The Role of Visual Aids and Topic in Shaping Theme–Rheme Organization and Thematic Progression: A Comparative Study of TED Talks

This study investigates the relationship between visual aids, topic, and thematic organization in TED Talks within the framework of Systemic Functional Linguistics (SFL). More specifically, it examines how the presence of visual support and variation in subject matter may influence Theme–Rheme organization and thematic progression in spoken public discourse. The corpus consists of three TED Talks. Forget the Pecking Order at Work by Margaret Heffernan is delivered without visual aids, whereas Let’s Prepare for Our New Climate by Vicki Arroyo and How Buildings Can Improve Life Inside and Out by Doris Sung make use of visual support and address environmental and architectural topics, respectively. This comparative design addresses two main questions: whether the presence of visual aids is associated with differences in Theme–Rheme organization and thematic progression, and whether talks from different subject areas exhibit distinct thematic patterns when visual support is present. Drawing primarily on Halliday’s account of Theme and Rheme and established models of thematic progression, the talks are analyzed at clause level. Ranking and embedded clauses are distinguished, and each ranking clause is manually coded according to its topical, textual, and interpersonal Themes, the markedness of its topical Theme, and its thematic progression pattern. Quantitative comparison is combined with qualitative interpretation to identify recurrent tendencies, similarities, and differences across the three talks. The analysis indicates that both visual support and topic are associated with variation in thematic organization. The talk delivered without visual aids relies more heavily on verbal resources to establish continuity and guide the audience through the discourse. By contrast, the visually supported talks show greater use of Themes connected to the immediate presentation context, including demonstrative, locative, and audience-oriented points of departure. Differences are also observed between the two visually supported talks. The environmental presentation displays a comparatively explanatory and information-focused organization, whereas the architectural presentation adopts a more demonstrative and audience-oriented structure, reflecting its emphasis on presenting designs, materials, and technological applications. The study contributes to research on the textual organization of spoken public discourse by showing how visual support and subject matter may influence thematic choices and information development in TED Talks. It also highlights the value of Theme–Rheme and thematic progression analysis for explaining how speakers establish coherence, organize information, and guide audiences through complex ideas.