Agustín Gravano1 · Stefan Benus2 · Julia Hirschberg1

Elisa Sneed German3 · Gregory Ward3

11 Columbia University Columbia University22 Univerzity Konštantína Filozofa Univerzity Konštantína Filozofa

33 Northwestern University Northwestern University

The Effect of Contour Type andEpistemic Modality on the

Assessment of Speaker Certainty

Agustín Gravano Speech Prosody 2008 2

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

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

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 ConditionTask 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 knockson 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 ConditionExperiment 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 ConditionComputer Interface

Agustín Gravano Speech Prosody 2008 9

Perception Study 1: Textual ConditionCollected 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 1Neither 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 ConditionResults

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

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 ConditionTask 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 ConditionComputer Interface

Agustín Gravano Speech Prosody 2008 14

Perception Study 2: Spoken ConditionIntonational Contours

Simple declarative contour (H*) H* L- L%

Downstepped contourH* !H* (!H*) L- L%

Yes-no-question contour(L*) L* H- H%

Agustín Gravano Speech Prosody 2008 15

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

Perception Study 2: Spoken ConditionMaterials

Agustín Gravano Speech Prosody 2008 16

Perception Study 2: Spoken ConditionExperiment 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 ConditionCollected 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 100 100 100

is 100 100 100

Agustín Gravano Speech Prosody 2008 18

Perception Study 2: Spoken ConditionResults

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

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

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 Gravano1 · Stefan Benus2 · Julia Hirschberg1

Elisa Sneed German3 · Gregory Ward3

11 Columbia University Columbia University22 Univerzity Konštantína Filozofa Univerzity Konštantína Filozofa

33 Northwestern University Northwestern University

The Effect of Contour Type andEpistemic Modality on the

Assessment of Speaker Certainty

Agustín Gravano Speech Prosody 2008 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

Extra slide

Certainty Mean and StDev

Agustín Gravano Speech Prosody 2008 24

Extra slide

Fillers

tokencount

certainty mean ± stdev

downstepped 390 0.667 ± 0.435

declarative 390 0.605 ± 0.459

yn-question 420 1.299 ± 0.392

ANOVA: Significant difference (F(2, 1197) = 2778.2, 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.