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ASHA 2009

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ASHA 2009 Powered By Docstoc
					                                                                                                                                                                                                                                                                Y9062




                                                                                                                                                              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




                                                                                                                                                                                                                                                                                                                                                                                                                                            mean d'
                                                                                                                                                                                                                                                                                                                                                       mean d'
                                                                                                                                                                                                                                                                                                                                                                 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
                                                                                                                                                                                                                                      Frequency (kHz)
                                                                                                                                                                                                                                                        5

        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
                                                                                                                                                                                                                    (VOT)                               1
                                                                                                                                                                                                                                                                                                                                                       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;
                                                                                                                                                                                                                                                                                                                              standard
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
        979-1000.                                                                                                                                                                                                                                                RESULTS
8 Conboy, B.T., Sommerville, J.A., & Kuhl, P.K. (2008). Developmental Psychology, 44(5), 1505 -1512.
                                                                                                                                                                                                  No
                                                                                                                                                                                                                             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.
                                                                                                                                                                     Cue       correct
                                                                                                                                                                                               Intensity
                                                                                                                                                                                                             correct
                                                                                                                                                                                                                             50% Change
                                                                                                                                                                                                                                                                      Alarm                                                   Turning
                                                                                                                                                                                                                                                                                                                                                       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: barbara_conboy@redlands.edu