Proceedings of the IRCS Workshop on in Natural Speech, August 5-12 1992

When Given Information 'is Accented: Repetition, Paraphrase and Inference in Dialogue Marilyn A. Walker Computer and Information Science University of Pennsylvania 200 S. 33rd St. Philadelphia, Pa. 19104 ABSTRACT whereas the bitonal H+L accents mark the propositional A classic function of is to indicate the distribution content of an utterance as being inferable. The H+L* ac­ of given and new information in an utterance. This paper cent indicates that 'the desired instantiation of a salient defines given in two ways: known and salient. It then exam­ open proposition is already among the mutual beliefs' ines 63 utterances from a radio talk show corpus to determine of the conversants. The H*+L differs from H* in con­ whether either definition of given is predictive of the intona­ veying that the hearer 'should locate an inference path tional contours found in the corpus. Given as salient is found supporting the predication'([15), sect 5.4). to reliably predict one class of : the sustained tones. In order to investigate some of these claims, this work 1. Introduction develops independent logical criteria for classifying ut­ terances as consisting of given or new information, and A classic function of intonation is to indicate the distri­ then examines whether in fact the intonational real­ bution of given and new information in an utterance[5, ization of given information corresponds with the pre­ 7). The pitch accent on new information indicates the dicted intonational patterns. This paper examines ut­ information focus, the discourse entity about which a terances that consist wholly of given information, e.g. predication is being made, whereas given information repetitions of previous utterances. A definition of this typically occurs without a pitch accent. The traditional class of utterances will be provided in section 2. I will view consists of three basic claims: (1) Each phrase con­ call these INFORMATIONALLY REDUNDANT utterances, tains an item marked by the main pitch accent as the IRU's[22, 21).1 Since the classical view is that each utter­ information focus; (2) The remainder of the phrase is ance has at least one item of new information, and since given information, the ground; (3) There are a limited IRU's provide no new information, they potentially have number of special cases in which given information may an anomalous intonational realization. be accented. The data consist of 63 IRU's from a corpus of naturally Pitch accents may function to draw attention to or to in­ occurring dialogues, from a radio talk show for financial crease the amount of processing devoted to the informa­ advice.2 IRU's constitute about 12% of the utterances in tion focus[4). A complementary viewpoint is that deac­ this corpus. The instances of IRU's that have been an­ centing plays a functional role as well; it indicates to the alyzed intonationally demonstrate cases of pitch accents hearer that the deaccented item is currently salient in on given information that do not seem to fit the special the discourse[20, 17]. The combination of these two fac­ cases described in previous work. tors allows the distribution of pitch accents to guide the hearer's processing. Section 2 describes the independent criteria used to clas­ sify utterances as consisting of given information, the Other researchers have claimed that given information types of prosodic realization found in the corpus, and a may be accented in special cases such as when it is the­ number of distributional parameters used to classify the matic, contrastive, or exclamative, as well as when the speaker echoes part of a previous utterance with surprise lThese utterances are not however communicatively redun­ or incredulity or denies a presupposition in the previous dant, and yet they provide no new information. 2This corpus was in,itially tr&1111cnbed by Hirschberg and Pol­ utterance[3, 13, 18). lack from tapes of a live radio broadcast of a talk show called Speak­ ing of Yo•r Money on WCAU in Philadelphia{16]. I am grateful to A less traditional view is that given information can oc­ Julia Hirschberg for generously providing me with the tapes of the cur with a pitch accent, but the type of pitch accent is original broadcast. Digitizing, pitch tracking, and tr&1111cription qualitatively different than that on new information[l5). of the original broadcast was done with WAVES and additional programs generously supplied by Mark Liberman. There are some P&H claim that the complex bitonal accent L*+H marks problems with this corpus, mainly being that there is some over­ information that is known but not currently salient, lapping speech and the dialogues are taped in single track.

