PRONOUNS, NAMES, AND THE CENTERING OF ATTENTION IN DISCOURSE

Centering theory, developed within computational linguistics, provides an account of ways in which patterns of interutterance reference can promote the local coherence of discourse. It states that each utteranc e in a coherent discourse segment contains a single semantic entity-th e backward-looking center-that provides a link to the previous utteran ce, and an ordered set of entities-the forward-looking centers-that of fer potential links to the next utterance. We report five reading-time experiments that test predictions of this theory with respect to the conditions under which it is preferable to realize (refer to) an entit y using a pronoun rather than a repeated definite description or name. The experiments show that there is a single backward-looking center t hat is preferentially realized as a pronoun, and that the backward-loo king center is typically realized as the grammatical subject of the ut terance. They also provide evidence that there is a set of forward-loo king centers that is ranked in terms of prominence, and that a key fac tor in determining prominence-surface-initial position-does not affect determination of the backward-looking center. This provides evidence for the dissociation of the coherence processes of looking backward an d looking forward.