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To learn or not to learn: The growing paths of children’s phonological neighborhoods

To learn or not to learn: The growing paths of children’s phonological neighborhoods. Yao Yao @berkeley.edu 2009-1-11. Overview. Background Data Study 1 Study 2 Study 3 Discussion. Phonological neighborhood (PN). General idea

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To learn or not to learn: The growing paths of children’s phonological neighborhoods

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  1. To learn or not to learn: The growing paths of children’s phonological neighborhoods Yao Yao @berkeley.edu 2009-1-11 YY @ LSA Annual Meeting 2009

  2. Overview • Background • Data • Study 1 • Study 2 • Study 3 • Discussion YY @ LSA Annual Meeting 2009

  3. Phonological neighborhood (PN) • General idea • The lexicon can be viewed as a network of words, in which similar-sounding words are connected to form phonological neighborhoods. • Defining neighbors • One-phoneme difference rule (Luce & Pisoni, 1998). it kit cape cap cat mop mat map YY @ LSA Annual Meeting 2009

  4. Evidence for PN • Speech perception • Inhibitory effect (Luce & Pisoni, 1998) • Speech production • Facilitative effect (Vitevitch, 2002) • Hyperarticulation (Munson & Solomon, 2004) YY @ LSA Annual Meeting 2009

  5. Children’s PN development • Start small and sparse (Charles-Luce & Luce, 1990; Logan, 1992; Storkel, 2002) • How do children’s phonological neighborhoods grow? • From the target language (TL) perspective • Early acquired words are short in length, high in frequency and from dense neighborhoods in TL (Storkel, 2004) • From the local child language (CL) perspective • Acquire similar-sounding words? • Acquire dissimilar-sounding words? YY @ LSA Annual Meeting 2009

  6. Puzzle • Perceptual abilities • Infants at a very young age can perceive fine phonetic detail (Aslin, Jusczyk & Pisoni, 1998) • Used in word learning ? • Children have difficulty in learning similar-sounding novel words (Stager & Werker, 1997) • Children are sensitive to the phonetic detail in the input. (Zamuner, 2006, 2009; Coady & Aslin, 2003) YY @ LSA Annual Meeting 2009

  7. Two models • LRM (Lexical Restructuring Model; Metsala & Walley, 1998) • Holistic lexical representations initially. More detailed phonemic representation is necessitated as the vocabulary grows. • PRIMIR (Processing Rich Information from Multidimensional Interaction Representations; Werker & Curtin, 2005) • “phonetic detail is incorporated into early lexical representations” (Zamuner, 2009:7) YY @ LSA Annual Meeting 2009

  8. Examining PN development • If holistic representation… • Acquire dissimilar-sounding words • Avoid dense neighborhoods • If detailed phonetic representation… • Acquire similar-sounding words • Form dense neighborhoods • Influence from the TL YY @ LSA Annual Meeting 2009

  9. Database • From the Manchester corpus in CHILDES database (Theakston, et al., 2001; MacWhinney, 1991) • Two monolingual British children • Joel [1;11- 2;10] “word learner“ (Ke & Yao, 2008) • Ruth [2;0 - 2;11] “grammar learner“ (Ke & Yao, 2008) • 1-year longitudinal study • 34 recordings, 1hr each, approx. 1 per 10 days YY @ LSA Annual Meeting 2009

  10. Stage division (Ke & Yao, 2008) • 0.5 increase in MLU (Mean Length of Utterance) per stage • 5 recording sessions • 40 days • Non-overlapping • Joel • S1, S2, S3, S4a, S4b, S5 • Ruth • S1, S2, S3a, S3b, S4, S5 YY @ LSA Annual Meeting 2009

  11. Network model • Input • Spontaneous speech of the child • Phonetic transcription is obtained from the CELEX database. • No regular inflected forms or contracted forms if the base forms already exist • Neighborhood definition • One-phoneme difference rule YY @ LSA Annual Meeting 2009

