Babble Rousers 

Babies find their voice when given social push 

Eight-month-old infants utter more complex,
speech like sounds when their mothers encourage them
with well-timed touches and smiles rather than
with words offered as models
to imitate,
a new study finds.

This provides the first evidence 
hat nonverbal interactions
with caregivers shape babies'
vocal learning,
says psychologist Michael H. Goldstein of Franklin 
and Marshall College in Lancaster, Pa.

The power of maternal behaviors
to ramp up babies'
babbling corresponds
to the way certain bird species learn
to sing,
propose Goldstein and his coworkers Andrew P. King 
and Meredith J. West,
both of Indiana University in Bloomington."

This is a basic type of social learning,"
Goldstein asserts."

At 8 months of age,
kids may already make complex speech sounds occasionally,
but they produce them regularly in response
to [certain encouraging] interactions
with a caregiver."

The new findings,
slated
to appear in an upcoming 
Proceedings of the National Academy of Sciences,
support the view that learning language 
doesn't hinge solely on the ability
to imitate spoken sounds.

Goldstein's group studied 30 infants 
averaging 8 months of age and their mothers.

Each mother-child pair first played in a room stocked
with toys
for 10 minutes.

Then half the mothers were told
to respond immediately during the next 10 minutes
to a baby's vocalizations by smiling,
moving closer to the child,
and gently touching him or her - but not by talking.

The rest of the mothers were instructed through headphones
to react in the same ways,
but usually not right after a baby made sounds.

In those cases in which mothers timed their smiles and touches
with their babies'
vocalizations,
the infants' babbling almost instantly 
became more mature,
the scientists say.

Compared
with during the initial play period,
these babies enunciated substantially 
more syllables such as
"da"
and
"gu."

They also drew deeper breaths while vocalizing,
which improved their articulation 
of speech sounds and removed 
e nasal tone that many of them had at first.

During a final 10-minute stretch,
both groups of mothers played without restrictions
with their babies.

Those infants that had received nonverbal encouragements continued
to produce more syllables and more finely articulated speech sounds than their counterparts,
although all infants vocalized less frequently during this final phase.

Several songbird species exhibit a type of social learning that parallels the impact of mothers'
behavior on their babies'
babbling,
the researchers contend.

For instance,
in brown-headed cowbirds,
young males transform immature songs into polished form by heeding the nonsocial responses of adult females,
such as subtle wing movements.

The new findings reiterate how the social environment influences the use of language in infancy,
remarks psychologist Michael Orwen of Cornell University.

However,
it's not clear that a common mechanism underlies learning in songbirds and babies,
he says.

Because song learning is restricted
to male cowbirds instructed only by females,
the process may rely on a specialized procedure,
Owren says."

Goldstein's study is important because it puts more of the responsibility
for the infant's language learning on the caretakers,
rather than depending entirely on a special mechanism within the infant-imitation,"
says Indiana University psychologist Susan S. Jones. 

B. Bower