Who Tunes Accessibility of Referring Expressions in Task-Related Dialogue?

Ariel (1988; 1990; 2001) has proposed that the grammatical form of an anaphor can be predicted from the ‘deemed ’ accessibility of its antecedent. The element of judgment in the term ‘deemed ’ is critical: it allows the speaker to reflect an egocentric perspective and frees choice of expression from the ac-tual contingencies of the situation in which it is uttered. Using a screen-based joint tan-gram construction task (Carletta et al., under revision), we examine the accessibility of 1775 introductory mentions for effects of situation (communication modalities and ac-tions involving the named entity) and of re-sponsibilities assigned to the participants. We find statistically significant effects of three kinds: circumstances readily available to the listener (concurrent movement of the named object); circumstances private to the speaker (hovering the mouse over the object, when the listener cannot see the mouse), and the speaker’s role in the joint task. Since ego-centrically selected forms may be under-specified, we make a preliminary attempt to discover whether referring expression usage is disabling or irrelevant.