Compensating for processing difficulty in discourse: Effect of parallelism in contrastive relations

This study aims to establish whether the processing of different connectives (and, but) and different coherence relations (addition, contrast) can be modulated by a structural feature of the connected segments, namely parallelism. While but is mainly used to contrast two expressions, and occurs in many different relations and has been shown to come with a processing cost. We report three self-paced reading experiments in which we manipulate whether the connected segments share a common verb phrase. Such parallel constructions frequently occur in contrastive relations, although they are typically treated as additive in comprehension research. We expect that parallelism will compensate for the cognitive complexity of contrast and for the ambiguity of and, by further signalling the coherence relation. Our results indicate that parallelism speeds up processing, and provide further evidence for priming in comprehension. However, parallelism interacted with connective ambiguity in an overt disambiguation task (Experiment 3), but not in a more natural reading task (Experiment 2). We argue that the processing of contrast remains shallow unless disambiguation is explicitly required.