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9 The Behavior System

With respect to social interaction, Kismet’s behavior system must be able to support the
kinds of behaviors that infants engage in. Furthermore, it should be initially configured
to emulate those key action patterns observed in an infant’s initial repertoire that allow
him/her to interact socially with the caregiver. Because the infant’s initial responses are often
described in ethological terms, the architecture of the behavior system adopts several key
concepts from ethology regarding the organization of behavior (Tinbergen, 1951; Lorenz,
1973; McFarland & Bosser, 1993; Gould, 1982).
Several key action patterns that serve to foster social interaction between infants and
their caregivers can be extracted from the literature on pre-speech communication of infants
(Bullowa, 1979; de Boysson-Bardies, 1999). In chapter 3, I discussed these action patterns,
the role they play in establishing social exchanges with the caregiver, and the importance
of these exchanges for learning meaningful communication acts. Chapter 8 presented how
the robot’s homeostatic regulation mechanisms and emotional models take part in many of
these proto-social responses. This chapter presents the contributions of the behavior system
to these responses.

9.1 Infant-Caregiver Interaction

Tronick et al. (1979) identify five phases that characterize social exchanges between
three-month-old infants and their caregivers: initiation, mutual-orientation, greeting, play-
dialogue and disengagement. As introduced in chapter 3, each phase represents a collection
of behaviors that mark the state of the communication. Not every phase is present in every
interaction, and a sequence of phases may appear multiple times within a given exchange,
such as repeated greetings before the play-dialogue phase begins, or cycles of disengage-
ment to mutual orientation to disengagement. Hence, the order in which these phases appear
is somewhat flexible yet there is a recognizable structure to the pattern of interaction. These
phases are described below:
• Initiation In this phase, one of the partners is involved but the other is not. Frequently
it is the mother who tries to actively engage her infant. She typically moves her face into
an in-line position, modulates her voice in a manner characteristic of attentional bids, and
generally tries to get the infant to orient toward her. Chapters 6 and 7 present how these
cues are naturally and intuitively used by naive subjects to get Kismet’s attention.
• Mutual Orientation Here, both partners attend to the other. Their faces may be either
neutral or bright. The mother often smoothes her manner of speech, and the infant may
make isolated sounds. Kismet’s ability to locate eyes in its visual field and direct its gaze
toward them is particularly powerful during this phase.

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