231 utterances in the corpus. The following sections exam­ inference from its antecedent(s). This defines given in­ ine particular subsets of the corpus defined by certain formation based on purely semantic properties. distributional properties, and finally section 7 proposes some issues for future research. I will also examine the interaction of salience with the se­ mantic definition of given as informationally redundant 2. Informational Redundancy that is provided above. The term given has been used to mean both semantically given as well as 'in the hearer's The term INFORMATIONALLY REDUNDANT utterances consciousness' or salient[2, 17]. In fact, Brown argues (IRU's) describes utterances that consist wholly of given that only when 'given' means 'salient' does it have rele­ information. In what follows, it will be useful to have vance for intonational realization[l]. a term to refer to the utterance(s) that originally added the propositional content of the IRU to the discourse In the remainder of this section I will first describe the situation. This the IRU's ANTECEDENT.3 way that the IRU's in the corpus can be prosodically characterized, and then define a number of distributional A definition of when an utterance counts as information­ parameters to use to determine whether it is possible to ally redundant is given below[6]:4 predict the different intonational realizations.

Definition of Informational Redundancy 2.1. Intonational Description An utterance Ui is INFORMATIONALLY REDUN­ I will use the system for intonational description pro­ DANT in a discourse situation S posed by Pierrehumbert[14], with two modifications. First, I will use the [ds] to indicate (8], 1. if Ui has already been said in S replacing the abstract L in the H*+L contour that was 2. if Ui expresses a proposition Pi, and an­ the trigger for downstep in Pierrehumbert's original sys­ other utterance u; that entails p; has al­ tem. Second, I will adopt the parameter of ':' for sus­ ready been said in S tained tones, from McLemore[l2]. This parameter indi­ 3. if Ui expresses a proposition Pi, and an­ cates that a is sustained until the next tone. 6 • other utterance u; that presupposes or implicates p; has already been said in S Most of the IRU's examined here, (48 of them), are roughly categorized into three intonational patterns, all either non-adjacent to ui or by another speaker of which end in falls; the difference between them is in the relationship between the two or more high pitch ac­ cents (H*) that each pattern contains. I will call these Condition (1) of the definition means that saying an ut­ (1) sustained tones, e.g. H*: H* LL%, (2) downstepped terance in a discourse situation adds the propositional H, e.g. H* H*[ds] LL%[8], and (3) upstepped H, e.g. H* content of that utterance to the discourse situation. H* L L%[11, 9]. Figure 1 shows a sustained tone. Fig­ Condition (2) depends on identifying what is entailed ure 2 gives an example of downstep and Figure 3 gives from what is said; it relies on concepts such as para­ an example of .7 I have limited the cases I ex­ phrase and logical inference. 5 For conditions (1) and (2), amine here to IRU's that are realized with final falls or a diagnostic of whether the propositional content of an levels. Some have a downstepped phrase accent, or final IRU is defeasible can be used to test whether the infor­ Mid[9, 10]. mation is already available in the discourse situation[19). This diagnostic cannot be used for cases defined by con­ For utterances that fit in these three main classes, there dition (3) since some of these inferences are defeasible. is often very little juncture between pitch accents in their realization. This means that the whole utterance seems Thus there are 4 logical types of IRU's defined by their to be treated as a unit since no single sub-part of the relation to their antecedent. An IRU may be a: (1) rep­ utterance is selected as focal. This is interesting due to etition, (2)° paraphrase, (3) entailment, or ( 4) non-logical the potential anomaly referred to earlier; theories that say that given information is de-accented predict that 3 Actually I use the term antecedent to refer to both the prior utterance and the proposition realized by that prior utterance, but this should not cause any confusion. 6 Neither the system presented in Pierrehumbert's dissertaticn ~ An utterance is defined as a clause, or a phrase in cases when nor the recently proposed 'standard' transcription system seems there is no finite verb in an utterance. adequate to transcribe this contour. 5 Other information is commonly included in the discourse sit­ 7The terms downstep and upstep are used to refer to precisely uation such as that which is evoked by the physical situation or defined phenomena in African tone languages; here, I am using by common-sense or plausible inference[l 7). However, I will only them simply as descriptive terms to refer to a relationship between look at a subset of the 'available' information. adjacent H• tones.

