Grounding and Repair

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Grounding and Repair

• Joe Tepperman
• CS 599 Dialogue Modeling
• Fall 2005

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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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Clark and Schaefers 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

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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?
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Types of Evidence

• Display B repeats As 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
  As presentation

strongest
Strongest?
Oblivious?
weakest
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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.

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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

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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 CS evidence
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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
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Previous Example

• DU1
• 1 initiateI 1
• 2 continueI 1
• 3 acknowledgeR F
• DU1 DU2
• 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
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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

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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?

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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
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System Design

• Two modules
• maintenance
• intention
• Conversation Control
• exchanges info between the modules
• determines grounding state
• weighs costs and benefits
• evaluates module performance reliability

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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

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Grounding Strategies
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Signal Failure
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Detecting Miscommunication Dybkjaer et. al. 1996
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GP6 Avoid obscurity of expression
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Detecting Verifying ASR Errors Krahmer et.
al. 2001
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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.
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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)
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Grounding Model for MACK