Grounding and Repair

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# Grounding and Repair - PowerPoint PPT Presentation

Grounding and Repair. Joe Tepperman CS 599 – Dialogue Modeling Fall 2005. Grounding. Establishing mutual belief Collaborative More than one active participant Acknowledgement Necessary for: Dialogue flow, theorem proving, etc. User modeling Repairing dialogue & ASR errors.

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### Grounding and Repair

Joe Tepperman

CS 599 – Dialogue Modeling

Fall 2005

Grounding
• Establishing mutual belief
• Collaborative
• More than one active participant
• Acknowledgement
• Necessary for:
• Dialogue flow, theorem proving, etc.
• User modeling
• Repairing dialogue & ASR errors
Clark and Schaefer’s Contribution Model (1989)
• Influential, but not practical
• Contributions in two parts:

Presentation Phase

• Contributor presents content, Partners try to understand it

Acceptance Phase

2. Contributor & Partners move towards a grounding criterion: mutual belief that the contributor was understood sufficiently

Assumptions
• Presentation Phase
• A assumes that B has understood u if B demonstrates some minimum evidence e or stronger
• Acceptance Phase
• B assumes A will believe he has understood u if A registers that B has demonstrated evidence e’

Requires acceptance of acceptance?

Types of Evidence
• Display: B repeats A’s presentation verbatim
• Demonstration: B demonstrates what he has understood
• Acknowledgement: B makes some sign that he has understood
• Initiate Next Contribution: B makes a relevant contribution
• Continued Attention: B shows he is satisfied with A’s presentation

strongest

Strongest?

Oblivious?

weakest

Where does the

presentation end?

Main Problem with the Model
• How to tell the current state for each utterance: presentation or acceptance phase?

A: Move the boxcar to Corning.

A: And load it with oranges.

B: Okay.

A: Move the boxcar to Corning.

B: Okay.

A: And load it with oranges.

B: Okay.

The Grounding Acts Model (Traum 1992)
• Collapses all different types of acceptance
• Single-utterance level grounding units
• Allows automatic recognition of a within-utterance grounding act
• No need to wait for the next phase to start before identifying completion of current one
Grounding Acts
• Initiate: Begin new content
• Continue: Add related content
• Acknowledge: Demonstrate or claim understanding
• Repair: Correct a perceived misunderstanding
• Request Repair
• Request Acknowledgment
• Cancel: Leave unit ungrounded

Includes all C&S “evidence”

State Transition Matrix

I: initiator R: responder

S: start F: grounded D: “dead” state

1: ack needed for grounding

2: repairI needed 3: ackI needed

4: repairR needed

Previous Example

DU1

1: initiateI 1

2: continueI 1

3: acknowledgeR F

DU1DU2

1: initiateI 1

2: acknowledgeR F

3: initiateI F 1

4: acknowledgeR F F

A: Move the boxcar to Corning.

A: And load it with oranges.

B: Okay.

A: Move the boxcar to Corning.

B: Okay.

A: And load it with oranges.

B: Okay.

DU: Discourse Unit

Open Problems with this Model
• Binary grounded/ungrounded decision
• No levels of “groundedness”
• Leaves the unit size unspecified
• Confusability of grounding acts
• e.g. repetition = acknowledgment, repair, or request for repair?
• Only well-suited for spoken language grounding
A More Complete Psychological Model
• How is a particular grounding act realized?
• How important is the grounding?
• How useful will it be to the system?
• What criteria are needed?
• How well will a particular act ground its intended content?
• And what is the opportunity cost of performing this act?
• Is it worth it?
Levels of Analysis: Quartet, Paek & Horvitz 2000
• Channel Level: attempt to open communication channel with some behavior
• Signal Level: behavior is intended as a signal
• Intention Level: understanding of semantic content occurs
• Conversation Level: a joint activity is proposed and responded to

lowest

highest

*All levels require coordination between speaker and listener

Signal & Channel level

Intention level

Conversation level

System Design
• Two modules:
• maintenance
• intention
• Conversation Control
• exchanges info between the modules
• determines grounding state
• weighs costs and benefits
• evaluates module performance & reliability
Benefits of this Design
• ASR can model probabilistic dependencies among levels
• Easier to pinpoint and fix problems in system understanding
• Models psychological strategies for grounding on lower levels first
• Flexibility in multiple domains: simply changing the intention module
Utterance Features
• System
• Implicit/Explicit question
• Number of verified slots
• Default assumptions: true?
• Number, type, and recurrence of errors
• User
• Length (in words)
• Answer to verification question?
• Ordinary word order?
• Confirmation/Disconfirmation markers
• Number of repeated, new, and corrected slots

When do you want to travel to Amsterdam?

So you want to travel to Amsterdam?

Date, time, destination, etc.

e.g. travel today

Human-labeled

I want to go to Amsterdam

Where I want to go is Amsterdam

Yes, no, yeah, nope, etc.

Nonverbal Grounding: Nakano et. al. 2003

Speaker/Listener

gP: gaze at partner

gM: gaze at map

gMwN: gaze at map & nod

UU: utterance unit (intonational)