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<Paper uid="P89-1007">
  <Title>GETTING AT DISCOURSE REFERENTS</Title>
  <Section position="4" start_page="52" end_page="52" type="metho">
    <SectionTitle>
DIFFERENT FROM THE OTHER, at least, THAT
</SectionTitle>
    <Paragraph position="0"> (/IT)'s not the way I look at it In this paper, I focus on the linguistic features of the local context, i.e., the context containing a pronoun token and its antecedent, in order to investigate the relationship between the pronominal features of demonstrativity and definiteness and the local attentional state of a discourse.</Paragraph>
  </Section>
  <Section position="5" start_page="52" end_page="52" type="metho">
    <SectionTitle>
3 Statistical Analysis of the
</SectionTitle>
    <Paragraph position="0"/>
    <Section position="1" start_page="52" end_page="52" type="sub_section">
      <SectionTitle>
Conversational Data
3.1 Method
Psychologists and sociologists studying face-to-
</SectionTitle>
      <Paragraph position="0"> face interaction have argued that the baseline of interactive behavior is dyadic rather than monadic \[4\] \[9\]; similarly, in understanding how speakers cooperatively construct a discourse, the base-line behavior must be dialogic rather than monologic. The analytic methods employed here were adapted from those used in studying social interaction among individuals. I analyzed the local context of lexical choice between it and that in four career-counseling interviews. The interviews  appear in CAPS, and the substituted pronoun appears in parentheses to the right of the original. A: and B: are used to distinguish two speakers, where relevant. Text enclosed in brackets was added by the author to clarify the context. took place in a college career-counseling office, and were not staged. The final corpus consisted of over 3 1/2 hours of videotaped conversation between counselors and students. This provided an excellent source of data, with the speakers contributing tokens of it/that at the rate of roughly 1 in every 2 sentences, or a total of 1,183 tokens in all. Nearly all of these were indexed and coded for 16 contextual variables characterizing the linguistic structure of the local context. 4 These variables fell into two classes: those pertaining to the rdN-</Paragraph>
    </Section>
  </Section>
  <Section position="6" start_page="52" end_page="416" type="metho">
    <SectionTitle>
EAR ORGANIZATION OF DISCOURSE, or to the re-
</SectionTitle>
    <Paragraph position="0"> spective locations of the antecedent and pronoun~ 5 and those pertaining to the SYNTACTIC FORM of the antecedent expression.</Paragraph>
    <Paragraph position="1"> Statistical analysis was used as a discovery procedure for finding the strongest determinants of lexical choice, rather than to test a particular hypothesis. The goal was to find the best \]it between the contextual variables and lexical choice, i.e., to include in a final statistical model only those variables which were highly predictive. I used log-linear statistical methods to construct a single best multi-dimensional model; log-linear analysis permits the use of the x-square statistic for greater than 2-dimensional tables. This is advantageous, because multi-dimensionality imposes more constraints on the statistical model, and is thus even more reliable than 2-dimensional tables in revealing non-chance correlations. In addition to multidimensionality, three other criteria guided the selection of the best \]it: a statistically significant probability for the table, meaning a probability of 5.0% or lower; statistical independence of the predictive variables from one another, i.e., that they represented truly distinct phenomena, rather than overlapping factors; and finally, that the distributional patterns were the same for each individual speaker and for each separate conversation, in order to justify pooling the data into a single set. 6 The antecedents of some of the pronouns occurred in the interlocutor's speech, but change of 4Certain repetitions, e.g., false starts, were excluded from consideration; cf. chapter 2 of 1131 SLacation was construed very abstractly, and included, e.g., measures of whether the antecedent and pronoun were in the same, adjacent, or more distant sentences; how deeply embedded syntactically the antecedent and pronoun were; how many referential expres~ons with the same or conflicting semantic features of person, number and gender intervened between the pronoun and its antecedent; and their respective grammatical roles \[131.</Paragraph>
    <Paragraph position="2"> 6The reliability of the data was tested by comparing within- and across-subjects statistical measures; i.e., I took into account the data for the conversations as a whole, each individual conversation, and each individual speaker \[13\].  speaker within the local context had no effect on lexical choice, either alone, or in concert with other factors. Before pooling the data from all conversations and all individual speakers into a single population, the variability across conversations and speakers was tested and found to be insignificant. Thus the results presented below represent a speaker behavior--lexical choice of pronoun m that is extraordinarily consistent across speakers, that is independent of whether a pronoun and its antecedent occurred in the same speaker's turn, independent of individual speaker and even of individual conversation. Consequently, it is justifiable to assume that the factors found to predict lexical choice pertain to communicatively relevant purposes. In other words, whatever these factors are, they presumably pertain not only to models of speech production, but also to models of speech comprehension.</Paragraph>
