Barbara T. Conboy1,2, Donna Jackson-Maldonado3, & Patricia K. Kuhl2
Department of Communicative Disorders Institute for Learning and Brain Sciences Facultad de Lenguas y Letras
University of Redlands, CA, USA University of Washington, WA, USA Universidad de Querétaro, QRO, MEX
Background Research Questions Results
Speech perception in monolingual infants 1. Do 11-month-old infants from bilingual homes discriminate both English [(ta]-[tha]) English contrast Spanish contrast English contrast Spanish contrast
Dramatic changes in speech perception occur during the first year: and Spanish [da]-[ta]) stop consonant contrasts, or only one contrast? 1 .2 0 Error bars = +/- 1 SE 1.20
Error bars = +/- 1 SE
1 .0 0 1.00
• By 10-12 months of age, monolingual infants typically discriminate 2. If there is differential perception of contrasts in bilingual infants, is this linked to 0 .8 0 0.80
0 .6 0 0.60
native consonant contrasts to a greater degree than nonnative relative experience with each language? 0 .4 0 0.40
contrasts; at younger ages they discriminate native and nonnative 0 .2 0 0.20
3. Does the discrimination performance of bilingual infants for each contrast resemble
contrasts more equally. 1 - 11 0 .0 0 0.00
those of infants from monolingual English- and Spanish-speaking homes? Eng-mono (n=17) Sp-mono (n=15) Bil (n=18) English dominant Spanish dominant
• By 11 months, infants from monolingual English-speaking homes show Overall, infants showed better discrimination for the When bilingual infants were grouped based on
better discrimination of a native (English) versus nonnative (Spanish) Method English (d’ = .78) vs. the Spanish (d’ = .49) contrast, language dominance (CDI “Words Understood”
voice onset time (VOT) contrast when both contrasts are tested F(1,47) = 8.33, p < .01, 95% CID = .09, .48, d = .53. Planned score), there was a contrast x group interaction,
comparisons showed that this differential discrimination F(1,16) = 5.394 p < .05, p2 = .27. Planned comparisons
simultaneously, and the degree to which perception favors the native Participants: was only significant in the English-monolingual infants showed better discrimination of the Spanish
over nonnative language is positively associated with vocabulary t(16) = 2.58, p < .05, 2-tailed, 95% CID = .08, .81, d = 73. contrast in English- than in Spanish-dominant
18 infants from bilingual English- and Spanish-speaking homes infants,
development. 8 - 10 t(17) = 2.33, p < .05, 2-tailed, 95% CID = .04, .95,
d = 1.19.
15 infants from monolingual Spanish-speaking homes
Speech perception in bilingual infants Summary and Discussion
17 infants from monolingual English-speaking homes
Results are mixed with regard to perceptual patterns in bilingual infants:
All infants were full-term (> 37 weeks gestation), had experienced no more than 2 ear • 11-month-old infants from bilingual homes behaviorally discriminated stop consonant
• For stop consonants, bilingual infants show native-like perception of infections, and passed criterion-testing* for inclusion in the study. voicing contrasts from both their languages, consistent with previous research 12.
contrasts from both languages by 10 - 12 months 12, 13
• Perceptual patterns were linked to relative experience with each language: Spanish-
• For vowels, there is evidence for temporary perceptual reorganization Study Design:
dominant infants showed better sensitivity to the Spanish contrast than English-
between 8 and 12 months in which two different vowels from one • All infants completed the Double-Target Conditioned Head-Turn task 8 over two dominant infants. This finding is consistent with models of speech perception that
language are perceived as a single vowel. 14, 15 These results have been consecutive days emphasize continuity between perception and other aspects of language development
interpreted to reflect distributional/frequency properties of sounds across 2,7 . Distributional accounts 3, 7, 12 - 16 would predict that reduced discrimination of the
languages and other input factors. 12 - 16 • Parents completed the MacArthur-Bates Communicative Development Inventory-Words Spanish contrast in English-dominant infants is influenced by the distribution of [d] and
& Gestures (CDI) in English14, Spanish14, within one week of Head Turn testing.18 - 19 [t] in the input - further research on the input to bilingual infants is needed.
• Language dominance has not been systematically measured in most
studies of bilingual infants’ speech perception. Recent
Double Target Conditioned Head Turn Task • The discrimination skills of bilingual infants did not exactly resemble those of
electrophysiological evidence suggests that perceptual patterns are
monolingual infants. Although it did not reach statistical significance in this sample, there
aligned with language dominance in bilingual infants. 17 was a graded pattern of discrimination for the Spanish contrast (Spanish-monolingual >
The above-referenced results and current models of speech perception Bilingual > English-monolingual infants). However, discrimination of the Spanish
development2,4,7,16 lead to the following predictions: Stimuli contrast in the Spanish-dominant bilingual infants exceeded that of Spanish-monolingual
infants. One possible explanation for this unexpected finding (consistent with previous
Nonnative target [da] Standard [ta] Native target [tha]
1. Speech sound discrimination skills in bilingual infants will vary Spanish English (Spanish /da/) (Spanish /ta/,English /da/) (English /ta/) research8) is that enhanced ability to control attention in bilingual development allowed
according to language dominance patterns and other measures of Target Standard Target VOT = -24 ms VOT = +12 ms VOT = +46 ms
the bilingual infants to switch perceptually between language-relevant acoustic cues in
language development that vary with experience (e.g., vocabulary [da] [ta] [tha] 4
the experimental task used here. This hypothesis requires further research with larger
Voice Onset 3
size). ms Time 2 samples. Data on attentional control skills in the bilingual and monolingual infants are
-24 0 12 46
currently being analyzed.
