Initiative in Dialogue (draft)
Mark Core
An Informal Definition
• OED.com: to take the initiative: to take the lead, make
the first step, originate some action
• Sometimes referred to as “control”
• dialogue initiative identifies who is leading the dialogue
at any given point
Why do people study initiative?
• Dialogue System Builders
• for some applications, system may need to reason
about whether to take the initiative
• systems need to take and give away initiative smoothly
like humans
• system acts differently when it does and does not have
initiative
• Linguists
• open question: what factors influence when dialogue
participants take initiative
Outline
• Defining and Annotating Initiative
• Discourse Structure
• Whittaker and Stenton
• Strayer and Heeman
• Linell et al.
• What is Known about Initiative
• Initiative and Current Dialogue Systems
• Going Beyond Initiative
Discourse Structure and Initiative
• “dialogue initiative ... tracks the lead in determining the
current discourse focus” (Chu-Carroll and Brown 1997,
p. 263)
• topic-based segmentation – who initiated the topic.
Grosz and Sidner (1986)
• dialogue moves – who produced an initiating move.
Grosz and Sidner (1986)
• Discourse grammar (syntax)
• Discourse => Discourse_Segment+
• Discourse_Segment => utterance+
• Discourse grammar (semantics)
• there is one unique ‘foundational’ purpose to the
dialogue and each discourse segment
• meant to be recognized by listener
• the discourse segment purposes (DSPs) support the
discourse purpose
• utterances support discourse support the DSP
Structural Relations
• dominance: discourse is hierarchical. one DSP may be
intended to provide part of the satisfaction of another
• satisfaction-precedence: order of DSPs may be significant
DS1
E: First you have to remove the flywheel....
loosen the two allen head setscrews...
DS2
A: I can only find one screw. Where’s the other one?
....
A: I can find them both now
DS3
E: Use the wheelpuller. Do you know how to use it?
...
E: The wheel should slide off
[p. 186]
Attentional State
• focus spaces – contain salient entities (mentioned
explicitly or implicitly)
• Entities could be properties, objects, relations, as well as
the discourse segment purpose
• Let’s just look at objects
Focus Space Stack
DS1
DS1
E: First you have to remove the flywheel....
loosen the two allen head setscrews...
DS2
DS2
A: I can only find one screw. Where’s the
other one?
....
A: I can find them both now
DS3
DS3
E: Use the wheelpuller. Do you know
how to use it?
...
E: The wheel should slide off
screw1
wheel
screw
puller2
flywheel
screw1
screw2
FOCUS SPACE STACK
Dialogue Moves and Games
• Dialogue Moves
• also called speech acts or dialogue acts
• capture intention behind an utterance
• examples
• initiating: e.g., command, statement, question
• responding: acknowledgement, answer, accept, reject
• Dialogue Games
• start with an initiating move and end when the goal of that
move is accomplished or abandoned
• games can be nested
Dialogue Games Example
[1] T:
[2] S:
[3]
[4] T:
[5] S:
[6] S:
[7] T:
[8]
[9]
Do you still believe [your answer]?
I suppose not.
But doesn’t I=V/R?
Yes. That is true.
because V=IR
So why doesn‘t I = 75 / the resistence?
If P=IV, then you know that I = P/V.
I can only equal P/R if R=V.
Do you have a reason to believe that
R=V?
