The role of temporal segmentation markers in discourse processing 1

Recent studies have shown that temporal expressions like around two o'clock and then are used by speakers and writers to signal thematic shift, and that and is used to signal continuity in narratives. The present paper focuses on the comprehension function of these markers. The role of the markers was investigated by measuring the availability of words from the preceding text. Results from three experiments suggest that temporal markers modify the availability of preceding words. Segmentation markers like around two o'clock and then reduce this availability while continuity markers like and improve this availability. These results are compatible with the hypothesis that segmentation markers lead readers to not integrate new information with preceding information, but to put the new information into a separate structure. In the last ten years, corpus analysis and experimental research showed that speakers and writers exploit devices like punctuation, referential expressions, and temporal expressions to highlight theme shifts in discourse (Bestgen, 1992; Bestgen & Costermans, 1994; Costermans & Bestgen, 1991; Fayol & Abdi, 1988; Peterson & McCabe, 1991; Segal, Duchan, & Scott, 1991; Vonk, Hustinx, & Simons, 1992). It is generally postulated that these segmentation markers should keep listeners and readers from trying to relate the new incoming information to the preceding information. Do they really help readers and how? After describing some temporal expressions used by speakers and writers to signal the segmentation of their discourse, the present report will focus on the role of these temporal segmentation markers during the comprehension of text. 1 Yves Bestgen is supported by the Belgian Fund for Scientific Research. 2 Version finale dans Discourse Processes, 19 , 385-406. Temporal markers of segmentation The linguistic devices used by speakers and writers to express temporal relation between successive actions or events have been the subject of a large number of linguistic and psycholinguistic studies. These studies have shown that the simplest way for the speaker or the writer to accomplish this task is to express two subsequent actions in two juxtaposed sentences: "I woke up. I had breakfast. " Since Reichenbach's (1947) seminal work, a number of writers have quoted this strategy as the default process. This simple strategy implicitly indicates that the second event follows the first (Dowty, 1986; Hinrichs, 1986; Partee, 1984). The strategy can be modulated to highlight the continuity or the discontinuity of actions or events by introducing a connective between the two sentences (Fayol, 1986; Segal et al., 1991). For continuity, the preferred connective is the asymmetrical and (Lakoff, 1971). For discontinuity, people prefer to use then, next , or afterwards. These devices place the second (new) event in relation to the preceding one by using an intrinsic time scale that is internal to the narrative. However, they give only partial information about the temporal organization of the narrative since the amount of time spent in each action must be determined by context (Moens & Steedman, 1988). Speakers and writers can improve on this by using an absolute reference framework, indicating explicitly the time of the day when an action started (e.g., around 10 o'clock). Following Ehrich and Koster's analysis of spatial marker in description (1983), Costermans and Bestgen (1991) called this kind of temporal indication an anchorage marker because it anchors the starting time of an action in an absolute time scale external to the narrative. In some sense, it gives a synchronization signal to the addressee. Concentrating on simple narratives about daily events, Costermans and Bestgen (1991) have argued in favor of the discourse structuring function of these temporal expressions. In a corpus analysis of forty daily events, they observed that speakers introduced anchorage markers and temporal adverbs when there was a theme shift in the activities, but that speakers in cases of high continuity either did not use any specific device or used and. These observations were extended and confirmed in experimental studies in which subjects were given the gist of narratives that they had to communicate either orally or in writing (Bestgen, 1992; Bestgen & Costermans, 1994; Costermans & Bestgen, 1991). For instance, Bestgen (1992) analyzed the development of the child's capacity to organize discourse both cognitively and linguistically. Children of six, eight, and eleven years old, as well as adults, had to transform a series of pictures into a story. Later in a metacognitive task, these subjects were asked to describe the structure perceived in the content of the narrative. Results indicated that children as young as eight express the hierarchical structure of a narrative by means of the different classes of temporal markers presented above. The functional organization of these four temporal devices (i.e., the anchorage marker, then and other temporal adverbs, no temporal expression, and and) is Temporal markers of discourse structure 3 summarized in Figure 1. The vertical dimension displays the strength with which they highlight the (dis)continuity in narratives. And marks high continuity between the actions or events described in two sentences. Then marks discontinuity. The anchorage marker signals high discontinuity.