別紙41 (課程博士(英文))Date of submission (month day, year)

January 8小,2021

Department ofComputer Science andStudentlD NumberEngineering
Ppljcant's nameMichio okada

D143364
SuperV玲orsYusaku Nishiwald

Tetsuto Minami

Abstract (Doctor)
Tide oflhesis

Cooperative lnteractions Generated by h〕completeness in Robots' utterance

Approx、 80o words
The conversation has alw'ays got attention as a way for people to interact W北h system
S naturaⅡy.1mprovements in machine learning have made it possible for systems to understand human speech and human intentions. Therefore, systems such as smart spe
akers have become commonplace.1t is important to clarify the role of peop]e and syst

ems. The basis of the interaction is that the person speaks commands, and the system understands them. The system has focused on specializing 北S functions on an individual, such as recognizing speech and understanding intention of one person. However,
Mikhail Bakhtin mentioned that incompleteness is crucialin interacting with others,beyond conveying information. The incompleteness is a factor that a110ws the speakerto give the other person a new interpretation of part of the text. He said that incomp
Ieteness is a chance to create new meanings with them' According to Lotman, the info
rmation function of conversation and relationship、building function are not two separate things. For Human、computer conversation development, it is necessary to evolve theSystem conversation discussing the relationship・building function that involves a person, aimin宮 at conversation created with others. This study tested a method to prepare

for ambiguity, which has not been discussed and examined its effects.
First, we investigated the structure of speech in asymmetrical relationships between people and tbe practice of eliciting others' participation in conversations. we could see
the practices as other、initiated repairs and fishing、devices that encourage others' parti
Cipation in our daily conversations. For example, sociolin牙Uistic science described te11ing part of the story as a trigger to e]icit particlpation from those who have more respo
nsibi1北y.1n this study, we developed an "incomplete utterance strategy" in which therobot's speech is made lacking by removing additional pieces of information from its sPeech. The possibilities and effects of this speech strategy were investigated through three experiments.
Then, to investigate the validity of the incomplete utterance method, two strate今ies weretested、＼入le compared human behaviors between tw'o conditions, one semantica11y incomplete
Utterance and structuraⅡy incomplete utterance in human"robot conversation. The results

Showed that people increased their responses to the semantica11y incomplete robots throughactive participation in the conversation (questions, the introduction of new content related tothe conversation). Next, we examined what impressions were obtained from conversations
between humans and incomplete utterance robots. we used two of the most averageinteractions from the last experiment. we asked for new participants to evaluate the twoConversations. The results showed that participants perceived conversations W北h humans
and semantica11y incomplete utterance robots as cooperative. Fina11y,1 tackled the question:
Can an incomplete utterance elicit human involvement? we analyzed whether incomplete
Utterances elicit human participation in terms of changes in participation attitudes. AmuHi・party conversation was set up to analyze the changes in participation a此北Ude. Den
reported it is easier to change participation in a multi、party conversation than in a one'to、oneConversation. The experiment set up a multi、party conversation between a speaker robot, aIistener robot, and a participant、 The participants could choose to explain with the speaker
robot or listen with the listener robot、 we compared impressions and behaviors between theSemanticaⅡy incomplete utterance robot and the fU11y explaining robot. Results showed thatPeople increased their participation as the speaker with incomplete utterance robot.
Furthermore, they decreased their participation as the listener also. Besides,北 Was
Confirmed if the robot spoke incompletely, but participants joined the conversation, the rate
Of information transfer is estimated the same as the fU11y explained robot. However, thisStudy found that this incomplete utterance method had limitations.1t requires the speaker
robot to select a person as the next speaker directly. The in〕pression showed that althoU牙hParticipants increased their speech amount with incomplete utterance robot, they did not feel
Iike they were explaining together, which is a subject for future research.
We tested the incomplete utterance robot through three experiments.1t was confirmedthat the robot's incompleteness changes human behavior and participation attitude w
hen the robot tries to engage directly with a person. The result also showed that com
munication efficiency does not change if humans participate, even if the robot fa11S sh
Ort of words. SO,北 is possible to use this techn010gy as an interaction technique to el
icit human participation. However, this study's implementation was not enough to disc
USS C011aborative actions.1t wi11 be necessary to examlne the model for long、term impl
ementation in the future.

In recent years, robots that do not speak Japanese at a11 0n purpose have been
Commercialized and are gaining popularity in Japan. A robot that conveys information
accurately and has space for people to interact wi11 Continue to attract a此ention in the future.
This study proposed a new conversational design, which is speech incompleteness. weinvestigated its effects and limitations. This result may contribute to the engineering field'S
development as a basis for the next generation of interaction techn010gy forhuman、interactive systems.