1. Ladefoged, P. Vowels and Consonants: An Introduction to the Sounds of Language 2nd edn (Blackwell, Oxford, UK, 2004).

2. Liberman, A. M., Cooper, F. S., Shankweiler, D. P. & Studdert-Kennedy, M. Perception of the speech code. Psychol. Rev. 74, 431-461 (1967).

3. Eimas, P. D., Siqueland, E. R., Jusczyk, P. & Vigorito, J. Speech perception in infants. Science 171, 303-306 (1971).

4. Lasky, R. E., Syrdal-Lasky, A. & Klein, R. E. VOT discrimination by four to six and a half month old infants from Spanish environments. J. Exp. Child Psychol. 20, 215-225 (1975).

5. Eimas, P. D. Auditory and phonetic coding of the cues for speech: discrimination of the /r-l/ distinction by young infants. Percept. Psychophys. 18, 341-347 (1975).

6. Werker, J. F. & Lalonde, C. Cross-language speech perception: initial capabilites and developmental change. Dev. Psychol. 24, 672-683 (1988).

7. Miyawaki, K. et al. An effect of linguistic experience: the discrimination of /r/ and /l/ by native speakers of Japanese and English. Percept. Psychophys. 18, 331-340 (1975).

8. Stevens, K. N. Acoustic Phonetics (MIT Press, Cambridge, Massachusetts, 2000).

9. Kuhl, P. K. & Miller, J. D. Speech perception by the chinchilla: voice-voiceless distinction in alveolar plosive consonants. Science 90, 69-72 (1975).

10. Kuhl, P. K. & Miller, J. D. Speech perception by the chinchilla: identification functions for synthetic VOT stimuli. J. Acoust. Soc. Am. 63, 905-917 (1978).

11. Kuhl, P. K. & Padden, D. M. Enhanced discriminability at the phonetic boundaries for the place feature in macaques. J. Acoust. Soc. Am. 73, 1003-1010 (1983).

12. Pisoni, D. B. Identification and discrimination of the relative onset time of two component tones: implications for voicing perception in stops. J. Acoust. Soc. Am. 61, 1352-1361 (1977).

13. Jusczyk, A. M., Pisoni, D. B., Walley, A. & Murray, J. Discrimination of relative onset time of two-component tones by infants. J. Acoust. Soc. Am. 67, 262-270 (1980).

14. Kuhl, P. K. Theoretical contributions of tests on animals to the special-mechanisms debate in speech. Exp. Biol. 45, 233-265 (1986).

15. Kuhl, P. K. in Plasticity of Development (eds Brauth, S. E., Hall, W. S. & Dooling, R. J.) 73-106 (MIT Press, Cambridge, Massachusetts, 1991).

16. Aslin, R. N. & Pisoni, D. B. in Child Phonology: Perception and Production (eds Yeni-Komshian, G., Kavanagh, J. & Ferguson, C.) 67-96 (Academic, New York, 1980).

17. Burnham, D. Developmental loss of speech perception: exposure to and experience with a first language. Appl. Psycholinguist. 7, 207-240 (1986).

18. Kuhl, P. K. in Neonate Cognition: Beyond the Blooming Buzzing Confusion (eds Mehler, J. & Fox, R.) 231-262 (Lawrence Erlbaum Associates, Hillsdale, New Jersey, 1985).

19. Hillenbrand, J. Speech perception by infants: categorization based on nasal consonant place of articulation. J. Acoust. Soc. Am. 75, 1613-1622 (1984).

20. Kuhl, P. K. Speech perception in early infancy: perceptual constancy for spectrally dissimilar vowel categories. J. Acoust. Soc. Am. 66, 1668-1679 (1979).

21. Kuhl, P. K. Perception of auditory equivalence classes for speech in early infancy. Infant Behav. Dev. 6, 263-285 (1983).

22. Miller, J. L. & Liberman, A. M. Some effects of later-occurring information on the perception of stop consonant and semivowel. Percept. Psychophys. 25, 457-465 (1979).

23. Eimas, P. D. & Miller, J. L. Contextual effects in infant speech perception. Science 209, 1140-1141 (1980).

24. Zue, V. & Glass, J. Conversational interfaces: advances and challenges. Proc. IEEE 88, 1166-1180 (2000).

25. Kuhl, P. K. & Meltzoff, A. Infant vocalizations in response to speech: vocal imitation and developmental change. J. Acoust. Soc. Am. 100, 2425-2438 (1996). Vocalizations of infants watching a video of a female talker were recorded at 12, 16 and 20 weeks of age. The results show developmental change between 12 and 20 weeks of age and also provide evidence of vocal imitation in infants by 20 wee......

26. Werker, J. F. & Tees, R. C. Cross-language speech perception: evidence for perceptual reorganization during the first year of life. Infant Behav. Dev. 7, 49-63 (1984).

