves little cultural backgound and therefore most people can understand the humorous effects of unrelated conversations made by interlocutors in two different contexts. Besides, in American sitcoms, although some statements violate the principles of tact and generosity are not polite enough in dialogues, they do create humorous effects that make sudiences laugh. At the same time, the acceptance of impoliteness in the United States is much higher than that in most countries of the world, which leads to the violating the maxim of tact and generosity in American sitcoms. There are other authors who study the humorous language in The Big Bang Theory from the perspective of Cognitive Linguistics. Drawing on the Conceptual Metaphor Theory and Conceptual Integration Theory, Zhang Xue (2012) makes a tentative analysis and discussion of metaphors in The Big Bang Theory to gain a better understanding of the cognitive process of metaphor. Zhang Fan (2013) discusses the classification of the puns in the sitcom and its rhetorical effects which show the rich connotation and the artistic charm. Chen Meiting (2017) uses both qualitative and quantitative methods to analyze representative ironic dialogues in The Big Bang Theory to explore the cognitive mechanism of verbal irony. She discovers that the cognitive process of verbal irony is a cognitive process of resonating and interpreting the prior speaker#8217;s utteranvces. By resonating with what has been told via ironic utterances, the speaker expresses his denial and disapproving attitude and meanwhile creating such contextual effects as sarcasm and humor. Additionally, scholars also investigate humorous language in The Big Bang Theory from the angle of translation. Based on Skopostheorie, Wang Jia (2012) presents a case study of humorous language by analyzing the strategies that translators adopt when translating the humorous language in the sitcom. Guo Yuting and Han Jianghong (2013) applies Juliane House#8217;s translation quality assessment (TQA) model of to analyze and assess the subtitle translation of the wedding scene selected from the 24th episode, 5th season of The Big Bang Theory. They draw a conclusion that the translation corresponds to the source text to a great extent and therefore the quality of the translation is high. As can be seen from the above, most researchers only focus on the verbal humor in the sitcom and few researchers have studied humor from the perspective of multimodality. This thesis tries to bridge this gap by presenting a case study of multimodal humor in The Big Bang Theory from a Cognitive Linguistic perspective.