Topic Persistence 48757 Stanley ref Manage in Olo

Table 5.6. Probability of error values for referential distance distinctions forms zero Vaff pro pro Vaff noun noun Vaff NP NP Vaff name name Vaff zero .0415 .0000 .0000 .0000 .0000 .0000 .0000 .0000 .0000 Vaff .0415 .0000 .0001 .0000 .0000 .0000 .0000 .0000 .0000 pro .0000 .0000 .1577 .0000 .0058 .0001 .0011 .0061 .0226 pro Vaff .0000 .0001 .1577 .0000 .0000 .0000 .0000 .0002 .0006 noun .0000 .0000 .0000 .0000 .0469 .3026 .0704 .3628 .1610 noun Vaff .0000 .0000 .0058 .0000 .0469 .3136 .7972 .4896 .8022 NP .0000 .0000 .0001 .0000 .3026 .3136 .3889 .9297 .5858 NP Vaff .0000 .0000 .0011 .0000 .0704 .7972 .3889 .6051 .9354 name .0000 .0000 .0061 .0002 .3628 .4896 .9297 .6051 .6746 name Vaff .0000 .0000 .0226 .0006 .1610 .8022 .5858 .9354 .6746 From table 5.6 we can conclude that the activation as measured by referential distance shows no sig- nificant difference between zero and verbal affixes, but does show a significant difference between them and all other categories of referential form. In the same way pronouns and pronouns with verb affixes are not significantly different from each other, but both are distinct from all other categories. The nominals: nouns, noun phrases, and names, whether with verb affixes or without, are not signifi- cantly different from each other, but are significantly different from the set of pronouns and the com- bined set of verbal affixes and zeros. The parameter of referential distance allows a three way distinction between zeroaffixes, pronouns, and nominals. From this information we can see that the activation level of the different classes as measured by the central tendency of referential distance for each class is distinct. The results of the Mann Whitney U test allow us to claim that referential distance does impact activation, even though it is not the only thing that does. The results support the two acti- vation models since they both predict that activation is affected by distance. Finding a correlation be- tween referential distance and referential form means that a strict prominence account is ruled out, since it predicts no correlation. The episode model is considered unlikely since a highly significant cor- relation was found and that the patterning of correlation is congruent with an activation account. That is, the significance is not randomly distributed among the different forms, but rather falls into three distinct classes, zeroverbal affixes, pronouns, and nominals.

5.4 Topic Persistence

Topic persistence is a measure of how many times in the next ten clauses a given participant will be referred to. Distinctions in topic persistence counts must be forward looking; they cannot rely on cur- rent memorial activation. Any correlations between topic persistence counts and referential form are inconsistent with the models of recency, episodes, and memorial activation. All three of these models are current state models. They depend on what has happened up to this point in the discourse. Topic persistence does not depend on the current state but is a measure of future occurrences. Each of the three models, recency, episodes, and memorial activation, make identical predictions of no correlation between topic persistence and referential form. They make the prediction for different reasons. The recency model claims that only the distance since last mention can matter in determining 80 Results and Analysis referential form, so future mentions cannot be taken into account. Episode models claim that crossing an episode boundary causes a change in referential form. Since the effect occurs only on the crossing of a boundary, it must be unaffected by persistence of a referent in the discourse. Memorial activation claims that a nominal is used only for referents which have low activation and pronominals are used for referents with high activation. 3 Current activation is not affected by how long a referent is going to stay in the register, so memorial activation must predict no correlation between topic persistence and referential form. While three of the competing models predict no correlation between topic persistence and referential form, two models, Goal Oriented Activation and prominence, do predict a correlation. Prominence pre- dicts a correlation on the assumption that referents with different levels of importance are referred to by different forms. A referent that is going to appear in the discourse for a large number of clauses is likely to be an important referent, and so a correlation between persistence and prominence is expected. Goal Oriented Activation is a model that looks not only at the current state of activation, but also at the goals the speaker has for a given participant. The topic persistence measurement is a good indica- tion of this future