232 mary46 250 .------,,------...,...----..;;._---,,------. 240 230 220 210 200 190 180 170 160 150 140 130

40 160.25 160 .. 5 160.75 161 161.25

Figure 1: Mary 46. Salient paraphrase, Sustained Tone

the whole utterance would be de-accented, and yet this is paraphrases, 13 are entailments, and 7 are non-logical in conflict with the assumption that at least one item in inferences. 8 an utterance is always accented. Realizing the utterance with a sustained H* or with broad focus makes sense if The second main distributional parameter is salience. every item has the same information status. In this case, An IRU may have an antecedent that is currently salient the whole utterance consists of given information. in the discourse context, i.e. just said by the other speaker or within the same turn of the current speaker. There are 7 IRU 's in the corpus that are ambiguous be­ An IRU may also have an antecedent that is not cur­ tween the three patterns described above because there rently salient. Its antecedent has been DISPLACED by is only one pitch accent in the utterance. Clearly one an intervening change in topic[l]. Of the 63 tokens ex­ cannot distinguish sustaining a tone, downstepping from amined here, 42 have salient antecedents, and 21 have a tone, or stepping up to a tone when only one tone is displaced antecedents. realized. These will be called one-tone and will be dis­ cussed in more

233 ma.:r•ha47 250 240 230 220 2:1.0 200 :1.90 :1.80 :1.70 :1.60 :1.50 :1.40 :1.30 :1.20 :1.:1.0 :1.00 90 BO 70 60 50 40 1159.75 70 70.25 70.5

Figure 2: Marsha 26. Displaced paraphrase, Downstep

SustT DownS UpS One-T Other be realized with a series of downstepping tones (x2 = 9.877,p < 0.01, as compared to the other logical types Salient 8 13 4 7 10 and other contour types).

Displaced 0 12 4 0 5 Figure 5 also shows that repetitions are more likely to be sustained tones than any other logical type(p < .01). However this could be due to the fact that repetitions Figure 4: Salience as a Predictor of Contour Distribution are more likely to have a salient antecedent (p < .02). See figure 6. tokens pattern like sustained tones in other respects as well; over half of them are repetitions. If the one-tone SustT DownS UpS One-T Other contours were classified as sustained tones, the relation­ Salient 5 2 0 4 1 ship between salience and sustained tones would be even stronger (p < 0.01). Some one-tone contours will be ex­ Displaced O O 1 0 0 amined in section 4.

Both the dowm: , and upstep contours are equally likely Figure 6: Repetitions: Salient vs. Displaced An­ to have a salie, antecedent as a displaced antecedent. tecedents In section 3, I will compare examples of downstep and mstained tones that occur in similar discourse situations. Finally, a comparison of IRU's inferable from their an­ SustT DownS UpS One-T Other tecedents, ie. logical and non-logical inferences, with repetitions and paraphrases, shows that inferables are Repeat 5 2 1 4 1 less likely to be realized with one of the three main pat­ terns discussed(p < .01).9 See Figure . Paraphrase 2 18 5 0 5 Thus it seems that there is much more variability in the Entailment 0 5 1 2 5 way the inferential IRU's are realized; they are neither realized consistently with the downstepping tones pre­ Non-Logical 1 0 1 1 4 dicted by P&H nor with the stylized contours that were documented by Ladd and McLemore[15, 12, 8]. The fol­ lowing sections will dis- ,i.ss particular examples of the Figure 5: Logical Type as a Predictor of Contour contours discussed her•·

Figure 5 examines the distribution of the various logical 9 A comparison of repetitions with all the other logical types is not significant (p < .10). However a comparison of repetiticns types of IRU's with respect to the contour categories. with inferences alone is significad. (p < .05), as is a comparison of This figure shows that paraphrases are more likely to para.phrases with inferences alone (p < .05).