2. Perceptual skills in bilingual infants are expected to differ from those of Release of 0
0 0.2297 0 0.2292 0 0.2300
monolingual infants for each language due to bilingual input factors. stop consonant Time (seconds)
Duration = 229.65 ms
• Spanish-monolingual infants discriminated the nonnative English contrast at an age
Interstimulus interval = 2000 ms
From: Rivera-Gaxiola, M., Silva-Pereyra, J., & Kuhl, P.K. (2005a).
Developmental Science, 8, 162-172.
when nonnative sensitivity is not typically observed 11. This result may be due in part to
References: Intensity level = 65 dbA the acoustic saliency of the aspirated-unaspirated English voicing contrast, but is also
1 Werker, J., & Tees, R. (1984a). Infant Behavior and Development, 7, 49-63. consistent with the Perceptual Assimilation Model,4 which proposes that declines in
2 Werker, J. F. & Curtin, S. (2005). Language Learning and Development, 1, 197-234.
3 Anderson, J. L., Morgan, J. L., & White, K. S. (2003). Language and Speech, 46(2-3), 155-182.
Procedure nonnative-contrast perception are influenced by how the infant assimilates contrasting
4 Best, C. T. & McRoberts, G. W. (2003). Language & Speech, 46, 183-216. Listening
5 Kuhl, P.K., Stevens, E., Hayashi, A., Deguchi, T., Kiritani, S., & Iverson, P. (2006). Developmental Science, 9, F13-F21.
6 Kuhl, P.K., Conboy, B.T., Padden, D., Nelson, T. & Pruitt, J. (2005). Language Learning and Development, 1, 237-264. Conditioning Phase (Day 1) Testing Phase (Day 2)
to sounds into native phoneme categories. Aspirated [th] does not occur in Spanish;
7 Kuhl, P.K., Conboy, B.T., Coffey-Corina, S., Padden, D., Rivera-Gaxiola, M., & Nelson, T. (2008). Philosophical Transactions of the Royal Society B, 363,
although it might be assimilated into the /t/ category for native Spanish learners, it would
8 Conboy, B.T., Sommerville, J.A., & Kuhl, P.K. (2008). Developmental Psychology, 44(5), 1505 -1512.
TRIALS be considered a poor exemplar of /t/ and could remain discriminable from good tokens
9 Rivera-Gaxiola, M., Silva-Pereyra, J., & Kuhl, P.K. (2005a). Developmental Science, 8, 162-172.
Intensity 2 consecutive 3 consecutive Hit False
10 Rivera-Gaxiola, M., Klarman, L., Garcia-Sierra, A., & Kuhl, P. K. (2005b). NeuroReport, 16, 495-498.
of Spanish /t/ (i.e., [t]).
11 Rivera-Gaxiola, M., Silva-Pereyra, J., Klarman, L., Garcia-Sierra, A., Lara-Ayala, L., Cadena-Salazar, C. & Kuhl, P. K. (2007). Developmental Cue 50% Control
Neuropsychology, 31(3), 363-378.
Miss Correct head to
12 Burns, T. C., Yoshida, K. A., Hill, K., & Werker, J. F. (2007). Applied Psycholinguistics, 28, 455‐474. Reject target
13 Sundara, M., Polka, L., & Molnar, M. (2008). Cognition, 108, 232‐242.
14 Bosch, L., & Sebastian‐Galles, N. (2003). Language and Speech, 46, 217‐243.
15 Sebastián-Galles, N. & Bosch, L. (2009). Developmental Science, 12(6), 874-887. d’ = z(hit rate) - z(false alarm rate) d’ difference = d’ (native) - d’ (nonnative) Acknowledgements:
16 Maye, J., Weiss, D. J., & Aslin, R. N. (2008). Developmental Science, 11(1), 122‐134. This authors thank:
17 García-Sierra, A., Rivera-Gaxiola, M., Conboy, B., Romo, H., & Kuhl, P.K. (2009, February). Paper presented at the Second Annual Inter-Science of Maritza-Rivera Gaxiola for providing the speech stimuli; Denise Padden, Lindsay Klarman, Robin Cabiness, Caryn Deskines, Josie Randles, Marta Dorantes, Ana
Learning Centers Conference, Seattle, WA.. Luisa Martínez, & Marcia Hernández for assistance with data collection; and the infants and their families who generously donated their time to this study.
18 Fenson, L., Dale, P.S., Reznick, J.S., Thal, D., Bates, E., Hartung, J.P., Pethick, S., & Reilly, J.S. (1993). The MacArthur Communicative Development * To be included in the final data set, infants had to reach the following criteria: false alarm rate < .80 and at
Work supported by NSF Science of Learning Grant (SBE-0354453), NICHD F32 to B. Conboy, and NIH UW Research Core Grant, University of Washington P30 DC04661.
Inventories: User’s Guide and Technical Manual. San Diego, CA: Singular Publishing Group.
19 Jackson-Maldonado, D., Thal, D., Marchman, V., Fenson, L., Newton, T., & Conboy, B. (2003). El Inventario del Desarrollo de Habilidades Comunicativas:
least one positive d’ score for either contrast.
User’s guide and technical manual. Baltimore, MD: Paul H. Brookes Publishing Company. Contact: firstname.lastname@example.org