    <Section position="1" start_page="416" end_page="416" type="sub_section">
      <SectionTitle>
3.2 Results
</SectionTitle>
      <Paragraph position="0"> Table 1 gives the distribution of pronouns across the relevant contexts and gives the probabilities and x-squares for the two contextual variables and their intercept, i.e., the interaction between them/ The very low probability of 0.04% for 7Note that the 4th category of Antecedent--Other-includes a mixture of atypical arguments, primarily adverbial in nature, like the adverbial argument of go in go far.  Data, showing Absolute Frequency, Expected Frequency, and x-squares for each Cell the intercept indicates that the two variables axe clearly independent, or in other words, represent two distinct contexts. The exceedingly low probabilities of 0.01% for the contextual variables and the highly significant table x-square (i.e., close to 1) indicate that the model is extremely significant, s The correlation between the dependent dimension of lexical choice and the two independent dimensions, persistence of grnmmatical subject and persistence of grammatical form, presents an intuitively very satisfying view--yet not an obvious one a priori---of how all three variables conspire together to convey the current attentional status of a discourse referent* First I will summarize the effects of the two contextual variables one at a time. Then I will review the distributionally significant facts as a whole.</Paragraph>
      <Paragraph position="1">  to occur in exactly one of the two contexts, and that was likely to occur in the opposing context. If both referring expressions were subjects, then the lexical choice was far more likely to be it than that. All it took for the balance to swing in favor of the demonstrative was for either the pronoun itself or for its antecedent to be a non-subject. The two relevant contexts, then are: * those in which both the antecedent and the target pronoun are syntactic subjects; =~ IT * all other contexts. =~ THAT Parallelism has sometimes been suggested as an organizing factor across clauses. It is certainly a strong stylistic device, but did not make a strong enough independent contribution to the statistical model to be included as a distinct variable. To repeat, the crucial factor was found to be that both expressions were subjects, not that both had the same grammatical function in their respective clauses. In SS4.1 I will review the relationship of these results to the centering literature \[I\] \[5\] \[6\]. Second Dimension: Persistence of Grammatical Form. While many grammatical distinctions among sentence constituents are possible, the syntactic form of a pronoun's antecedent correlated with the choice between it and that in the following very specific way. The 3 discriminating contexts were where the antecedent was: * any pronoun--the lexical choice for an antecedent pronoun had no effect on the lexical choice of the subsequent pronoun; =~ IT * a canonical ~P headed by a noun (including nominalizations); =~ IT or THAT * and all other types of constituents. =~ THAT The latter category included gerundives, infinitival expressions, and embedded finite clauses. 9 For contexts with a pronominal antecedent, the lexical choice was far more likely to be it. For canonical NP antecedents, it and that were equally likely, regardless of the type of head. For other types of constituents, that was far more likely. Thus there are two opposing contexts and one which doesn't discriminate between the two pronouns, i.e., a context in which the opposition is neutralized.</Paragraph>
      <Paragraph position="2"> degCf. \[14\] for &amp; detailed discussion of how the precise dividing llne between types of antecedents was determined. The dynamic component of this dimension is that it indicates, for a consecutive pair of co-specifying expressions, whether there has been a shift towards a surface form that is syntactically more compact and semantically less explicit, and if so, how great a shift. In the first context, where the antecedent is already pronominal, there is no shift, and it has a much higher probability of occurrence than that. The context in which there is a shift from a lexical NP to a phrasal NP, i.e., a shift from a reduced form to an unreduced one, but no categorial shift, doesn't discriminate between the two pronouns. The context favoring that is the one in which there is not only a shift from a single word to a multi-word phrase, but also a change in the categorial status of the phrase from a non-NP constituent to a lexical NP.</Paragraph>
