New evidence shows that babies
learning to understand language rely more heavily
than previously thought on patterns in the
language they hear, according to results presented
by a panel of scientists at the annual meeting of
the American Association for the Advancement of
The new data alter a long-established trend
that had swung the emphasis in language learning
research onto pre-programmed mechanisms built into
the human brain.
"The thinking for years had been that something
as complex as language could not be acquired with
fairly simple learning mechanisms that rely on
word frequency, associations between adjacent
words and other statistical phenomena," says
Rebecca Gomez, a presenter at the panel and an
assistant professor of psychology in The Krieger
School of Arts and Sciences at The Johns Hopkins
University. "But we now have new methods for
assessing learning in infants, and we've been able
to demonstrate that this type of learning is in
fact very strong."
Gomez uses exposure to artificial languages to
study language learning in infants and in adults.
"I'm interested in finding out how far
sensitivity to statistical information in language
can actually take an infant in the language
learning problem," Gomez says. "Artificial
languages allow me to eliminate any interference
from prior language learning and focus more
closely on what the learner is responding to."
Artificial language words have no meaning and
include such examples as "pel," "wadim," and
"jic." But Gomez organizes them to mimic
grammatical patterns in natural language.
"I'll find a regularity in natural language
that I think might be contributing to learning in
an important way, and I'll extract that and put it
into an artificial language in a very simplified
form," Gomez explains.
For her presentation at the AAAS meeting, Gomez
described her research into frequently occurring
words and sound groups.
Gomez investigated the conditions under which
infants switch the focus of their learning from
patterns involving adjacent words to patterns
involving words separated by other words in a
The two learning mechanisms, known respectively
as adjacent dependencies and long-distance
dependencies, are both important in language
"It's been shown in prior research that
adjacent dependencies are very useful in learning,
and might even be a kind of default mode for
language learners," says Gomez. "We set out to
test whether we could switch infants out of that
default mode by making long-distance learning more
Gomez exposed 18-month-old infants to
three-word strings of an artificial language. The
experiments took place in a booth with speakers on
the right and left of a central chair, where a
parent sat with the infant.
In the initial, training period of exposure,
the first and third words in the sequence were
linked and limited in variety to two pairs of
words. If the first word was "pel," the third word
was always "jic"; if the first word was "vot", the
third word was always "rud." The second word
varied, and was taken either from a small set of
words or from a very large word set.
After the training period, the infants were
re-exposed to a mixture of sentences that were
either "grammatical," agreeing with the rules
established in the training period that linked the
first and third words, or "ungrammatical,"
conflicting with the rules.
Infants who learned the distinction listened
longer to an "ungrammatical" burst of speech, as
if the "grammatical" stimuli were no longer
"What we actually found is that there's no
discrimination between 'grammatical' and
'ungrammatical' when the middle element only draws
on a small set of words," Gomez says, noting that
when the middle element word set is small, infants
can easily use the first word to predict the
second, or the second word to predict the third,
both of which are adjacent dependencies.
"With a large enough set size, actually 24, all
of a sudden infants and adults will learn the
dependency between the first and third words.
Twelve-month-olds do not show this ability,
suggesting it develops with age.
"This is an important demonstration, because it
shows that in addition to having access to
multiple learning mechanisms, infants can switch
to a new mechanism when the original mechanism is
no longer optimal," says Gomez.
Gomez and other infant researchers are
optimistic that they are seeing the first signs of
a shift in language learning research.
"We've always known that some aspects of
language had to be learned, rather than
pre-programmed, because there are differences in
languages," she says.
Scientists have recently discovered an
increasing number of statistical regularities in
language that infants can use to help learn
language, and a more even-handed view of the
balance between associative learning and
preprogrammed learning mechanisms built into the
brain is starting to emerge.
Gomez notes that she doesn't think the debate
between the two sides should be aimed at
eliminating one viewpoint, and that she feels both
sides have valid contributions to make to
science's understanding of how infants learn
Gomez's work is supported by the National
Science Foundation and the National Institutes of
Health. - By Micael C. Purdy
[Contact: Michael C.