Tuning accessibility of referring expressions in situated dialogue

Accessibility theory associates more complex referring expressions with less accessible referents. Felicitous referring expressions should reflect accessibility from the addressee's perspective, which may be difficult for speakers to assess incrementally. If mechanisms shared by perception and production help interlocutors align internal representations, then dyads with different roles and different things to say should profit less from alignment. We examined introductory mentions of on-screen shapes within a joint task for effects of access to the addressee's attention, of players' actions and of speakers' roles. Only speakers' actions affected the form of referring expression and only different role dyads made egocentric use of actions hidden from listeners. Analysis of players' gaze around referring expressions confirmed this pattern; only same role dyads coordinated attention as the accessibility theory predicts. The results are discussed within a model distributing collaborative effort under the constraints of joint tasks.