      <Paragraph position="3"> Full 3-way model. Table 2 displays the data in a finer-grained two-dimensionai x-square table in order to show separately all 4 of the possible outcomes, i.e., it or that as a subject or non-subject. In this table, the row headings represent the antecedent's form and grammatical role; the column headings represent the lexical choice and grammatical role of the subsequent pronominal expression. Each cell of the table indicates the absolute frequency, the expected frequency given a non-chance distribution, and the cell x-square, with the latter in boldface type to indicate the significant cells. This is a somewhat more perspicuous view of the data because it can be displayed schematically in terms of initial states, final states, and enhanced, suppressed or neutral transitions, as in Fig. 1. However, it is also a somewhat misleading transformation of the 3-dimensional view given in table 1, because it suggests that the grammatical role of a pronoun and that of its antecedent are independent factors. Since the statistical model shown in table I is actually the best fit of the data, better than other models that were tested in which the grammatical role of each expression was treated separately \[13\], it is crucial to recognize that the statistically significant factor is the pair-wise comparison of subject status.</Paragraph>
      <Paragraph position="4"> Large cell x-squares in Table 2 indicate the significant contexts, and a comparison of the absolute and expected frequencies in these cells indicate whether the context is significantly frequent or significantly infrequent. Thus there ar~ 3 types of cells in the table representing the contexts of lexica\] choice as chance events, as enhanced events, or as suppressed events. In Fig. 1, I have translated  1. Pro-Subj ~&amp;quot; IT-Subj 2. -I THAT-Subj 3. IT-NonSubj 4. -I THAT-NonSubj 5. Pro-NonSubj IT-Subj 6. THAT-Subj 7. I- IT-NonSubj  a set of State Transitions the table into a set of 3 types of state transitions. Initial states are in the left column and final states in the right one. The 3 types of transition are one which is unaffected by the contrast between it and that (no symbol), one which is enhanced (~-), and one which is suppressed (-t). The initial states in boldface indicate for each antecedent type which of the two grammatical role states was more likely, subject or non-subject. Absence of final states for the nonNP-Subj initial state indicates that this set of contexts is extremely rare. In the following section, I discuss the relation of these events to an abstract model of attentional state.</Paragraph>
    </Section>
  </Section>
  <Section position="7" start_page="416" end_page="416" type="metho">
    <SectionTitle>
4 Discussion
</SectionTitle>
    <Paragraph position="0"> The outcome of this study is not a model of attentionai processes per #e, but rather, a set of factors pertaining to attentional structure that elucidates the shifting functions of the demonstrative pronoun in English discourse. The particular function served by that seems to depend on what functional contrasts are available given the current attentionai state.</Paragraph>
    <Paragraph position="1"> It is most useful to think of the data in terms of two major categories of phenomena. The first category is where a discourse entity has already been mentioned pronominally. In this case, maintenance of reference in subject grammatical role is a particularly signficant determinant of the choice between it and that. This effect is discussed in SS4.1 in relation to the notion of centering. The second category is where a discourse entity most recently evoked by a multi-word phrase is subsequently referenced by a pronoun. While grammatical role is relevant here, its relevance seems to depend on a more salient distinction pertaining to the syntactico-semantic type of the discourse entity, as discussed in SS4.2.</Paragraph>
    <Section position="1" start_page="416" end_page="416" type="sub_section">
      <SectionTitle>
4.1 Definite/Demonstrative
Pronouns and Centering
</SectionTitle>
      <Paragraph position="0"> The literature on attentionai state has shown that both pronominalization and grammatical role affect the attentionai status of a discourse entity. In this section I will show how the use of the definite pronoun it conforms in particular to the predictions made by Kameyaxna \[6\] \[5\] regarding canonicai and non-canonical center-retention, and that the demonstrative pronoun is incompatible with center-retention.</Paragraph>
      <Paragraph position="1"> The centering model predicts that an utterance will contain a referent that is distinguished as the backward looking center (Cb) \[1\], and that if the Cb of an utterance is coreferentlai with the Cb of the prior utterance, it will be pronominallzed \[1\].</Paragraph>
      <Paragraph position="2"> Kameyama \[6\] proposes that there are two means for retaining a discourse entity as the Cb, canonical center-retention--both references in subject role--and non-canonical center retention--neither reference in subject role. As shown in Fig. 1, the most enhanced context for lexical choice of it (context 1) was where both the pronoun and its pronominal antecedent were subjects, i.e., canonical center-retention. The next most enhanced context for it (context 7) was where neither the pronoun nor its pronominal antecedent were subjects, i.e., non-canonical center-retention. Thus, the definite pronoun correlates with both canonical and non-canonical center retention.</Paragraph>