[10] S: no
Complimentary Approaches
• Can group dialogue games based on topic
• In tutoring ‘how to measure current’ we can group
dialogue games around the topics:
• preparing the circuit (turn off power and break circuit)
• connect leads across break (+ and – leads must be
connected correctly)
Whittaker and Stenton (1988)
• Simpler procedure for initiative assignment
• Use four dialogue moves
• Assertions – “Declarative utterances used to state facts”
• Commands
• Questions
• Prompts – “Utterances which did not express propositional
content, such as Yeah, Okay, Uh-huh”
• Initiative assignment
• Assertion – speaker has initiative unless responding to a
question
• Command – speaker has initiative
• Question – speaker has initiative unless responding to a
question or command
• Prompt – hearer has initiative
Walker and Whittaker (1990)
• “third person and one anaphors cross [these] boundaries
extremely rarely” p. 73-74
• discourse segment boundaries marked by initiative
changes
Strayer and Heeman (2001)
• Compared initiative (annotated with Whittaker and
Stenton’s rules) to dialogue structure (as defined by
Grosz and Sidner)
• Whittaker and Stenton rules are more fine-grained than
Grosz and Sidner segmentation
• Forward Acknowledgments: listener takes initiative by
completing the speaker’s utterance
• Other-Contributions: listener and speaker building
utterances together
• Usually initiative goes back to the original speaker after
the interjection
Linell et al. (1988)
• each utterance is ranked based on how much “they can
be regarded as governing or steering the ensuing
dialogue and as being governed or commanded by the
preceding dialogue” p. 419
• highest rank (6): not a response in any way but requires
a response from the listener
• lowest rank (2): invite no response and give no more
information than required
Whittaker and Stenton (again)
• Whittaker and Stenton (1988)
• benefits
•
•
•
•
relatively simple to annotate
correlates well with discourse structure
gives us insight into “taking” and “giving away” initiative
extendable (consider additional dialogue moves)
• drawbacks
• does not account for answers giving more information than
requested
• never considers clarification requests as taking initiative
• redundant if you know discourse structure
Outline
• Defining and Annotating Initiative
• Discourse Structure
• Whittaker and Stenton
• Strayer and Heeman
• Linell et al.
• What is Known about Initiative
• Initiative and Current Dialogue Systems
• Going Beyond Initiative
Walker and Whittaker (1990)
• Distinguish between types of control shifts (i.e., speaker
2 takes initiative after...)
• Abdication: speaker1 utters a prompt signaling initiative
is released
• Repetition/Summary: speaker1 signals the end of their
contribution with a repetition or summary
• Interruption: speaker1 has not invited speaker2 to take
initiative
• Rationale: listener knows a relevant fact, listener detects
a problem in the speaker’s proposal, or listener finds the
utterance ambiguous
Walker and Whittaker (1990)
Finance
Support
Pump-Phone
Pump-Chat
Turns/Seg
7.49
8.03
15.68
11.27
Exp-Initiative
60%
51%
91%
91%
Abdication
38%
38%
45%
28%
Summary
23%
27%
7%
6%
Interrupt
38%
36%
48%
67%
Guinn (1996)
• used simulated conversations to argue that the most
efficient problem-solving dialogues are those where the
participant who knows the most about the current
subtask takes initiative
Distribution of Expert Initiative
Domain
Expert Control
Finance
60%
Computer Support
51%
Pump Repair
91%
TRAINS-93
39.5%
Airline
58.1%
Maptask
86.6%
Switchboard
59.9%
Socratic Tutoring
90%
Didactic Tutoring
79%
Initiative and Learning Gain
% Student Initiative
50
40
30
20
10
0
0
5
10
15
20
25
Learning Gain
Pearson’s r = -.0689, n=23, NS
30
35
40
Initiative Shifts
• Chu-Carroll and Brown (1997)
• Explicit cues
• Discourse cues
• silence, repetitions, prompts, questions, obligation
fulfilled
• Analytical cues
• invalid action/belief, sub-optimality, ambiguity
• Giving more information than requested
Factors affecting initiative
•
•
•
•
•
•
•
•
•
Individual or joint goals?
Collaborative or competitive task?
Distribution of knowledge/expertise
Complexity of task
Task-based roles
Social roles
Social projection (face)
Group discussion v. one-on-one
Mediation/modality
Outline
• Defining and Annotating Initiative
• Discourse Structure
• Whittaker and Stenton
• Strayer and Heeman
• Linell et al.
