Spoken contributions in dialogue often continue or complete earlier contributions by either the same or a different speaker. These compound contributions (CCs) thus provide a natural context for investigations of incremental processing in dialogue.We present a corpus study which confirms that CCs are a key dialogue phenomenon: almost 20% of contributions fit our general definition of CCs, with nearly 3% being the cross-person case most often studied. The results suggest that processing is word-by-word incremental, as splits can occur within syntactic ‘constituents’; however, some systematic differences between same- and cross-person cases indicate important dialogue-specific pragmatic effects. An experimental study then investigates these effects by artificially introducing CCs into multi-party text dialogue. Results suggest that CCs affect people’s expectations about who will speak next and whether other participants have formed a coalition or ‘party’.Together, these studies suggest that CCs require an incremental processing mechanism that can provide a resource for constructing linguistic constituents that span multiple contributions and multiple participants. They also suggest the need to model higher-level dialogue units that have consequences for the organization of turn-taking and for the development of a shared context.

Ever since dialogue modelling first developed relative to broadly Gricean assumptions about utter-ance interpretation (Clark, 1996), it has remained an open question whether the full complexity of higher-order intention computation is made use of in everyday conversation. In this paper we examine the phenomenon of split utterances, from the perspective of Dynamic Syntax, to further probe the necessity of full intention recognition/formation in communication: we do so by exploring the extent to which the interactive coordination of dialogue exchange can be seen as emergent from low-level mechanisms of language processing, without needing representation by interlocutors of each other’s mental states, or fully developed intentions as regards messages to be conveyed. We thus illustrate how many dialogue phenomena can be seen as direct consequences of the grammar architecture, as long as this is presented within an incremental, goal-directed/predictive model.