1. The Effect of Contour Type and Epistemic Modality on the Assessment of Speaker Certainty
Agustín Gravano1 · Stefan Benus2 · Julia Hirschberg1
Elisa Sneed German3 · Gregory Ward3
1 Columbia University
2 Univerzity Konštantína Filozofa
3 Northwestern University

2. Agustín Gravano Speech Prosody 2008
Overview
Previous researchers disagree about the role of epistemic would in utterance interpretation.
A: Who’s the British woman over there?
B: That would be J. K. Rowling.
Epistemic would conveys...
Tentativeness (Palmer 1990, Perkins 1983)
A high degree of speaker certainty (Ward et al. 2003)
Agustín Gravano Speech Prosody 2008

3. Agustín Gravano Speech Prosody 2008
Overview
What is the relation between epistemic would and perceived speaker certainty?
What role does the intonational contour play?
Two perception experiments
Textual condition
Spoken condition
Agustín Gravano Speech Prosody 2008

4. Agustín Gravano Speech Prosody 2008
Epistemic modality
Marks the speaker’s estimation of the likelihood that a certain proposition is true in context.
A: Who’s the British woman over there?
B: That must be J. K. Rowling.
That could be J. K. Rowling.
That might be J. K. Rowling.
How is the perception of speaker certainty affected by the use of epistemic would?
That would be J. K. Rowling.
Agustín Gravano Speech Prosody 2008

5. Perception Study 1: Textual Condition Task Overview
Participants were:
1) Presented with written dialogues.
2) Asked to assess the speaker certainty of a target utterance.
Agustín Gravano Speech Prosody 2008

6. Perception Study 1: Textual Condition Materials
[Context: David is at his desk when a co-worker knocks on the door.]
Co-worker: David, I'm looking for this guy named Frank Jackson.
David: That’s the new guy. or
That would be the new guy.
Agustín Gravano Speech Prosody 2008

7. Perception Study 1: Textual Condition Experiment Design
Each session contained 60 tokens:
20 stimuli (only one stimulus from each set)
40 fillers without any of the target constructions
Presented in a random order.
Participants rated the perceived certainty of each token on a 5-degree Likert scale:
Very uncertain, Somewhat uncertain, Neither certain nor uncertain, Somewhat certain, Very certain.
Agustín Gravano Speech Prosody 2008

8. Perception Study 1: Textual Condition Computer Interface
Agustín Gravano Speech Prosody 2008

9. Perception Study 1: Textual Condition Collected Data
12 participants (8 female, 4 male, mean age: 20.3)
240 data points (120 would be, 120 is)
Participants’ responses were:
1) Converted into numeric values:
Very uncertain  2
Somewhat uncertain  1
Neither certain nor uncertain  0
Somewhat certain  1
Very certain  2
2) Normalized using z-scores.
Agustín Gravano Speech Prosody 2008

10. Perception Study 1: Textual Condition Results
Mean certainty of
would be tokens: 0.13 ± 1.11
is tokens: 0.03 ± 1.04
One-way ANOVA: No significant difference.
No evidence of a difference in perceived certainty between modal would and indicative be, in a textual condition.
Agustín Gravano Speech Prosody 2008

11. Agustín Gravano Speech Prosody 2008
What is the case in a spoken condition?
How is the perception of speaker certainty affected by:
the use of epistemic would?
the use of a particular intonational contour?
Agustín Gravano Speech Prosody 2008

12. Perception Study 2: Spoken Condition Task Overview
Participants were:
1) Presented with written dialogues and a recorded target utterance.
2) Asked to assess the speaker certainty of each target utterance.
Agustín Gravano Speech Prosody 2008

13. Perception Study 2: Spoken Condition Computer Interface
Agustín Gravano Speech Prosody 2008

14. Perception Study 2: Spoken Condition Intonational Contours
Simple declarative contour (H*) H* L- L%
Downstepped contour H* !H* (!H*) L- L%
Yes-no-question contour (L*) L* H- H%
Agustín Gravano Speech Prosody 2008

15. Perception Study 2: Spoken Condition Materials
20 stimulus sets, each with six variations of the same utterance (= 120 files):
Recorded by a non-professional male speaker of American English in a sound-proof booth.
declarative
downstepped
yn-question
would be is
Agustín Gravano Speech Prosody 2008

16. Perception Study 2: Spoken Condition Experiment Design
Each session contained 60 tokens:
20 stimuli (only one stimulus from each set)
40 fillers (with all 3 contours: 13 dec, 13 ds, 14 yn)
Presented in a random order.
Participants rated the perceived certainty of each token on the same 5-degree Likert scale:
Very uncertain, Somewhat uncertain, Neither certain nor uncertain, Somewhat certain, Very certain.
Agustín Gravano Speech Prosody 2008

17. Perception Study 2: Spoken Condition Collected Data
30 participants (24 female, 6 male, mean age: 21.4)
600 data points:
Again, participants’ responses were:
1) Converted into numeric values.
2) Normalized using z-scores.
declarative
downstepped
yn-question
would be
100 is
Agustín Gravano Speech Prosody 2008

18. Perception Study 2: Spoken Condition Results
No interaction between Contour and Modality.
For all 3 contours: would be > is
For both modalities: downstepped > declarative >> yn-question
(All stat. significant.)
Agustín Gravano Speech Prosody 2008

19. Agustín Gravano Speech Prosody 2008
Conclusions
Epistemic would conveys...
Tentativeness.
A high degree of speaker certainty.
would be > is
However, the choice of intonational contour has a stronger impact on perceived certainty.
downstepped > declarative >> yn-question
Agustín Gravano Speech Prosody 2008

20. Agustín Gravano Speech Prosody 2008
Future Work
Production study
Before the textual perception study, the same 12 participants recorded each target utterance.
What contours were used to convey different degrees of speaker certainty?
Agustín Gravano Speech Prosody 2008

21. The Effect of Contour Type and Epistemic Modality on the Assessment of Speaker Certainty
Agustín Gravano1 · Stefan Benus2 · Julia Hirschberg1
Elisa Sneed German3 · Gregory Ward3
1 Columbia University
2 Univerzity Konštantína Filozofa
3 Northwestern University

22. Extra slide Sample Stimuli
A: I think the kids are tired of the water park. Maybe we should take them someplace else.
B: What's the Six Flags theme park located in Gurnee?
A: That {is, would be} Great America.
A: What a great party!
B: Yeah, but we're stuck cleaning up all the crap.
A: Hey, somebody left their iPod out on the floor.
B: That {is, would be} my roommate.
Agustín Gravano Speech Prosody 2008

23. Agustín Gravano Speech Prosody 2008
Extra slide Certainty Mean and StDev
Agustín Gravano Speech Prosody 2008

24. Agustín Gravano Speech Prosody 2008
Extra slide Fillers
token count
certainty mean ± stdev
downstepped
390
0.667 ± 0.435
declarative
0.605 ± 0.459
yn-question
420
1.299 ± 0.392
ANOVA: Significant difference (F(2, 1197) = , p≈0)
Tukey test: Difference is significant (95%) for ds>yn and dec>yn, and approaches significance for ds>dec.
Agustín Gravano Speech Prosody 2008

25. Extra slide Epistemic would: Form
Restricted to intransitive sentences:
SUBJECT + would + VERB + POST-VERBAL CONSTITUENT
Corpus study (Birner et al. ’07)
246 naturally-occurring tokens, from oral and written sources
Most frequent subjects are demonstratives (79%)
Nearly all verbs are be (98%)
Post-verbal constituent is typically, but not necessarily, a noun phrase.
Agustín Gravano Speech Prosody 2008