      <Paragraph position="3"> Lexical choice of it is actively suppressed in contexts which are incompatible with centerretention. Note in Fig. 1 that if the antecedent is neither a pronoun nor a subject, a subsequent reference via it in subject role is suppressed (contexts 13 and 21). The only (non-rare) context where an it subject is neither enhanced nor suppressed is  where the antecedent is a canonical NP in subject role (context 9) (cf. SS4.2).</Paragraph>
      <Paragraph position="4"> The demonstrative pronoun is actively suppressed in the case of canonical center-retention (context 2); i.e, given two successive pronominal references to the same entity where reference is maintained in subject role, the referent's attentional state is such that it precludes demonstrative reference. Use of that is also suppressed if the antecedent is a potential candidate for canonical center retention, even if reference is not maintained in subject role (context 4).</Paragraph>
      <Paragraph position="5"> Attentional state is only one component of a discourse structure. The discourse model as a whole will contain representations of many of the things to whcih the discourse participants can subsequently refer, including discourse entities evoked by NPs, and additionally, as argued by Webber \[18\], discourse segments. Webber notes that discourse segment referents may have a different star tus from the discourse entities evoked by NPs, at least until they have been pronominally referenced. However, she suggests that when a demonstrative pronoun refers to a discourse entity, it accesses that entity by a process which first involves accessing the discourse segment in which the discourse entity is introduced. In other words, she posits two distinct referential processes, deictic and anaphoric reference, and suggests that even when a demonstrative pronoun refers to a discourse entity, the process of finding the referent is distinct in kind from anaphoric reference to the same entity. While I have no evidence that bears directly on such a claim, my data do indicate that some entities in a discourse segment are ordinarily unavailable via the demonstrative pronoun, namely entities that would be expected canonical centers, as described in the preceding paragraph.</Paragraph>
      <Paragraph position="6"> Thus my data support the view that there are distinct processes for accessing entities in the model. It is relevant to note here that the notion of eb is generally discussed in terms of links between successive utterances. Since there is an extraordinary frequency of conjoined sentences in conversational language, I distinguished between utterances and independent clauses within an utterance. The successive references in my data were in successive sentences a majority of the time (roughly 2/3; cf. \[13\]), but were sometimes separated by one or more sentences (roughly 1/6) and sometimes occurred in the same sentence (roughly 1/6). This distance factor had no correlation with lexical choice of pronoun, which suggests that discourse segment structure interacts with centering.</Paragraph>
      <Paragraph position="7"> The relevant local context for center-retention may not be successive sentences/utterances, but rather, successive sentences/utterances within the same discourse segment. In any case, for the data presented here, the relevant local context consisted of two successive co-specifying phrases, not two successive utterances.</Paragraph>
      <Paragraph position="8"> Since the primary objective of this study was to examine various features of the context immediately preceding a given type of pronoun, rather than to track the discourse history of particular entities, little can be said here about the general case of multiple successive references to the same entity. However, I did investigate a subset of this general case, namely, successive pronominal references to the same entity where the initial mention was a canonical NP, and where each next co-specifying pronoun served as the antecedent for a subsequent pronoun. I refer to these as pronoun chains. 1deg The relative likelihood of it and that was the same for the first slot in the chain, which conforms to the general distribution for pronouns with NP antecedents. The ratio of it to that in the last position of a chain conforms to chance, i.e., it equals the ratio of it to that in the pronoun chain sample. But within a chain, that is strongly predicted by persistence of grammatical form.</Paragraph>
      <Paragraph position="9"> The demonstrative occured rarely within chains, but where it did occur, either the demonstrative token or its antecedent was a non-subject. This was found to he the only factor pertaining to linguistic structure that affected the occurrence of that within a pronoun chain.</Paragraph>
      <Paragraph position="10"> A final set of conclusions derived from the pronominal initial states in Fig. 1 pertains to the non-predictive contexts, i.e., those which neither enhance nor suppress center-retention, and those which neither enhance nor suppress demonstrative reference. These are cases where there is either a shift in grammatical role, or where the lexical choice is that (contexts 3, 5, 6 and 8). When a center is not retained across two successive utterances (in the same discourse segement), then it is likely that the global context is affected \[1\], perhaps by a center-shift (cf. \[5\]), or by a segment boundary (cf. \[7\], \[11\]). Centers seem generally to be unavailable for demonstrative reference, but contexts 6 and 8 ldegThe term ~nm to have appeared in the philosophical and llngu~tic literature at about the same time, e.g., in worlm by K. Donnellan, C. Chastain, M. Halliday and D. Zubin. There were a total of 101 such chains comprising 305 total pronoun toker~; they ranged in length from 2 to 13 pronomm.</Paragraph>
