Page 53 - Designing Sociable Robots

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34 Chapter 3

exaggerations typical of infant-directed speech (especially when communicating praise,
prohibition, soothing, or attentional bids) are particularly well-matched to the innate af-
fective responses of human infants (Fernald, 1989). This allows a caregiver to readily use
either his voice or face to cause the infant to either relax or become more vigilant in certain
situations, and to either avoid or approach objects that may be unfamiliar (Fernald, 1993).
Given the number of important and novel situations that human infants encounter (which do
not result in immediate pain or act as some other innate reinforcer, such as food), expressive
feedback plays an important role in their social and behavioral development.

Regulating arousal In addition to influencing the infant’s attention and affective state,
a caregiver is also careful to regulate the infant’s arousal level. She may adopt a staccato
manner of speech or use larger, faster movements to arouse him. Conversely, she uses sooth-
ing vocalizations and slower, smoother movements to relax him. Maintaining an optimal
level of arousal is important, since performance and learning depend upon the infant being
suitably alert, attentive, and interested in the situation at hand. Indeed, a caregiver expends
significant effort in keeping her infant at a moderate level of arousal, where he is neither
under-stimulated nor overwhelmed by the events facing him (Kaye, 1979).

Balancing agendas During instructional interaction, the caregiver allows her infant to
take the lead but shapes his agenda to meet her own. To accomplish this, the caregiver often
flashes to where her infant is, and then attempts to pull his behavior in the direction she
wants him to go. This agenda-shaping process can be seen when a caregiver imitates her
infant. This is not simply a matter of mimicry. Instead, the caregiver employs a number of
imitative strategies to shape and direct her infant’s behavior with respect to her own. Kaye
(1979) identifies three distinct strategies. First, maximizing imitation further exaggerates
the infant’s behavior. For instance, if the baby opens his mouth, she will open her mouth in
an exaggerated manner to encourage him to open his wider. Alternatively, she may employ
minimizing imitation to lessen the infant’s behavior. For example, if baby begins to make a
cry face, she responds with a quick cry face that immediately changes to a happy expression.
She may also employ modulating imitation to shape his behavior. For instance, when a baby
whines “waaah,” the caregiver responds with the same whine but then softens to a soothing
“awwww.” Hence, it is often the case that the caregiver’s imitation of her infant is motivated
by her agenda for him.

Introducing repetition and variation The caregiver frequently repeats movements and
vocalizations as she engages her infant, but she is also very creative in introducing variations
about a theme. According to Stern (1975), repetitive presentations of this nature are optimal
for holding the infant’s attention and establishes a good learning environment for him.
Sometimes she presents several nearly identical acts or vocalizations in a row, separated by