27. Best, C. & McRoberts, G. W. Infant perception of non-native consonant contrasts that adults assimilate in different ways. Lang. Speech 46, 183-216 (2003).

28. Tsushima, T. et al. Proceedings of the International Conference on Spoken Language Processing Vol. S28F-1, 1695-1698 (Yokohama, Japan, 1994).

29. Kuhl, P. K., Tsao, F. M., Liu, H. M., Zhang, Y. & de Boer, B. in The Convergence of Natural and Human Science (eds Domasio, A. et al.) 136-174 (The New York Academy of Science, New York, 2001).

30. Rivera-Gaxiola, M., Silva-Pereyra, J. & Kuhl, P. K. Brain potentials to nativeand non-native speech contrasts in seven and eleven-month-old American infants. Dev. Sci. (in the press). An ERP study showing that at 11 months, the infant brain remains sensitive to non-native-language contrasts. Infants' responsiveness to native-language consonant contrasts also increased over time.

31. Kuhl, P. K., Tsao, F.-M. & Liu, H.-M. Foreign-language experience in infancy: effects of short-term exposure and social interaction on phonetic learning. Proc. Natl Acad. Sci. USA 100, 9096-9101 (2003). Two studies showing that learning can occur with only short-term exposure to a language in infants, and that it is enhanced by social interaction.

32. Cheour, M. et al. Development of language-specific phoneme representations in the infant brain. Nature Neurosci. 1, 351-353 (1998).

33. Kuhl, P. K., Tsao, F. M., Liu, H. M., Zhang, Y. & De Boer, B. Language/culture/mind/brain. Progress at the margins between disciplines. Ann. NY Acad. Sci. 935, 136-174 (2001).

34. Fant, G. Speech Sounds and Features (MIT Press, Cambridge, Massachusetts, 1973).

35. Hillenbrand, J., Getty, L., Clark, M. & Wheeler, K. Acoustic characteristics of American English vowels. J. Acoust. Soc. Am. 97, 3099-3111 (1995).

36. Perkell, J. & Klatt, D. Invariance and Variability in Speech Processes 1-604 (Lawrence Erlbaum Associates, Hillsdale, New Jersey, 1986).

37. Lacerda, F. The perceptual magnet effect: an emergent consequence of exemplar-based phonetic memory. Proc. Int. Congr. Phonetic Sci. 2, 140-147 (1995).

38. Lisker, L. & Abramson, A. S. A cross-language study of voicing in initial stops: acoustical measurements. Word 20, 384-422 (1964).

39. Kuhl, P. K. Early linguistic experience and phonetic perception: implications for theories of developmental speech perception. J. Phonetics 21, 125-139 (1993).

40. Maye, J., Werker, J. F. & Gerken, L. Infant sensitivity to distributional information can affect phonetic discrimination. Cognition 82, B101-B111 (2002).

41. Kuhl, P. K., Williams, K. A., Lacerda, F., Stevens, K. N. & Lindblom, B. Linguistic experience alters phonetic perception in infants by 6 months of age. Science 255, 606-608 (1992).

42. Kuhl, P. K. Human adults and human infants show a `perceptual magnet effect' for the prototypes of speech categories, monkeys do not. Percept. Psychophys. 50, 93-107 (1991).

43. Rosch, E. Cognitive reference points. Cognit. Psychol. 7, 532-547 (1975).

44. Jusczyk, P., Luce, P. & Charles-Luce, J. Infants' sensitivity to phonotactic patterns in the native language. J. Mem. Lang. 33, 630-645 (1994). This study found that 9-month-old infants, but not 6month-old infants, prefer frequently occurring phonetic patterns in monosyllables.

45. Fenson, L. et al. MacArthur Communicative Development Inventories: User's Guide and Technical Manual (Singular Publishing Group, San Diego, California, 1993).

46. Saffran, J. R. Constraints on statistical language learning. J. Mem. Lang. 47, 172-196 (2002). This study shows that learners can use the predictive relationships that link elements within phrases to acquire phrase structure. Predictive relationships improved learning for sequentially presented auditory stimuli, and for simultaneously presented visual stimuli, but not for sequentially presente......

47. Goodsitt, J. V., Morgan, J. L. & Kuhl, P. K. Perceptual strategies in prelingual speech segmentation. J. Child Lang. 20, 229-252 (1993).

48. Karzon, R. Discrimination of polysyllabic sequences by oneto four-month-old infants. J. Exp. Child Psychol. 39, 326-342 (1985).

49. Saffran, J. R., Aslin, R. N. & Newport, E. L. Statistical learning by 8-month old infants. Science 274, 1926-1928 (1996).

50. Aslin, R. N., Saffran, J. R. & Newport, E. L. Computation of conditional probability statistics by 8-month-old infants. Psychol. Sci. 9, 321-324 (1998).

