Y9062
Barbara T. Conboy1,2, Donna Jackson-Maldonado3, & Patricia K. Kuhl2
Institute for Learning and Brain Sciences
University of Washington, WA, USA
Speech perception in monolingual infants
Dramatic changes in speech perception occur during the first year:
•
By 10-12 months of age, monolingual infants typically discriminate
native consonant contrasts to a greater degree than nonnative
contrasts; at younger ages they discriminate native and nonnative
contrasts more equally. 1 - 11
•
By 11 months, infants from monolingual English-speaking homes show
better discrimination of a native (English) versus nonnative (Spanish)
voice onset time (VOT) contrast when both contrasts are tested
simultaneously, and the degree to which perception favors the native
over nonnative language is positively associated with vocabulary
development. 8 - 10
Research Questions
Results
1. Do 11-month-old infants from bilingual homes discriminate both English [(ta]-[tha])
and Spanish [da]-[ta]) stop consonant contrasts, or only one contrast?
English contrast
Spanish contrast
1.20
2. If there is differential perception of contrasts in bilingual infants, is this linked to
relative experience with each language?
mean d'
Background
Facultad de Lenguas y Letras
Universidad de Querétaro, QRO, MEX
3. Does the discrimination performance of bilingual infants for each contrast resemble
those of infants from monolingual English- and Spanish-speaking homes?
1.00
1.00
0.80
0.80
0.60
0.40
Participants:
18 infants from bilingual English- and Spanish-speaking homes
0.00
0.00
Bil (n=18)
•
•
•
For stop consonants, bilingual infants show native-like perception of
contrasts from both languages by 10 - 12 months 12, 13
For vowels, there is evidence for temporary perceptual reorganization
between 8 and 12 months in which two different vowels from one
language are perceived as a single vowel. 14, 15 These results have been
interpreted to reflect distributional/frequency properties of sounds across
languages and other input factors. 12 - 16
Language dominance has not been systematically measured in most
studies of bilingual infants’ speech perception. Recent
electrophysiological evidence suggests that perceptual patterns are
aligned with language dominance in bilingual infants. 17
The above-referenced results and current models of speech perception
development2,4,7,16 lead to the following predictions:
1. Speech sound discrimination skills in bilingual infants will vary
according to language dominance patterns and other measures of
language development that vary with experience (e.g., vocabulary
size).
2. Perceptual skills in bilingual infants are expected to differ from those of
monolingual infants for each language due to bilingual input factors.
References:
1 Werker,
J., & Tees, R. (1984a). Infant Behavior and Development, 7, 49-63.
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.
4 Best, C. T. & McRoberts, G. W. (2003). Language & Speech, 46, 183-216.
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.
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,
979-1000.
8 Conboy, B.T., Sommerville, J.A., & Kuhl, P.K. (2008). Developmental Psychology, 44(5), 1505 -1512.
9 Rivera-Gaxiola, M., Silva-Pereyra, J., & Kuhl, P.K. (2005a). Developmental Science, 8, 162-172.
10 Rivera-Gaxiola, M., Klarman, L., Garcia-Sierra, A., & Kuhl, P. K. (2005b). NeuroReport, 16, 495-498.
11 Rivera-Gaxiola, M., Silva-Pereyra, J., Klarman, L., Garcia-Sierra, A., Lara-Ayala, L., Cadena-Salazar, C. & Kuhl, P. K. (2007). Developmental
Neuropsychology, 31(3), 363-378.
12 Burns, T. C., Yoshida, K. A., Hill, K., & Werker, J. F. (2007). Applied Psycholinguistics, 28, 455‐474.
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.
16 Maye, J., Weiss, D. J., & Aslin, R. N. (2008). Developmental Science, 11(1), 122‐134.
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
Learning Centers Conference, Seattle, WA..
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
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:
User’s guide and technical manual. Baltimore, MD: Paul H. Brookes Publishing Company.
2 Werker,
All infants were full-term (> 37 weeks gestation), had experienced no more than 2 ear
infections, and passed criterion-testing* for inclusion in the study.
Study Design:
11-month-old infants from bilingual homes behaviorally discriminated stop consonant
voicing contrasts from both their languages, consistent with previous research 12.
•
Perceptual patterns were linked to relative experience with each language: Spanishdominant infants showed better sensitivity to the Spanish contrast than Englishdominant infants. This finding is consistent with models of speech perception that
emphasize continuity between perception and other aspects of language development
2,7 . Distributional accounts 3, 7, 12 - 16 would predict that reduced discrimination of the
Spanish contrast in English-dominant infants is influenced by the distribution of [d] and
[t] in the input - further research on the input to bilingual infants is needed.