234 120 110 100 •• ! 80 • 10 i .,-.... so•• ; \ ; •• 121.75 122 122 .25 122 .5 122. '75 123 123. 25 123 .s

Figure 3: Joe 48. Salient paraphrase, Upstep

the just previous clause. The lexical item separate in Other I Not-Other I (56) entails a division into at least two separate parts. As shown by plot of fO in figure 1, this utterance is real­ Repetitions and Paraphrases 6 I 38 j ized with a high sustained tone, followed by a mid-level final value {cf. [9, 10]), H*: H* H[ds] L%. This is an ex­ Inferables 9 I 11 I ample of stylized intonation[8, 12]. Stylized intonation makes sense in these contexts since the information has just been said, it is certainly predictable. However the Figure 7: Inferables are more likely to be Other sense of predictability may be carried by sustained tones or a sequence of without necessarily depend­ ing on the final mid-level[15]. 3. Sustained Tones vs. Downstep When we compare 1-56 with the paraphrase of it that According to figure 4, the sustained tone contours are Mary (m) produces in 1-57, we find that this utterance, predicted by the salience of the antecedent. However in the same context is realized with a downstepping con­ why is it that there are so many downstepped contours tour rather than with the sustained tone. See figure 8. with salient antecedents? The dialogue in 1, How~ver there is a third example of an IRU in example from (56) to (58) provides three examples of IRU's. In 1-58, where Harry repeats two different ones. This is the dialogue excerpts given here, IRU's will be marked shown in figure 9. This utterance is counted as a sus­ with CAPS whereas their antecedents will be given in tained tone because of the difference between it and the italics. downstep seen in figure 8. However the fO for this ut­ terance does go down slightly as it nears the end of the (1) (52) h. and they will maintain their value ap­ phrase. It is also realized with a phrase-final level since proximately because they are variable rate funds Harry intends to continue his turn[12, 15]. (53) m. I see An almost identical context occurs in the following ex­ (54) h. Ok cerpt: (55) m. Fine (56) h. and but separate it, I DON'T WANT IT ALL IN ONE (2) (24) h. that is correct, it could be moved around (57) m. TWO DIFFERENT ONES so that each of you have 2000 (58) h. TWO DIFFERENT ONES, three would {25) m. I be even better .... (26) h. without penalty (27) m. WITHOUT PENALTY {28) h. right The IRU in (56) is shown in figure l. In 1-56, the (29) m. and the fact that I have a an account of speaker, (h), has paraphrased his own utterance from my own ...

235 200 ------,------...------...... ------.------, 1!>0 ·································· ·······················•···········1····-····························· ················•···············••4••······························ , I 180 ··························-······ ·········-························1·······•··•·····•·················· ················-···-···········-t································ 170 160 1.!50 140 = = :: _ =••·-. :=1=: # • • ..,,,. ::::::= 130 l ♦ =---=== 4=-~~:r::::: 120 110 100 :: : - =: -=: : ===== !>O ~ =::=:: \.-J- - :=: ::=::=l--~ ao 1+------+------+------+------+--~---c--'--- 7 a •-•-yO'tJ"Z."··············•-wk-re-•··········±·•···-····- rr················-·-~,n~- i ' 60 ------so ------l ... ~------...... -~-1o._.-.. 40 1.9.5 1SL75 20 20.25 20.5 20.75

Figure 12: Dave 36. Salient paraphrase, Sustained Tone

:ray1.00

150 220 .....~------,..-----~--,

210 ------200 l-+------+-- 190 ------····-··-··········· ------130 18 0 ... ·-·.,--··-··-·-·-··.-'~4&.··-··-··----· -·---· 120 ...... • ~•• ... 170 .... I ♦ • 110 ...... • 1150 6 0 ... ·-···-·-·-··-·-··-·· t1 ·-····-·-· '.. • ·-·--·-· ·········· 140 ------~--~----- ___ ._ 100 130 120 .. -·-······-··-··------+------··.--- ____ ._ __ _ 90

BO 70 :11 J __ 60 J____ ! ········-···-·---·------··~=: ·····-··· 50 50 40 .__.__ __.__ .....__.______,__;:,.., 40 44 44e2!5 44 .. S 1(5115.25 1.1156.5

Figure 13: Jane 9: Salient repetition, Downstep Figure 11: Ray 34: Salient repetition, Sustained Tone

4. One Tone Contours An example of downstep that is very similar to that given As noted in section 2.2 there are some tokens which can't in figure 8 is the repetition in example 5-9. As shown in be classified as either a sustained tone, a downstep or an figure 13, the utterance in 4-9 is realized as a series of upstep because they only have one pitch accent. For downstepped highs, with a pitch accent first on take and example 6-8 in the excerpt below, and shown in figure then money realized as an H*[ds). 14.

