[lit-ideas] Re: Amazing babies

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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