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Phonetics/psychological theories: Liberman, Harris, Hoffman, and Griffith (1957)(1) summarized a decade of research at Haskins Laboratories that revealed a special property of the human adult auditory system. In contrast to every other type of auditory stimulus, whose perception conformed to invariant principles such as Weber’s Law.
Def Weber’s Law: differences in intensity and frequency are discriminated in proportional steps, not absolute steps.
LibermanVsWeber’s Law: Liberman et al. provided compelling evidence that certain classes of speech sounds (notably stop consonants) are not perceived in this monotonic manner.
Rather, speech is perceived in a non-monotonic manner, with discontinuities in discrimination that fall approximately at the edges of perceptual categories. Subsequent work from Haskins (Liberman, Harris, Kinney, & Lane, 1961(2); Liberman, Cooper, Shankweiler, & Studdert Kennedy, 1967)(3) provided even more definitive evidence for what became known as categorical perception (CP).
Categorical Perception (CP): This special mode of perception was characterized by two crucial properties:
(a) tokens presented from a physical continuum were identified (labeled) as a member of one category or the other, with a sharp transition in identification (ID) at the category boundary, and
(b) failure of within-category discrimination and a peak in between-category discrimination for tokens that straddled the category boundary. >Language development/psychological theories.
Language development: Because no speech production was required to document the presence of CP, one could avoid the circular logic of claiming that competence was limited by production deficiencies. Thus, if one could develop a method to test infants on a speech perception task, and if their performance conformed to the CP pattern of discrimination and identification observed in adults, then the presence of a functioning speech mode (i.e., an innate and linguistically relevant perceptual system) would be demonstrated.
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Development: There is no question that infants are better at some phonetic discrimination than adults. For example, infants from a Japanese speaking environment can discriminate the /ri-/li contrast (Tsushima et al., 1994)(4), even though it is not used phonemically by adult speakers of Japanese, and these adult speakers have great difficulty improving their /r/-/l/ discrimination even after extensive training (Lively, Pisoni, Yamada, Tohkura & Yamada, 1994)(5). This suggests that listening experience must play a substantial role in at least some phonetic category discrimination.
Werker and Tees (1984) were the first to show the time-course of such a tuning by the listening environment. Infants from an English speaking environment were able at six months of age to discriminate two non-native phonetic contrasts (from Hindi and from Salish, a Native American language), thereby surpassing their adult English speaking parents. But by 12 months of age the discriminative abilities of infants from an English speaking environment for these two non-native contrasts had fallen to near chance.
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Consonant discrimination: (…) experience with the native language can exert a substantial role in consonant discrimination over the second six months of postnatal life. (…) Kuhl, Williams, Lacerda, Stevens, and Lindblom (1992)(6) showed that the effect of native language experience operates even earlier over vowel contrasts, with language-specific tuning by six months of age. Recent evidence from Kuhl, Tsao, and Liu (2003)(7) suggests that social interaction, rather than mere passive listening, plays a key role in this process of attuning the phonetic categories, and further work from Tsao, Liu, and Kuhl(2004)(8) suggests that early attunement is predictive of later levels of vocabulary size.
1. Liberman, A. M., Harris, K. S., Hoffman, H. S., & Griffith, B.C. (1957). The discrimination of speech sounds within and across phoneme boundaries. Journal of Experimental Psychology, 54, 358—368.
2. Liberman, A. M., Harris, K. S., Kinney, J., & Lane, H. (1961). The discrimination of relative onset-time of the components of certain speech and non-speech patterns. Journal of Experimental Psychology, 61,379—388.
3. Liberman, A. M., Cooper, F. S., Shankweiler, D. P., & Studdert-Kennedy, M. (1967). Perception of the speech code. Psychological Review, 74, 431—461.
4. Tsushima, T. Takizawa, O., Sasaki, M., Siraki, S., Nishi, K., Kohno, M., Menyuk, P., & Best, C. (1994,
October). Discrimination of English/r-l/ and/w-y/ by Japanese infants at 6—12 months: Language specific developmental changes in speech perception abilities. Paper presented at the International Conference on Spoken Language Processing, Yokohama, Japan.
5. Lively, S. E., Pisoni, D. B., Yamada, R. A., Tohkura, Y., & Yamada, T. (1994). Training Japanese listeners to identify English/r/ and /1/. III. Long-term retention of new phonetic categones. Journal of the
Acoustical Society of America, 96, 2076—2087.
6. Kuhl, P. K., Williams, K. A., Lacerda, F., Stevens, K. N., & Lindbiom, B. (1992). Linguistic experience alters phonetic perception in infants by 6 months of age. Science, 255, 606—608.
7. Kuhi, P. K., Tsao. F.-M., & Liu, H.-M. (2003). Foreign-language experience in infancy Effects of short-term exposure and social interaction on phonetic learning. Proceedings of the National Academy of
Sciences, 100, 9096—9101.
8. Tsao, F.-M., Liu, H.-M., & Kuhl, P. K. (2004). Speech perception in infancy predicts language development in the second year of life: A longitudinal study. Child Development, 75, 1067—1084.
Richard N. Aslin, “Language Development. Revisiting Eimas et al.‘s /ba/ and /pa/ Study”, in: Alan M. Slater and Paul C. Quinn (eds.) 2012. Developmental Psychology. Revisiting the Classic Studies. London: Sage Publications_____________Explanation of symbols: Roman numerals indicate the source, arabic numerals indicate the page number. The corresponding books are indicated on the right hand side. ((s)…): Comment by the sender of the contribution. The note [Author1]Vs[Author2] or [Author]Vs[term] is an addition from the Dictionary of Arguments. If a German edition is specified, the page numbers refer to this edition.
Alan M. Slater
Paul C. Quinn
Developmental Psychology. Revisiting the Classic Studies London 2012