The Effect of Pitch Accenting on Pronoun Referent Resolution

The Effect of Pitch Accenting on Pronoun Referent Resolution Janet Cahn Massachusetts Institute of Technology Cambridge, MA 02139 USA cahn~media.mit.edu Abstract By strictest interpretation, theories of both centering and intonational meaning fail to predict the existence of pitch accented pronominals. Yet they occur felicitously in spoken discourse. To explain this, I emphasize the dual functions served by pitch accents, as markers of both propo- sitional (semantic/pragmatic) and atten- tional salience. This distinction underlies my proposals about the attentional conse- quences of pitch accents when applied to pronominals, in particular, that while most pitch accents may weaken or reinforce a cospecifier's status as the center of atten- tion, a contrastively stressed pronominal may force a shift, even when contraindi- cated by textual features. Introduction To predict and track the center of attention in dis- course, theories of centering (Grosz et al., 1983; Brennan et al., 1987; Grosz et al., 1989) and im- mediate focus (Sidner, 1986) rely on syntactic and grammatical features of the text such as pronominal- ization and surface sentence position. This may be sufficient for written discourse. For oral discourse, however, we must also consider the way intonation affects the interpretation of a sentence, especially the cases in which it alters the predictions of centering theories. I investigate this via a phenomenon that, by the strictest interpretation of either centering or intonation theories, should not occur -- the case of pitch accented pronominals. Centering theories would be hard pressed to pre- dict pitch accents on pronominals, on grounds of redundancy. To bestow an intonational marker of salience (the pitch accent) on a textual marker of salience (the pronominal) is unnecessarily redundant and especially when textual features correctly pre- dict the focus of attention. Intonational theories would be similarly hard pressed, but on grounds of information quality and efficient use of limited resources. Given the serial and ephemeral nature of speech and the limits of working memory, it is most expedient to mark as salient the information-rich nonpronominals, rather than their semantically impoverished pronominal stand-ins. To do otherwise is an injudicious use of an attentional cue. However, when uttered with contrastive stress on the pronouns, (I) John introduced Bill as a psycholinguist and then HE insulted HIM. (after Lakoff, 1971) is felicitously understood to mean that after a slanderous introduction, Bill re- taliated in kind against John. What makes (1) felicitous is that the pitch ac- cents on the pronominals contribute attentional in- formation that cannot be gleaned from text alone. This suggests an attentional component to pitch ac- cents, in addition to the propositional component explicated in Pierrehumbert and Hirschberg (1990). In this paper, I combine their account of pitch ac- cent semantics with Grosz, Joshi and Weinstein's (1989) account of centering to yield insights into the phenomenon of pitch accented pronominals, and the attentional consequences of pitch accents in general. The relevant claims in PH90 and GJW89 are re- viewed in the next two sections. Pitch accent semantics A pitch accent is a distinctive intonational con- tour …

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