• What is Known about Initiative
• Initiative and Current Dialogue Systems
• Going Beyond Initiative
Horvitz (1999)
• email reading system (graphical) – based on the content
of the email should the system (1) bring up the calendar,
(2) ask the user first, (3) do nothing
• utility-based approach – penalties for interrupting user,
bringing up calendar unnecessarily, and reward for
bringing up the calendar when needed
Simple Speech-based Systems
• Here, initiative affects the system questions:
• system initiative: “What city do you want to leave from?”
• user initiative: “How may I help you?”
• initiative also affects how the system deals with extra
information
e.g., S: What city do you want to leave from?
U: LA on November 17th
• system initiative: ignores extra info
• mixed/user initiative: processes all information
• the major factor is speech recognition performance
Tutorial Dialogue Systems
• Tend to be system initiative although sometimes
students can ask questions about definitions: “What is a
CPU?”
• EDGE system (Cawsey 1989)
• if user question is related to a presentation goal, system
will request that the user wait
• Duke Programming Tutor (Keim et al. 1997)
• topics picked on basis of
•
•
•
•
•
believed student understanding
importance of topic
distance from current topic
how many times topic has been discussed
student interest
Outline
• Defining and Annotating Initiative
• Discourse Structure
• Whittaker and Stenton
• Strayer and Heeman
• Linell et al.
• What is Known about Initiative
• Initiative and Current Dialogue Systems
• Going Beyond Initiative
Tutorial Dialogue Systems
• (Core et al. 2003) study showed no relationship between
initiative and learning
• Shah (1997) found more student initiative in students’ first
sessions
• Graesser and Person (1994)
• in the first half of a course, found a negative correlation
between number of student questions and exam scores
• in second half of course, found a positive correlation
between exam scores and proportion of student questions
that were deep-reasoning and knowledge-deficit
questions
Task Initiative
• Who has initiative can be quite independent of what’s
happening with the task (e.g., putting together the water
pump, learning physics)
• (Chu-Carroll and Brown 97) & (Jordan and Di Eugenio
97)
• If the dialogue concerns a task, it is possible to lead the
dialogue but not contribute to the task
• Chu-Carroll and Brown separate these ideas into
dialogue initiative and task initiative
Chu-Carroll and Brown Example
S: I want to take NLP to satisfy my seminar course
requirement
Who is teaching NLP?
A1: Dr. Smith is teaching NLP
A2: You can’t take NLP because you haven’t taken AI,
which is a prerequisite for NLP.
A3: You can’t take NLP because you haven’t taken AI,
which is a prerequisite for NLP. You should take
distributed programming to satisfy your requirement,
and sign up as a listener for NLP.
Simple Task Initiative
• MIMIC (Chu-Carroll and Nickerson 2000)
• simple spoken dialogue system (for movie
information)
• task initiative means system gives directions
• e.g., “Please say the name of the movie or theatre
or town you would like information about”
• task initiative means system makes suggestions
• e.g., “Terminator is not playing at <theatre>
Terminator is playing at <alternative theatre> at <time1>
• Mixed-initiative MIMIC system outperformed systeminitiative MIMIC (better user satisfaction and task
efficiency)
Chu-Carroll and Nickerson (2000)
• Mixed-initiative MIMIC reasons about cues
• TakeOverTask (user gives more info than requested)
• NoNewInfo
• InvalidAction/InvalidActionResolved
• AmbiguousAction/AmbiguousActionResolved
Future Work
• “Although a system needs to reason about how helpful it
needs to be, it is unclear whether this can be done
through a single variable [task initiative] that is tied to
dialogue initiative” (Strayer and Heeman p. 7 of pdf)
• How to apply this principle to more complex domains
such as tutoring
• student model contains all facts about domain
• student has task initiative if he demonstrates knowledge
of such a fact
• also if student recognizes their own error
• may want to model hints which to various degrees give
away the answer