Temporal adverbials as segmentation markers in discourse comprehension

Recent studies have shown that speakers and writers use linguistic devices to signal a shift of topic in their discourse. The present paper considers the comprehension function of one of these segmentation markers, namely a temporal adverbial, by studying its role in a well-established boundary effect: Reading time for the first sentence of a new discourse unit is longer than reading time for the other sentences. In four experiments, participants read short narratives in which: a target sentence was preceded by highly congruent sentences(topic continuity condition) or by weakly congruent sentences (topic shift condition). As predicted by the boundary hypothesis, topic shift sentences were read more-slowly than topic continuous sentences. However. the boundary effect disappeared when the segmentation marker was inserted at the beginning of the topic shift sentence (Experiment 1), though not at its end (Experiment 2). The third experiment showed that not just any adverbial produces this effect. The fourth experiment confirmed that segmentation markers specifically reduce the amount of processing required for the part of the sentence that is topic discontinuous. (C) 2000 Academic Press.