planning, and so Goal Oriented Activation predicts a correlation between topic per- sistence and referential form. To look at topic persistence we again deal with the central tendencies for each form. This time, in- stead of dealing with referential distance, we look at the parameter of topic persistence. What we are concerned to find out is whether there is any correlation between topic persistence and individual ref- erential forms or form classes. This is done by comparing the central tendency of each form class with the central tendencies of all the other form classes. The first step is a comparison of the central tenden- cies for topic persistence. Table 5.7 gives the mean topic persistence figures for the different referential forms of third-person referents. Of particular note are the distinctions of pronoun, noun, noun phrase, and name from their respective forms with coreferential verb affixes. In each case the topic persistence level is almost twice as high for forms with coreferential verb affixes. On the whole, this reflects a dis- tinction between forms that are not grammatical arguments of the verb forms with no correferential affix and forms which are grammatical arguments. Besides the topic persistence for the next ten clauses, the mean uninterrupted topic persistence value is given in table 5.7. This value is the number of continuous clauses a referent occurs in. Table 5.7. Mean values of topic persistence for each referential form Form Mean number of occurrences in the next 10 clauses topic persistence Mean uninterrupted topic persistence zero 3.299 1.897 verb affix 3.181 1.911 pronoun 2.73 1.73 pronoun and verb affix 3.622 2.353 noun .806 .139 noun and verb affix 1.94 1.182 noun phrase 1 .552 noun phrase and verb affix 1.917 1.208 name 1.923 1.615 name and verb affix 5.182 3.955 The mean topic persistence figures give us a picture of the central tendencies for each referential form. They do not tell us whether any one value is significantly different from any other value. We 5.4 Topic Persistence 81 3 It is a little more complicated in that it is a speaker’s estimate of the listener’s activation and the speaker would opt for a nominal if he wasn’t sure if the activation level was sufficiently high. can not argue a correlation between topic persistence and referential form without performing a statistical analysis. The test for significance is the same Mann Whitney U test that was used to de- termine the significance of referential distance. Table 5.8 shows the probability of error p value in saying that two referential categories have a significantly different level of topic persistence. Those values that are boxed show greater than a .01 level for p. 4 That is, we can conclude with at least a 99 percent assurance that these referential forms are really distinguishable by topic persis- tence. The table can be read either horizontally or vertically. As expected from table 5.7, pronoun, noun, and noun phrase are shown to be significantly different from those same forms with coreferential affixes. This indicates that referents that have a grammatical role, that is, they are coreferential with a verb affix, are more persistent and therefore more important than referents which do not have the status of a grammatical argument. Table 5.8. Probability of error values for topic persistence distinctions forms zero Vaff pro pro Vaff noun noun Vaff NP NP Vaff name name Vaff zero .83 .0408 .0168 .0000 .0008 .0000 .0108 .0146 .0727 Vaff .83 .021 .0017 .0000 .0004 .0000 .0076 .0138 .0551 pro .0408 .021 .0001 .0001 .1109 .0003 .4193 .1027 .0013 pro Vaff .0168 .0017 .0001 .0000 .0000 .0000 .0001 .0020 .6819 noun .0000 .0000 .0001 .0000 .0049 .8063 .0003 .2725 .0000 noun Vaff .0008 .0004 .1109 .0000 .0049 .0153 .3820 .5315 .0003 NP .0000 .0000 .0003 .0000 .8063 .0153 .0012 .3940 .0000 NP Vaff .0108 .0076 .4193 .0001 .0003 .3820 .0012 .2174 .0011 name .0146 .0138 .1027 .0020 .2725 .5315 .3940 .2174 .0044 name Vaff .0727 .0551 .0013 .6819 .0000 .0003 .0000 .0011 .0044 Since it is difficult to spot groupings of significant values in table 5.8, the actual values have been changed to a shading scheme in figure 5.1. The light gray shade represents a significant distinction be- tween topic persistence values p£.01. Dark gray reflects that the topic persistence of two forms can- not be claimed to be significantly different. 