[lit-ideas] Re: Amazing babies
- From: Robert Paul <rpaul@xxxxxxxx>
- To: lit-ideas@xxxxxxxxxxxxx
- Date: Sun, 27 May 2007 19:40:47 -0700
Recently, scientists have learned the following:
* At a few days old, infants can pick out their native tongue from
a foreign one.
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Science 25 May 2007:
Vol. 316. no. 5828, p. 1159
DOI: 10.1126/science.1137686
Brevia
Visual Language Discrimination in Infancy
Whitney M. Weikum,1* Athena Vouloumanos,2 Jordi Navarra,3,4 Salvador
Soto-Faraco,4,5 Núria Sebastián-Gallés,4 Janet F. Werker1
This study shows that 4- and 6-month-old infants can discriminate
languages (English from French) just from viewing silently presented
articulations. By the age of 8 months, only bilingual (French-English)
infants succeed at this task. These findings reveal a surprisingly early
preparedness for visual language discrimination and highlight infants'
selectivity for retaining only necessary perceptual sensitivities.
1 University of British Columbia, Vancouver, BC V6T 1Z4, Canada.
2 McGill University, Montreal, QC H3A 1B1, Canada.
3 Oxford University, Oxford OX1 3UD, UK.
4 Parc Científic de Barcelona, Universitat de Barcelona, 08028
Barcelona, Spain.
5 Institut Catatlà de Recerca i Estudis Avançats (ICREA), 08010
Barcelona, Spain.
* To whom correspondence should be addressed. E-mail: whitney@xxxxxxxxxxxx
Talking faces are among the most dynamic and salient stimuli available
to infants, and the facial movements accompanying speech influence adult
(1) and infant (2) speech perception. Recently it was reported that
facial speech information alone is sufficient for language
discrimination in adults (3). Although it is well established that young
infants can discriminate languages auditorily (4, 5), it is unknown
whether infants can discriminate languages visually. We examined whether
4-month-old infants can visually distinguish their native language
(English) from an unfamiliar language (French). Because exposure to
specific auditory and visual information in infancy is essential for
maintaining many early-appearing native language, musical, and face
perception sensitivities (6--10), we compared monolingual English
infants to French-English bilingual infants at 6 and 8 months.
Discrimination was tested by using silent video clips of three bilingual
French-English speakers reciting sentences in each language. Every trial
contained a video clip of a different sentence by one speaker in one
language (for example, movies S1 and S2). The infants (n = 36) were
presented with video clips from one of the languages until their looking
time declined to a 60% habituation criterion. Test trials using the same
speakers but different sentences from the other language were shown to
examine whether the infants' looking time had increased, indicating that
they had noticed the language change. The test trials where the language
was switched were compared with a control condition (n = 36) for which
the test trials were always different sentences but in the same language
as the habituation trials (11). A repeated-measures analysis of variance
(ANOVA) including age (4, 6, or 8 months), condition (language switch
versus control), and trial (habituation versus test) revealed only a
significant three-way interaction [F(2, 66) = 3.71, P < 0.05]. Simple
main effects analyses showed that the infants looked significantly
longer at the language switch test trials (Fig. 1A), compared with the
control trials, at 4 months [F(1, 22) = 4.70, P < 0.05] and 6 months
[F(1, 22) = 4.19, P = 0.05] but not at 8 months [F(1, 22) = 1.18, P = 0.29].
Figure 1 Fig. 1. Mean looking time in seconds to silent talking
faces. The y axis represents infant looking time; the x axis represents
the trials that the infant was shown (final habituation trials and test
trials). Error bars represent the standard error of the mean. (A)
Experimental (language switch) and control (language same) conditions
for monolingual infants at 4, 6, and 8 months. (B) Experimental
conditions for monolingual [replotted from (A)] and bilingual infants at
6 and 8 months. [View Larger Version of this Image (13K GIF file)]
The finding that infants can visually discriminate their native language
from an unfamiliar language at 4 and 6 months but not at 8 months
parallels declines in performance seen in other perceptual domains.
Indeed, across the first year of life, infants' performance declines on
the discrimination of nonnative consonant and vowel contrasts (6, 7),
nonnative musical rhythms (8), cross-species individual faces (9), and
cross-species face and voice matching (10). Thus, it appears that
specific experience is necessary for maintaining sensitivity to some
initial perceptual discriminations. To determine whether regular
exposure to both French and English confers an advantage in visual
language discrimination, we compared bilingual French-English infants (n
= 24) to their monolingual English counterparts. At an infant age of 6
months, a two-by-two repeated-measures ANOVA analyzing language group
(monolingual versus bilingual) and trial (habituation versus test)
yielded a significant effect for trial [F(1, 22) = 6.65, P < 0.02] with
no interaction. A similar analysis at the age of 8 months yielded only a
significant trial-by-condition interaction [F(1, 22) = 6.92, P < 0.02].
Simple main effects analyses of this interaction showed that, at 8
months, only the bilingual infants looked significantly longer at the
change in language [F(1, 11) = 7.1, P < 0.05 (Fig. 1B)].
Traditionally, visual speech has been regarded as a redundant signal in
verbal communication. The present research shows that visual speech
information alone is sufficient for language discrimination in infancy.
Moreover, this finding indicates that visual speech may also play a more
critical role than previously anticipated in helping infants narrow
their perceptual sensitivities to match the distinctions necessary in
their language learning environment. Notably, bilingual infants
advantageously maintain the discrimination abilities needed for
separating and learning multiple languages.
References
* 1. W. H. Sumby, I. Pollack, J. Acoust. Soc. Am. 26, 212 (1954).
[Medline]
* 2. B. Dodd, D. K. Burnham, Volta Rev. 90, 45 (1988).
* 3. S. Soto-Faraco et al., Percept. Psychophys. 69, 218 (2007).
* 4. J. Mehler et al., Cognition 29, 143 (1988). [CrossRef] [ISI]
[Medline]
* 5. L. Bosch, N. Sebastián-Gallés, Cognition 65, 33 (1997).
[CrossRef] [ISI] [Medline]
* 6. J. F. Werker, R. C. Tees, Infant Behav. Dev. 7, 49 (1984). [ISI]
* 7. P. K. Kuhl et al., Dev. Sci. 9, F13 (2006). [CrossRef] [ISI]
[Medline]
* 8. E. E. Hannon, S. E. Trehub, Proc. Natl. Acad. Sci. U.S.A. 102,
12639 (2005).[Abstract/Free Full Text]
* 9. O. Pascalis et al., Proc. Natl. Acad. Sci. U.S.A. 102, 5297
(2005).[Abstract/Free Full Text]
* 10. D. J. Lewkowicz, A. A. Ghazanfar, Proc. Natl. Acad. Sci.
U.S.A. 103, 6771 (2006).[Abstract/Free Full Text]
* 11. Materials and methods are available on Science Online.
* 12. Supported by grant funding through Social Sciences and
Humanities Research Council of Canada (SSHRC) and Natural Sciences and
Engineering Research Council of Canada (NSERC) to J.F.W., Human Frontier
Science Program and James S. McDonnell Foundation to J.F.W. and N.S.-G.,
and Human Early Learning Partnership to S.S.-F. and by fellowships from
Killiam Trusts to S.S.-F. and A.V., NSERC to A.V. and W.M.W., and
Michael Smith Foundation for Health Research and SSHRC to W.M.W.
Supporting Online Material
www.sciencemag.org/cgi/content/full/316/5828/1159/DC1
Materials and Methods
Movies S1 and S2
Received for publication 16 November 2006. Accepted for publication 12
February 2007.
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Forwarded for scholarly purposes by
Robert Paul
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