Based on an analysis of a large group of preposed English finite temporal adverbial clauses (TACs), the present study reveals that a considerable number of them do not serve as a thematic link between preceding discourse and their main clause, which suggests that the characterization of their discourse function on the basis of this link is inadequate. Focusing on their shared role in maintaining the temporal line in narrative discourse, the study proposes to view their use as motivated by an effort to collaborate with the general strategy preferred by language users for comprehending temporal information as suggested by the iconicity assumption, From this point of view, the motivation for using TACs in a preposed position is to override the reader's iconicity assumption by specifying the temporal relationship between the main clause and preceding discourse. Serving this function makes preposed TACs part of the chain of temporal adverbials forming the temporal line of a narrative. In accordance with this understanding of preposed TACs, their postposed counterparts are seen as playing a complementary role they are used in a postposed position when their temporal information is needed without interfering with the temporal line of a narrative. (C) 2010 Elsevier B.V. All rights reserved.