  12. Preliminary counts YY @ LSA Annual Meeting 2009

  13. Study 1: size and average density of 3-phoneme words in children’s networks • Average density • Size YY @ LSA Annual Meeting 2009

  14. Study 1: size and average density of 3-phoneme words in children’s networks • Two children’s data overlayed (with Joel’s shifted by 2 stages) Joel is probably more advanced than Ruth by 2 stages. YY @ LSA Annual Meeting 2009

  15. Study 1: size and average density of 3-phoneme words in the local network • Q: is the increase in density an artifact of the increase in lexicon size? • Coady & Aslin (2003) • Calculate neighborhood density as a proportion of the entire lexicon, not in raw counts of neighbors. YY @ LSA Annual Meeting 2009

  16. Study 1: size and average density of 3-phoneme words in the local network • Neighborhood density relative to vocabulary size YY @ LSA Annual Meeting 2009

  17. Study 1: Discussion • Absolute number of neighbors increase over time • When lexicon size is normalized, neighborhood density • Increases in Ruth’s early stages • Slightly decreases in Ruth’s late stages and all Joel’s stages YY @ LSA Annual Meeting 2009

  18. Study 2: neighborhood density of the same 3-phoneme words in TL • Neighborhood densities in CL and TL are partially correlated (corr <0.4) YY @ LSA Annual Meeting 2009

  19. Study 2: Discussion • Average neighborhood density (in adult lexicon) • Increases in Ruth’s early stages • decreases in Ruth’s late stages and all Joel’s stages • Joel’s development is probably two stages more advanced than Ruth YY @ LSA Annual Meeting 2009

  20. Study 3 • Assumptions • Word learning as a dynamic process • Acquire words • Lose words • Stage networks represent the lexicon of the child at that stage • Q: What words are acquired, lost, and kept? Hi-density words or low-density words? YY @ LSA Annual Meeting 2009

  21. Study 3: What words are acquired, lost and kept? • New vs. old words • New words: words that don’t exist in the previous lexicon • Old words: words that already exist in the previous lexicon • Lost vs. retained words • Lost words: words that don’t exist in the next lexicon • Retained words: words that still exist in the next lexicon S1 lexicon S2 lexicon Lost Old/ Retained New YY @ LSA Annual Meeting 2009

  22. Study 3: What words are acquired, lost and kept? • Average local density of 3-phoneme new vs. old words YY @ LSA Annual Meeting 2009

  23. Study 3: What words are acquired, lost and kept? • Average local density of 3-phoneme lost vs. retained words YY @ LSA Annual Meeting 2009

  24. Study 3: What words are acquired, lost and kept? • After • Avg. density = (4+6)*2/7=2.85 • Before • Avg. density = 2 YY @ LSA Annual Meeting 2009

  25. Study 3: What words are acquired, lost and kept? • Average density of 3-phoneme lost, new and old/retained words in the target language YY @ LSA Annual Meeting 2009

  26. Study 3: Discussion • In Ruth’s early stages • Newly-acquired words are structurally MORE important than existing words • Structurally-important words are MORE susceptible to being lost • In Ruth’s late stages and all Joel’s stages • Newly-acquired words are structurally LESS important than existing words • Structurally-important words are LESS susceptible to being lost YY @ LSA Annual Meeting 2009

  27. General Discussion • In early stages of lexical acquisition • acquire words that sound similar to existing ones and increase local density • build up the backbone of the phonological network by adding important nodes • important words are also easier to lose • After that • words that are acquired are less important • important words are less likely to be lost YY @ LSA Annual Meeting 2009

  28. Implications • Pressure to form/deform denser neighborhoods coexist in early stages • Perceptual abilities • Probably used from the early stage of word learning PRIMIR model • Stabilize after a while YY @ LSA Annual Meeting 2009

  29. Implications • Critical mass hypothesis • after the lexicon exceeds a critical size, qualitative changes in linguistic performance and/or acquisition strategy will take place (Marchman & Bates, 1994) • Critical size • ~200 words • cf. Vogel Sosa & Stoel-Gammon (2006) YY @ LSA Annual Meeting 2009