82 Results and Analysis 4 Editor’s note: The meaning of this sentence is unclear since no values are boxed by a heavy line such as those in table 5.6. forms zero Vaff pro pro Vaff noun noun Vaff NP NP Vaff name name Vaff zero Vaff pro pro Vaff noun noun Vaff NP NP Vaff name name Vaff Figure 5.1. Significant differences for topic persistence distinctions. Three models, recency, episodes, and memorial activation, predict that no correlation should be found between topic persistence and referential form. The other two models, Goal Oriented Activation and prominence, predict that such a correlation is expected. The topic persistence data supports Goal Oriented Activation and prominence because such a correlation does occur. This is illustrated in figure 5.1: the number of light gray cells shows that there clearly is a correlation between topic persistence and referential forms across a broad number of forms. The Goal Oriented Activation model and a prominence account are supported by the topic persistence data. This data supports the claim that an adequate theory of reference must include a component which looks forward in the text. After examin- ing referential distance and topic persistence, we have found that only Goal Oriented Activation can handle the data produced by each measurement. Character importance Two of the models, Goal Oriented Activation and prominence, predict that the importance level of individual characters make a difference in the choice of referential forms. The other three models, re- cency, episodes, and memorial activation, predict that no correlation should be found between the im- portance level of a character and the referential form. It is always difficult to determine the importance of a character in a story in a noncircular way, and still be fairly certain that only important characters are found in their set and only unimportant char- acters are found in their set. The way I chose to do this is by absolute frequency. I assume that impor- tant characters are on average mentioned more over the course of the whole story than unimportant characters. By checking the two ends of the scale it should be possible to form two exclusive sets of im- portant characters and unimportant characters. The values chosen should be extreme enough to do this and still allow a fairly large sample. The values chosen in this study are referents which occur three or fewer times and more than twenty times. There are 128 occurrences of third-person referents that occur three or fewer times. There are 243 occurrences of referents that occur more than twenty times. The occurrence figures are given in table 5.9, where the numbers in parentheses are the num- bers originally generated. On closer examination, all six occurrences of pronouns, which referenced participants that occur more than twenty times in the text, involved verbs which could not take an af- fix for purely phonological reasons. The table has been adjusted to reflect this by moving the six occurrences from the pronoun row to the pronoun with verb affix row. 5.4 Topic Persistence 83 Table 5.9. Comparison of very infrequent and very frequent referents Form £3 20 Both zero 17 13.3 41 16.9 58 15.6 verb affix 48 37.5 154 63.4 202 54.4 pronoun 5 3.9 0 6 0.0 2.5 5 11 1.3 3.0 pronoun and verb affix 4 3.1 25 19 10.3 7.8 29 23 7.8 6.2 noun 15 11.7 0.0 15 4 noun and verb affix 7 5.5 1 .4 8 2.2 noun phrase 20 15.6 0.0 20 5.4 noun phrase and verb affix 6 4.7 4 1.6 10 2.7 name 2 2.16 6 2.5 8 2.2 name and verb affix 4 3.1 12 4.9 16 4.3 Totals 128 100 243 100 371 100 There are three very large holes in the data. No referent that occurs more than twenty times in a text is ever referenced by just a pronoun, noun, or noun phrase. If referential forms were randomly associ- ated with referents that occurred more than twenty times, then the occurrences in each row should be roughly proportional to the total number of references to referents that occur more than twenty times divided by the total number of references in this sample. That ratio is 243371 or .65. For the referen- tial forms of pronoun, noun, and noun phrase to approach this random level they would need to have 65 percent of their total occurrences to show up in the greater than twenty column. These figures would be roughly 3, 9 and 13, respectively. That these are all zero shows that this is not a random oc- currence. Also, this is consistent with what was found in the previous section on topic persistence in re- gards to these referential forms. These forms have a low level of topic persistence, which is characteristic of unimportant referents. Here we find that they are not associated with important refer- ents using an independent measure. The two independent measures reinforce each other. This enables us to conclude that the level of importance of a referent in a discourse is reflected by the choice of ref- erential form. This is consistent with the Goal Oriented Activation model and a prominence account, which predict that character importance influences selection of referential form. It is entirely inconsis- tent with recency, episodes, and memorial activation accounts because they predict that the importance of a character is immaterial to the choice of referential form.

5.5 Boundaries