Infants who are raised in bilingual homes learned two similar-sounding
words in a laboratory task at a later age than babies who
are raised in homes where only one language is spoken. This
difference, which is thought to be advantageous for bilingual
infants, appears to be due to the fact that bilingual babies
need to devote their attention to the general associations
between words and objects (often a word in each language)
for a longer period, rather than focusing on detailed sound
information. This finding suggests an important difference
in the mechanics of how monolingual and bilingual babies learn
These findings are from new research conducted at the University
of British Columbia and Ottawa. They appear in the September/October
2007 issue of the journal Child Development.
Immigration, official language policies, and changing cultural
norms mean that many infants are being raised bilingually.
Because nearly all experimental work in infant language development
has focused on children who are monolingual, relatively little
is known about the learning processes involved in acquiring
two languages from birth.
The researchers sought to determine whether the demands of
acquiring more sounds and words lead to differences in language
development. An important part of language development is
the ability to pay attention to native speech sounds to guide
word learning. For example, English learners expect that the
nonsense words bih and dih refer to
different concepts because b and d
are different consonant categories in English. By 17 months
of age, monolingual English infants use native-language speech-sound
differences to guide them as they learn words. Do bilingual
infants show a similar developmental pattern?
The study revealed that bilingual infants follow a slightly
different pattern. Researchers tested bilingual children ages
14, 17, and 20 months on their ability to associate two words
that differed in a single consonant sound with two different
objects. Experiment 1 included a heterogeneous sample of bilingual
babies (i.e., those exposed to English and another language).
Experiment 2 tested two homogeneous groups of bilingual infants
(English-French and English-Chinese). In both experiments,
infants were repeatedly presented with a crown-shaped object
that was called bih and a molecule-shaped object
called dih. They were then tested on their ability
to notice a switch in an objects name (for example,
the molecule-shaped object being called bih instead
of dih). In all of the groups, the bilingual infants
failed to notice the minimal change in the objects name
until 20 months of age, whereas monolingual infants noticed
the change at 17 months.
This later use of relevant language sounds (such as consonants)
to direct word learning is due to the increased demands of
learning two languages, the researchers suggest. Ignoring
the consonant detail in a new word may be an adaptive tool
used by bilingual infants in learning new words. Outside the
laboratory, there is little cost to overlooking some of the
consonant detail in new words, as there are few similar-sounding
words in infants early vocabularies. By paying less
attention to the detailed sound information in the word, bilingual
infants can devote more cognitive resources to making the
links between words and objects.
Extending this approach to word learning for a few months
longer than monolinguals may help bilinguals keep up
with their peers. Indeed, previous research has shown that
bilinguals and monolinguals achieve language-learning milestones
(such as speaking their first word) at similar ages and have
vocabularies of similar sizes when words from both languages
are taken into account.
Through studies with bilingual infants, we can gain
a deeper understanding of language development in all infants,
according to Christopher T. Fennell, assistant professor of
psychology at the University of Ottawa and the lead author
of the study. In addition, the findings emerging from
such studies will have practical implications for parents
who are raising their children in a bilingual environment
by revealing how young bilinguals acquire language.