(5) (8) h. you can stop right there: take your money (6) ( 6) r. Uh 2 tax questions. one: since April of 81 (9) j. TAKE THE MONEY we have had an 85 year old mother living with (l0)h. absolutely..... us. Her only income has been social security plus approximately 3000 dollars from a certificate of deposit and I wonder what's the situation as as Note that while all the sustained tones have a salient far as claiming her as a dependent or does that antecedent, there are other IRU's that have a salient income from the certificate of deposit rule her antecedent and yet are not realized with sustained tones. out as a dependent? Thus I currently cannot predict when the sustained tones ( 7) h. Yes it does should occur, only when they should not. ( 8) r. IT DOES

237 ( 9) h. Yup that knocks her out.

340 i====:i===:::ma=:r:::y1=•:::i::====+=l..- j 320300 ----+------'.""•~I------+---!______,,,,. j .. These tend to be elliptical repetitions such as the one 2110 ··------: .. --.---_...---1 shown here. Figure 4 showed that these one-tone con­ 1 2 60 ----..----:·---. 1---=•----·. .. ·­ tours pattern distributionally like the sustained tones. 240 . ♦ ! .. i 220 1-----+------1------,,...... ;-- However they cannot uncontroversially be collapsed with ! I the sustained tones. 200 ----+-----1------,,...... ; 180 1------+------i---..::.•----t--l! 160 ----+------'i----"·'-----+-----!i ray1.4 140 ----,------1-----·---;i_! 1.50 I • I 120 1------+------il----:...·----t·-- I 100 1------+------.1------l---i ...... ea 1-----+------,i------,,...... ; ...... -, Y•• \are 60 tr--._-----""' 1.20 40 .____,=-::::·---+'\../:.....'..=___ _.i._- __-_.::.....___.....__. 104..25 1.10 -...... ·,...... 1. o a -····- -·······················~- -··· Figure 15: Mary 33, Salient repetition, One-Tone

70 Although this cannot be classified as a sustained tone 60 since there is only one major pitch accent, it is also an example of 'stylized' intonation[9, 12, 8].

40 5. Upstepping Contours Figure 14: Ray 8, Salient repetition, One-Tone One example of an upstepping contour was given in fig­ ure 3. Another example is given below in excerpt 9, and is shown in figure 17. A similar example is given below in 7 and shown in figure 15. (9) ( 8) j. and uh i'd like to start out an I RA for myself and my wife, she doesn't work (7) (26) h. first of all with that forty one thousand ( 9) h. well how about last year? and that's your pension alone (27) m. yes ( Intervening dialogue about eligibility for 81) (28) h. completely taxable (29) m. yes ( 17) h. ahh that then then you 're not eligible for (30) h. ok (31) m. so we're in a (32) h. you 're in a pretty healthy tax bracket bill44 300 290 (33) m. YES WE ARE 210 270 (34) h. as a result i'm not sure that I would 260 'I . 250 . -- want any of that hundred twenty thousand m 240 230 .. #'' any more treasury notes 220 - I -•.. 210 200 . uo .-,.. . 180 ... ,,, . . 170 ·~ Some of the contours classified as one-tone also share 1'0 ,. ,. .. 150 'I.I .J - the phrase-final :Mid with contours classified as sustained 140 130 tone. For example consider the excerpt below and the 120 110 corresponding fO.in figure 16. 100 ,0 10 70 ,0 50 _/ '- (8) (22) b. Are there ah .. I don't think the ah 40 ' 13 ll.25 13 • .5 13. 75 brokerage charge will be ah that excessive (23) h. No they're not excessiF but THERE ARE CHARGES Figure 16: Bill 23, Salient Non-Logical, One-Tone with Mid

