Page 48 - Designing Sociable Robots

breazeal-79017 book March 18, 2002 13:58

Insights from Developmental Psychology 29

as the infant’s capabilities improve and become more diverse, there is still an environment
of sufficient complexity for him to develop into.
For instance, the infant’s own physically immature state serves to limit his perceptual and
motor abilities, which simplifies his interaction with the world. According to Tronick et al.
(1979),infantsperceiveeventswithinanarrowerperipheralfieldandashorterstraight-ahead
space than adults and older children. Further, the infant’s inability to distinguish separate
words in his caregiver’s vocalizations may allow him to treat her complex articulated phrases
as being similar to his own simpler sounds (Bateson, 1979; Trehub & Trainor, 1990). This
allows the infant to participate in proto-dialogues with her, from which he can begin to
learn the tempo, intonation, and emotional content of language long before speaking and
understanding his first words (Fernald, 1984). In addition, the infant is born with a number of
innatebehavioralresponsesthatconstrainthesortsofstimulationthatcanimpingeuponhim.
Various reflexes (such as quickly withdrawing his hand from a painful stimulus, evoking
the looming reflex in response to a quickly approaching object, and closing his eyelids
in response to a bright light) serve to protect the infant from stimuli that are potentially
dangerous or too intense. According to Brazelton (1979), when the infant is in a situation
where his environment contains too much commotion and confusing stimuli, he either cries
or tightly shuts his eyes. By doing so, he shuts out the disturbing stimulation.
To assist the caregiver in regulating the intensity of interaction, the infant provides her
with cues as to whether he is being under-stimulated or overwhelmed. When the infant
feels comfortable in his surroundings, he generally appears content and alert. Too much
commotion results in an appearance of anxiety, or crying, if the caregiver does not act to
correct the environment. In contrast, too much repetition causes habituation or boredom
(often signaled by the infant looking away from the stimulus). For the caregiver, the ability
to present an appropriately complex view of the world to her infant strongly depends on
how good she is at reading her infant’s expressive and behavioral cues.
Adults naturally engage infants in appropriate interactions without realizing it, and care-
givers seem to be instinctually biased to do so, varying the rate, intensity, and quality of their
activities from that of adult-to-adult exchanges. Tronick et al. (1979) state that just about
everything the caregiver does is exaggerated and slowed down. Parentese (or motherese)is
a well-known example of how adults simplify and exaggerate important aspects of language
such as pitch, syntax, and pronunciation (Bateson, 1979; Hirsh-Pasek et al., 1987). By doing
so, adults may draw the infant’s attention to salient features of the adult’s vocalizations and
hold the infant’s attention (Fernald, 1984). During playful exchanges, caregivers are quite
good at bringing their face sufficiently close to their infant, orienting straight ahead, being
careful to move either parallel or perpendicular to the infant, and using exaggerated facial
expressions to make the face more readable for the infant’s developing visual system.