•
The discrimination skills of bilingual infants did not exactly resemble those of
monolingual infants. Although it did not reach statistical significance in this sample, there
was a graded pattern of discrimination for the Spanish contrast (Spanish-monolingual >
Bilingual > English-monolingual infants). However, discrimination of the Spanish
contrast in the Spanish-dominant bilingual infants exceeded that of Spanish-monolingual
infants. One possible explanation for this unexpected finding (consistent with previous
research8) is that enhanced ability to control attention in bilingual development allowed
the bilingual infants to switch perceptually between language-relevant acoustic cues in
the experimental task used here. This hypothesis requires further research with larger
samples. Data on attentional control skills in the bilingual and monolingual infants are
currently being analyzed.
•
Spanish-monolingual infants discriminated the nonnative English contrast at an age
when nonnative sensitivity is not typically observed 11. This result may be due in part to
the acoustic saliency of the aspirated-unaspirated English voicing contrast, but is also
consistent with the Perceptual Assimilation Model,4 which proposes that declines in
nonnative-contrast perception are influenced by how the infant assimilates contrasting
sounds into native phoneme categories. Aspirated [th] does not occur in Spanish;
although it might be assimilated into the /t/ category for native Spanish learners, it would
be considered a poor exemplar of /t/ and could remain discriminable from good tokens
of Spanish /t/ (i.e., [t]).
• Parents completed the MacArthur-Bates Communicative Development Inventory-Words
& Gestures (CDI) in English14, Spanish14, within one week of Head Turn testing.18 - 19
Double Target Conditioned Head Turn Task
Stimuli
Standard
[da]
[ta]
[tha]
Voice Onset
Time
ms
(VOT)
46
0 12
-24
English
Target
Nonnative target [da]
(Spanish /da/)
VOT = -24 ms
Native target [tha]
(English /ta/)
VOT = +46 ms
Standard [ta]
(Spanish /ta/,English /da/)
VOT = +12 ms
5
4
3
2
1
0
Release of
stop consonant
0
0.2297
0
0.2292
0
0.2300
Time (seconds)
Duration = 229.65 ms
Interstimulus interval = 2000 ms
Intensity level = 65 dbA
From: Rivera-Gaxiola, M., Silva-Pereyra, J., & Kuhl, P.K. (2005a).
Developmental Science, 8, 162-172.
Procedure
Conditioning Phase (Day 1)
Intensity
Cue
2 consecutive
correct
No
Intensity
Cue
Testing Phase (Day 2)
3 consecutive
correct
d’ = z(hit rate) - z(false alarm rate)
When bilingual infants were grouped based on
language dominance (CDI “Words Understood”
score), there was a contrast x group interaction,
F(1,16) = 5.394 p < .05, p2 = .27. Planned comparisons
showed better discrimination of the Spanish
contrast in English- than in Spanish-dominant
infants,
t(17) = 2.33, p < .05, 2-tailed, 95% CID = .04, .95,
•
• All infants completed the Double-Target Conditioned Head-Turn task 8 over two
consecutive days
Spanish
Target
Spanish dominant
Summary and Discussion
17 infants from monolingual English-speaking homes
Frequency (kHz)
Results are mixed with regard to perceptual patterns in bilingual infants:
English dominant
d = 1.19.
15 infants from monolingual Spanish-speaking homes
Speech perception in bilingual infants
0.40
0.20
Sp-mono (n=15)
Error bars = +/- 1 SE
0.60
0.20
Eng-mono (n=17)
Spanish contrast
1.20
Error bars = +/- 1 SE
Overall, infants showed better discrimination for the
English (d’ = .78) vs. the Spanish (d’ = .49) contrast,
F(1,47) = 8.33, p < .01, 95% CID = .09, .48, d = .53. Planned
comparisons showed that this differential discrimination
was only significant in the English-monolingual infants
t(16) = 2.58, p < .05, 2-tailed, 95% CID = .08, .81, d = 73.
Method
English contrast
mean d'
Department of Communicative Disorders
University of Redlands, CA, USA
TRIALS
RESULTS
50% Change
50% Control
Hit
False
Alarm
Miss Correct
Reject
Listening
to
standard
Turning
head to
target
d’ difference = d’ (native) - d’ (nonnative)
* To be included in the final data set, infants had to reach the following criteria: false alarm rate < .80 and at
least one positive d’ score for either contrast.
Acknowledgements:
This authors thank:
Maritza-Rivera Gaxiola for providing the speech stimuli; Denise Padden, Lindsay Klarman, Robin Cabiness, Caryn Deskines, Josie Randles, Marta Dorantes, Ana
Luisa Martínez, & Marcia Hernández for assistance with data collection; and the infants and their families who generously donated their time to this study.
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.
Contact: barbara_conboy@redlands.edu