238 joe23 250 .------r-----.-----"""T-----,.-----..-----....-----,-----,

::~220 1-----+-----+-----+----:----+-----+-----+-----t;======::::======:::======:======::::1:======::::======~======::::=====~ HO 200 t----+-----+-----t------:!-----+-----t---,.~-+-----t1 190 ! ! 1 ~-:-~_,.! _____, l I I • • I uo I I • ~-- i -~1-.----< 170 i------r--..---i-----:!;·;;a··.._,_,.. _ .. -"\.:.t:-.,-·-r-_,. _.,.,~ ;... _ ..L-----~·_:== 100 ----+--✓-•.J'~..·--A.;-.:.~-_. .. "'t-_._.. ___ ..., __""'.· I 7 -_.. "["..:!ii,.•- . 150 1-----•:.-:=--+_-l'----~• ..---~--+-----,1----+-----~---+-~-·--t ~:~ -----· -c·-+_.------+-----.-----+-----+----+----!

120 --.,..!'-'--...-1-----+-·----1-----+------+----+------t----l 110 __.. ----+------+------+----+-----+-----+-----! 100 1-----+-----+-----+-----ii------+-----+-----+----t ,01-----+-----1-----+-----i-+---+-----+-----+------I BO l-----+-----1-----+--~--i-+---+-----+-----+-----1

Figure 17: Joe 19: Displaced Paraphrase, Upstep

eighty one contours and shares the note of enthusiasm with those (18) j. I see, but I am for eighty two contours. (19) h. You said it. You're eligible for twenty two fifty IF YOUR WIFE IS NOT WORKING OUTSIDE OF THE HOME 7. Discussion

This paper has examined a.number of cases where given These upstepping contours sound as though the speaker information is not deaccented as in the classical view. is trying to be enthusiastic. The phrase-final tone is also I have examined the interaction of a semantic definition Mid in this particular example. Additional tokens and of given with discourse salience. Independent of whether further distributional analyses of this contour type would given information is salient or displaced, given informa­ be necessary for formulating a more precise characteri­ zation. tion is realized with a pitch accent. The work presented here should be extended to actually 6. Other Contours test whether downstep is correlated with given informa­ There are 20 IRU's whose antecedents are infer­ tion as P&H proposed[15]. The fact that 25 out of 63 able by logical inference or linguistically licensed in­ IRU's are realized with a downstepping contour could ferences such as scalar implicatures or presupposi­ be taken as weak support for their claims. However, I tions(Bridge91,Hirschberg85). As discussed in section have not compared these tokens against a sample of non­ 2.2 that these are more likely to be realized as Other redundant tokens to test whether downstep appears on type contours. An example is shown in the excerpt be­ these tokens just as frequently. Furthermore there are a low, where Harry (h) makes an entailment explicit from number of other contours that these IRU's are realized information provided in 10-7 by Jane (j). with, such as the Sustained Tone, Upstep and Other con­ tours that would not be predicted on P&H's account.

(10) ( 7) j ..... and i'm entitled to a lump sum settle­ However, this paper has argued that salience is a predic­ ment which would be between 16,800 and 17,800 tor of one class of contour, the sustained tones. Other or a lesser life annuity. and the choices of the accounts have not distinguished salient and displaced annuity um would be $125.,15 per month. that mutual beliefs in terms of intonational realization[15] or would be the maximum with no beneficiaries have suggested that salient is the only relevant notion of ( 8) h. you can stop right there: take your money given information[!]. I have shown here that, in this type ( 9) j. take the money. of dialogue, the sustained tone contour is correlated with (10) h. absolutely. YOU'RE ONLY GETTING salience. However discourse salience is not predictive of 1500 A YEAR. downstepping contours. In addition, I have shown that IRU's that are inferable from their antecedents are more Utterance 10-10 is shown in figure 18. This utterance likely to be realized with some item in narrow focus than shares the high final pitch accent with the upstepping IRU's classified as repetitions or paraphrases.

