Gradual development of human-agent social relationship
Satoshi V. Suzuki (ssv@ntt.dis.titech.ac.jp)
DCISS, IGSSE, Tokyo Institute of Technology; J2–53, 4259 Nagatsuta
Midori-ku, Yokohama 226–8502 Japan

Hideaki Takeda (takeda@nii.ac.jp)
National Institute of Informatics; 2–1–2, Hitotsubashi
Chiyoda, Tokyo 101–8430 JapanTo maintain sound social relationships between people and social actors including robots, embodied agents,and computers, both parties in any relationship should
continue to have equal social positions. In other words,
the social actor should serve as the human’s “teammate” (Fogg, 2003) and not be thought of as a “slave.”
To enable the social actor to remain the human’s “teammate,” the human and the social actor should communicate with an appropriate amount and quality of information. That is, the social actor should not do such things
as behave embarrassingly, make the human interactant
think more deeply, or make him/her speculate what itreally intends. For example, designing a robot is only toobey commands from the interactants should be avoided.
The human interactant and the social actor should cooperate to accomplish the same task by sharing roles inthe task. In this article, a model of human-robot social
relational development is suggested. This model specifies what kind of information an embodied agent should
offer to the interactant. The process of human-agent relational development through human-agent interactionis also examined, with a view to gearing interactions toward developing positive relationships.
Human-agent relationships should develop gradually.
Human social relationships between two people develop
with consideration of their existing closeness (Knapp &Vangelisti, 2005). For example, a person will communicate in a conventional way with others upon meetingfor the first time (“initiating” stage of interaction), but
once he/she opens up to the others, he/she chooses toshow friendliness when communicating with them (“experimenting” stage of interaction). In this process, theperson is always paying attention to the social relationship between himself/herself and the others. Similarly,
an embodied agent should distinguish the interaction
style with close interactants from that with strangers. In
fact, in a psychological experiment of a human-computersocial interaction study, participants preferred a gradual way of human-computer relationships to an abrupt
way of developing them (Moon, 2000). This result suggests that the principle of gradual relationship development can be applied to human-robot interaction design.
Through such a gradual relationship development, aninteractant should find a novel viewpoint from a social
actor and brush up his/her own thought with the socialactor.
Another basis of the principle of gradual human-agent

relationship development is human cognitive structure.
People often behave as if they act according to a script,that is, they often cause action based on “social scripts”
without consideration (Langer, Blank, & Chanowitz,1978) until they are aware that they should consider
what happens around themselves. When a person communicates with others in the “initiating” stage, he/shewill talk to others in a script-like, conventional way without trying to discover unknown information about others in most cases. In this case, the person does nothave to worry about what to ask others. Then he/shewill start asking others questions about unknown information about them when the stage of human interaction switches to the “experimenting” stage. To ask suchquestions, the person should consider whether the questions are suitable for the others to ask in this situation,and this consideration should be cognitive burden for
him/her. In this article, the situation that people should
consider what happens around themselves and robots
is defined as the threshold of consideration, since suchconsideration often make the human-robot relationshipworse until the interactant’s credibility for the robot is
not enough. Sundar and Nass (2000) discovered thisthreshold of consideration in human-computer interaction. In the experiment in their study, participants weretold that they were interacting either with a computer
itself or with a human interactant (e.g., a programmer oran informant over the network). The participants preferred interacting with the computer itself to considering
the human interactant while interacting with the computer. This implication gives another aspect to Imaiand Narumi (2005). In their study, a humanoid robot
gave a participant a chocolate and a bottle of tea, eitherwith telling them that these were delicious, or without
telling so. As a result, the participants who were told by
the robot that the chocolate and the tea were delicious
tended to have anything that the robot recommended,
but those who were not told so were not likely to do so.
They concluded that the interactants read the robot’s“mind” when the robot told them about preference of acertain item. However, it is possible to explain their finding by saying that the participant unconsciously obeyed
the “social script” that people unconsciously tend to behave based on others’ preference (Cialdini, 2001). Nevertheless, if the interactant’s judgment of the credibilityof the robot is high enough because of much interaction between them, such attempts of the robot to inter-act with him/her beyond the threshold of consideration
cause strong closeness between the interactant and therobot.
In this study, the influence of “mind-reading” of anembodied agent was investigated through a psychological experiment. As a study of interaction between ahuman interactant and a social actor, the argument ofsocial response to the embodied agent should contributeto the human-robot social interaction design. A thoughtballoon emitted from the embodied agent for the human interactant to input its “mind” was focused on,since the thought balloon is a universal expression toexpress what a character thinks without utterance (Harrison, 1981). Through the comparison among three situations — the situation in which a blank thought balloon
appeared, the situation in which a blank speech balloon
appeared to let a participant guess what the embodied
agent would say, and the situation in which no blank balloon appeared — the influence of “mind-reading” to anembodied agent was examined. Two competing agents,agent A and agent B, appeared to help the participant
accomplish a task and then he/she evaluated the qualityof their help. Before the evaluation, when agent A persuaded the participant to evaluate it higher than agent
B, agent B emitted a blank balloon, either for speech or
for thought, or answered for agent A in accordance withexperimental conditions. Participants were assigned either of these conditions. Finally, the content of thethought balloon filled in by the participant was longer,and depicted agent B’s “mind” more intently than did
the content of the speech balloon. Thus, despite theblank thought balloon served to induce the participant
to read agent B’s “mind,” the participants who filled in
the blank thought balloon gave agent B’s help a lower
evaluation than did those who filled in the blank speechballoon. Besides, the participant who filled in the blankspeech balloon evaluated agent B higher than did thosewere not required to fill in any blank balloon, althoughno significant difference was not observed between them.
The result of the psychological experiment implies
that requiring abrupt “mind-reading” to the social actor
can damage the social relationship with the interactant.
Filling in the blank thought balloon emitted from an embodied agent without enough prior interaction with thatagent seems to be beyond the threshold of consideration
for the interactant. While the situation — that agent
A and agent B were competing with each other — may
have had some influence on the relationship, considering the argument on threshold of consideration, abrupt“mind-reading” induced by the blank thought balloon
emitted from the embodied agent weakened the social
relationship between the human interactant and the embodied agent. Although the prompt to read robot’s“mind” should be different from the agent’s, the situation in which an interactant needed to abruptly readthe “mind” of the robot seems to have been harmful tothe human-robot social relationship. Moreover, the participants who filled in the blank speech balloon evaluatedagent B’s help higher than did those in other conditions.
This result suggests that filling in the blank speech bal-loon functioned as human-agent interaction under thethreshold of consideration in this experimental environment. However, the experiment did not examine whether
the explicit inspection of the agent’s thought after thisinteraction promotes or damages the human-agent socialrelationship. The change of the threshold of consideration in human-agent interaction should be taken into
account with empirical approaches.
This study investigated the process of the gradual development of human-agent social relationships. To examine this process, the psychological experiment of interaction between a participant and an embodied agent wasconducted to inspect the influence of “mind-reading” by
a human interactant to a social actor on their relationship. The experimental results suggest requiring that
abrupt “mind-reading” to the embodied agent negatively
influences the interactant. A gradual way of encouraging human interacts to read the “mind” of the embodied
agent should thus be investigated further. This would
contribute to the gradual development of social relationships between human interactants and social actors.

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