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128 Chapter 9

• Greeting Both partners attend to the other as smiles are exchanged. Often, when the baby
smiles, his limbs go into motion and the mother becomes increasingly animated. (This is
the case for Kismet’s greeting response where the robot’s smile is accompanied by small
ear motions.) Afterwards, the infant and caregiver move to neutral or bright faces. Now
they may transition back to mutual orientation, initiate another greeting, enter into a play
dialogue, or disengage.

• Play Dialogue During this phase, the mother speaks in a burst-pause pattern and the
infant vocalizes during the pauses (or makes movements of intention to do so). The mother
responds with a change in facial expression or a single burst of vocalization. In general, this
phase is characterized by mutual positive affect conveyed by both partners. Over time the
affective level decreases and the infant looks away.
• Disengagement Finally, one of the partners looks away while the other is still oriented.
Both may then disengage, or one may try to reinitiate the exchange.

Proto-Social Skills for Kismet
In chapter 3, I categorized a variety of infant proto-social responses into four categories
(Breazeal & Scassellati, 1999b). With respect to Kismet, the affective responses are impor-
tant because they allow the caregiver to attribute feelings to the robot, which encourages
the human to modify the interaction to bring Kismet into a positive emotional state. The
exploratory responses are important because they allow the caregiver to attribute curiosity,
interest, and desires to the robot. The human can use these responses to direct the interac-
tion toward things and events in the world. The protective responses are important to keep
the robot from damaging stimuli, but also to elicit concern and caring responses from the
caregiver. The regulatory responses are important for pacing the interaction at a level that
is suitable for both human and robot.
In addition, Kismet needs skills that allow it to engage the caregiver in tightly coupled
dynamic interactions. Turn-taking is one such skill that is critical to this process (Garvey,
1974). It enables the robot to respond to the human’s attempts at communication in a
tightly temporally correlated and contingent manner. If the communication modality is facial
expression, then the interaction may take the form of an imitative game (Eckerman & Stein,
1987). If the modality is vocal, then proto-dialogues can be established (Rutter & Durkin,
1987; Breazeal, 2000b). This dynamic is a cornerstone of the social learning process that
transpires between infant and adult.

9.2 Lessons from Ethology

For Kismet to engage a human in this dynamic, natural, and flexible manner, its behavior
needstoberobust,responsive,appropriate,coherent,anddirected.Muchcanbelearnedfrom