      <Paragraph position="11">  in Fig. 1 perhaps represent a mechanism whereby an entity maintained as center can become available for demonstrative reference; e.g., context 6 may coincide with the chaining context discussed in the preceding paragraph, whereby a locally focussed entity can be accessed by that just in case the prior reference was a non-subject. Context 8 suggests that demonstrative reference is more available in contexts of non-canonical center retention than canonical center retention.</Paragraph>
    </Section>
    <Section position="2" start_page="416" end_page="416" type="sub_section">
      <SectionTitle>
4.2 Non-Centered Discourse Enti-
</SectionTitle>
      <Paragraph position="0"> ties I have argued elsewhere that the crucial distinction for the category of non-pronominal antecedents is the contrast between true NPS with NP syntax, versus all other types of syntactic arguments (\[12\] \[14\]). This raises two important issues pertaining to the status of the discourse entities evoked by Nl's versus other kinds of arguments.</Paragraph>
      <Paragraph position="1"> The first is that if non-NP arguments evoke discourse entities, which they certainly must, such entities apparently have a different status in the model than discourse entities evoked by NPs, given that the combination of lexical choice between it and that and grammatical function so clearly distinguish them. The second issue is that although the difference in status seems--at first blush--to correlate with a syntactic property, the distinction may ultimately be semantic in nature. I will discuss each issue in turn.</Paragraph>
      <Paragraph position="2"> Two of the non-pronominal initial states in Fig.</Paragraph>
      <Paragraph position="3"> 1 are distinguished by neither enhancing nor suppressing any of the possible transitions to it or that: NP subjects (9-12), and non-NV non-subjects (17-20). The extreme rarity of the latter suggests that non-NPs don't occur as grammatical subjects, or that when they do, they are not likely to be reevoked by a pronoun. On the other hand, NP subjects are fairly frequent in the contexts where it or that occurs with a non-pronominal antecedent, thus the absence here of enhanced or suppressed transitions suggests that an entity mentioned as an NP subject is free to be accessed in a variety of ways, or more precisely, that it has a relatively unspecified attentional state. It is neither a particularly likely Cb nor is it particularly available or unavailable for demonstrative reference.</Paragraph>
      <Paragraph position="4"> The two remaining non-subject initial states, i.e., NP non-subjects and non-NP non-subjects, both suppress subsequent reference via it subjects, as mentioned in the previous section. While NP subjects apparently have a somewhat unspecified attentional status, NP non-subjects enhance the lexical choice of non-subject that. It appears that discourse entities evoked by NPs which are not subjects are in an attentional state that is quite different from that of canonical center retention.</Paragraph>
      <Paragraph position="5"> It is especially interesting that when the antecedent is a non-NP non-subject, a subsequent pronominal reference is most likely to be demonstrative, and most likely to be a subjectJ 1 The enhancement of a that-subject context is completely contrary to the pattern established for subjects and for the demonstrative pronoun. These facts contribute to the view that entities evoked by non-NP constituents have'a special status, but what this status is remains to be determined. In previous work, I emphasized the syntactic distinction with respect to lexical choice between it and that \[14\]. Although the most obvious difference is the purely syntactic one, the syntactic distinction between NP and non-NP constituents has a number of semantico-pragmatic consequences. In discussing the nominal and temporal anaphora within Kamp's framework of discourse representation structures (DRS), Partee raised the question of the difference in status between eventdescribing clauses and nominalizations \[10\]. Independent clauses differ from the class of non-NP constituents under consideration here in that the latter occur as arguments of superordinate verbs, and are thus entities participating in a described situation, as well as descriptions of situations. However, true noun phrases--whether they describe events or not--can have definite or indefinite determiners, and cannot have tense or any aspectual categories associated with the verb. The study presented here brings us no closer to a solution to the questions posed by Partee regarding the ontology and representation of different kinds of event descriptions, but it does offer further confirmation that entities evoked by NP and non-sP constituents have a different conceptual status, given the different possibilities for lexical choice and grammatical role of a subsequent pronominal mention.</Paragraph>
    </Section>
  </Section>
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