239 45.'75 46 46.25 46.5 41i.'75 41 .25

Figure 18: Jane 10: Displaced Inference, Other

I have not examined the influence of boundary tones 10. Mark Y. Liberman and Cynthia A. McLemore. The on the pragmatic use of these contours[l2]. Phrase-final structure and intonation of business telephone openings. Mid, characteristic of 'stylized' intonation[8], cuts across The Penn Review of Linguistics, 16:68-83, 1992. the contour classifications used here. IRU's frequently 11. Mark Y. Liberman and Ivan A. Sag. Prosodic form and discourse function. In CLS 10, pages 416-27, 1974. have these phrase-final Mid's, but not always. This must 12. Cynthia A. McLemore. The pragmatic Interpretation of be examined more closely in future work. Future re­ English Intonation: Sorority Speech. PhD thesis, Uni­ search should also include examination of these types of versity of Texas, Austin, 1991. utterances in other types of dialogue in order to pro­ 13. S. G. Nooteboom and J. G. Kruyt. Accents, focus distri­ vide a more general account of the use of the contours bution, and the perceived distribution of given and new described here. information: an experiment. Technical Report 538/V, IPO, Netherlands, 1987. 14. Janet Pierrehumbert. The Phonetics and of References English Intonation. PhD thesis, MIT, 1980. 1. Gillian Brown. Prosodic structure and the given/new 15. Janet Pierrehumbert and Julia Hirschberg. The mean­ distinction. In A. Cutler and D.R. Ladd, edi­ ing of intonational contours in the interpretation of dis­ tors, Prosody Models and Measurements, pa.ges 67-77. course. In Cohen, Morgan and Pollack, eds. Intentions Springer-Verlag, 1983. in Communication, MIT Press, Cambridge, MA., 1990. 2. Wallace L. Chafe. Givenness, contrastiveness, definite­ 16. Martha Pollack, Julia Hirschberg, and Bonnie Webber. ness, subjects, topics and points of view. In Charles N. User participation in the reasoning process of expert sys­ Li, editor, Subject and Topic, pages 27-55. Academic tems. In Proc. National Conference on Artificial Intel­ Press, 1976. ligence, 1982. 3. Cruttenden. Intonation. Cambridge University Press, 17. Ellen F. Prince. Toward a. taxonomy of given-new infor­ 1986. mation. In Radical Pragmatics. Academic Press, 1981. 18. Susan F. Schmerling. Aspects of English Sentence 4. Anne Cutler. Phoneme-monitoring reaction time as a function of preceding intonation contour. Perception . PhD thesis, University of Texas, 1976. Published and Psychophysics, 20:55-60, 1976. by UT Press: Austin. 19. Robert C. Stalnaker. Assertion. In Peter Cole, editor, 5. M. A. K. Halliday. Notes on contrastivity and theme ii. Synta:r and Semantics, Volume 9: Pragmatics, pa.ges Journal of Linguistics, 3:199-244, 1967. 315-332. Academic Press, 1978. 6. Julia Hirschberg. A Theory of Scalar Implicature. PhD 20. J. M. B. Terken and S. G. Nooteboom. Opposite ef­ thesis, University of Pennsylvania, Computer and Infor­ fects of accentuation and deaccentuation on verification mation Science, 1985. latencies for given and new information. Language and 7. Ray S. Jackendoff. Semantic interpretation in generative Cognitive Processe~ pa.ges 145-163, 1987. grammar. MIT Press, 1972. 21. Marilyn A. Walker. A model of redundant informa­ 8. Robert Ladd. The Structure of Intonational Meaning: tion in dialogue: the role of resource bounds. Technical Evidence from English. University of Indiana Press, Report MS-CIS-30-92, University of Pennsylvania. Com­ 1980. A Cornell University Dissertation. puter Science, 1992. Dissertation Proposal. 9. Mark Y. Liberman. The Intonational System of English. 22. Marilyn A. Walker. Redundancy in collaborative di­ PhD thesis, MIT, 1975. (published by Garland Press, alogue. In Proceedings of the fourteenth International Conference on Computational Linguistics, 1992. NY, 1979).

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