  30. Complications • Token frequency • Neighborhood density in CL is partially correlated with token frequency in child speech (cor < 0.45) and maternal input (cor <0.45) . YY @ LSA Annual Meeting 2009

  31. Caveats • Sampling frequency • 5hrs recording spread over ~40 days • Is the stage lexicon a decent representation of the child’s productive lexicon? • Is the division of new/old, lost/retained words fair enough? • Phonological network model • The use of dictionary pronunciation of words • Definition of neighbors • Different types of neighbors YY @ LSA Annual Meeting 2009

  32. Acknowledgement Child subjects The Manchester Corpus CHILDES database Prof. Susanne Gahl Prof. Keith Johnson Audience at the Berkeley Phonology Phorum YY @ LSA Annual Meeting 2009

  33. Selected references • Aslin, R.N., Jusczyk, P.W. & Pisoni, D.B. (1998). Speech and auditory processing during infancy: constraints on and precursors to language. In D. Kuhn & R. Siegler (eds), Handbook of child psychology: cognition, perception and language, vol. 2, NY: Wiley. • Charles-Luce, J. & Luce, P.A. (1990). Similarity neighborhoods of words in young children’s lexicons. Journal of Child Language 17, 205-215. • Coady, J.A. & Aslin, R.N. (2003). Phonological neighborhoods in the developing lexicon. Journal of Child Language 30, 441-469. • Logan, J.S. (1992). A computational analysis of young children’s lexicons (Tech. Rep. No. 8). Bloomington, IN: Speech Research Laboratory, Dept. of Psychology, Indiana Univ. • Luce, P.A. & Pisoni, D.B. (1998). Recognizing spoken words: the neighborhood density activation model. Ear and Hearing 19, 1-36. • MacWhinney, B. (1991). The Childes Project: Tools for Analyzing Talk. Lawrence Erlbaum Associates . • Marchman, V.A. & Bates, E. (1994) Continuity in lexical and morphological development: a test of the critical-mass hypothesis. Journal of Child Language 21, 339-366. • Metsala, J. L. & Walley, A. C. (1998). Spoken vocabulary growth and the segmental restructuring of lexical representations : Precursors to phonemic awareness and early reading ability. In J. L. Metsala & L. C. Ehri (eds), Word recognition in beginning literacy, 89–120. New York: Erlbaum. YY @ LSA Annual Meeting 2009

  34. Selected references • Munson, B. & Solomon, N.P. (2004) . The effect of phonological neighborhood density on vowel articulation . Journal of Speech, Language, and Hearing Research 47(5), 1048-1058 • Stager, C.L. & Werker, J.F. (1997). Infants listen for more phonetic detail in speech perception than in word-learning tasks. Nature 388, 381-382. • Storkel, H.L. (2002). Restructuring of similarity neighbourhoods in the developing mental lexicon. Journal of Child Language 29, 251-274. • Storkel, H.L. (2004). Do children acquire dense neighborhoods? An investigation of similarity neighborhoods in lexicla acquisition. Applied Psycholinguistics 25, 201-221. • Theakston, A. L., Lieven, E. V. M., Pine, J. M., & Rowland, C. F. (2001). The role of performance limitations in the acquisition of verb-argument structure: an alternative account. Journal of Child Language 28, 127-152. • Vitevitch, . (2002). The influence of phonological similarity neighborhoods on speech production. Journal of Experimental Psychology: Learning, Memory, and Cognition 28(4), 735–747. • Vogel Sosa, A. & Stoel-Gammon, C. (2006). Patterns of intra-word phonological variability during the second year of life. Journal of Child Language 33, 31–50. • Werker, J. F. & Curtin, S. (2005). PRIMIR: A developmental framework of infant speech processing. Language Learning and Development 1, 197–234. • Zamuner, T. S. (2006). Sensitivity to word-final phonotactics in 9- to 16-month-old infants. Infancy 10, 77–95. YY @ LSA Annual Meeting 2009

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