51. Saffran, J. R., Johnson, E. K., Aslin, R. N. & Newport, E. L. Statistical learning of tone sequences by human infants and adults. Cognition 70, 27-52 (1999).

52. Fiser, J. & Aslin, R. N. Statistical learning of new visual feature combinations by infants. Proc. Natl Acad. Sci. USA 99, 15822-15826 (2002).

53. Kirkham, N. Z., Slemmer, J. A. & Johnson, S. P. Visual statistical learning in infancy: evidence for a domain general learning mechanism. Cognition 83, B35-B42 (2002). This study provides evidence that infants' statistical learning from auditory input can be generalized to the visual domain.

54. Hauser, M. D., Newport, E. L. & Aslin, R. N. Segmentation of the speech stream in a non-human primate: statistical learning in cotton-top tamarins. Cognition 78, B53-B64 (2001).

55. Cutler, A. & Carter, D. The predominance of strong initial syllables in the English vocabulary. Comput. Speech Lang. 2, 133-142 (1987).

56. Jusczyk, P. W., Houston, D. M. & Newsome, M. The beginnings of word segmentation in English-learning infants. Cognit. Psychol. 39, 159-207 (1999).

57. Johnson, E. K. & Jusczyk, P. W. Word segmentation by 8-month-olds: when speech cues count more than statistics. J. Mem. Lang. 44, 548-567 (2001). The authors showed that, when multiple cues are available, 8-month-olds weighed prosodic cues more heavily than statistical cues.

58. Saffran, J. R. & Thiessen, E. D. Pattern induction by infant language learners. Dev. Psychol. 39, 484-494 (2003). A study of how infants segment words according to stress patterns. Nine-month-old infants learned to segment speech using the iambic pattern whether the exposure consisted of 100% or 80% iambic words. Seven-month-olds could alter their segmentation strategies when the distribution ......

59. Thiessen, E. D. & Saffran, J. R. Learning to learn: infants' acquisition of stress-based strategies for word segmentation. J. Mem. Lang. (under revision).

60. Santelmann, L. M. & Jusczyk, P. W. Sensitivity to discontinuous dependencies in language learners: evidence for limitations in processing space. Cognition 69, 105-134 (1998).

61. Silva-Pereyra, J., Rivera-Gaxiola, M. & Kuhl, P. K. An eventrelated brain potential study of sentence comprehension in preschoolers: semantic and morphosyntatic processing. Cognit. Brain Res. (in the press).

62. Newport, E. L. & Aslin, R. N. Learning at a distance I. Statistical learning of non-adjacent dependencies. Cognit. Psychol. 48, 127-162 (2004).

63. Newport, E. L., Hauser, M. D., Spaepen, G. & Aslin, R. N. Learning at a distance II. Statistical learning of non-adjacent dependencies in a non-human primate. Cognit. Psychol. 49, 85-117 (2004).

64. Gomez, R. L. & Gerken, L. Artificial grammar learning by 1-year-olds leads to specific and abstract knowledge. Cognition 70, 109-135 (1999).

65. Gomez, R. L. & Gerken, L. Infant artificial language learning and language acquisition. Trends Cogn. Sci. 4, 178-186 (2000).

66. Pena, M., Bonatti, L. L., Nespor, M. & Mehler, J. Signaldriven computations in speech processing. Science 298, 604-607 (2002).

67. Marcus, G. F., Vijayan, S., Bandi Rao, S. & Vishton, P. M. Rule learning by seven-month-old infants. Science 283, 77-80 (1999).

68. Seidenberg, M. S., MacDonald, M. C. & Saffran, J. R. Does grammar start where statistics stop? Science 298, 553-554 (2002).

69. Seidenberg, M. S. & Elman, J. Do infants learn grammar with algebra or statistics? Science 284, 433 (1999).

70. Doupe, A. J. & Kuhl, P. K. Birdsong and human speech: common themes and mechanisms. Annu. Rev. Neurosci. 22, 567-631 (1999).

71. Kuhl, P. K. Human speech and birdsong: communication and the social brain. Proc. Natl Acad. Sci. USA 100, 9645-9646 (2003).

72. Fromkin, V., Krashen, S., Curtiss, S., Rigler, D. & Rigler, M. The development of language in Genie: a case of language acquisition beyond the `critical period'. Brain Lang. 1, 81-107 (1974).

73. Kuhl, P. K., Coffey-Corina, S., Padden, D. M. & Dawson, G. Links between social and linguistic processing of speech in preschool children with autism: behavioral and electrophysiological measures. Dev. Sci. 7, 19-30 (2004).

74. Vouloumanos, A. & Werker, J. F. Tuned to the signal: the privileged status of speech for young infants. Dev. Sci. 7, 270-276 (2004). The authors investigated differences in 2to 7-month old infants' perception of nonsense speech sounds and structurally similar non-speech analogues. They found a bias for speech sounds in infants as young as 2-months old.

75. Bruner, I. Child's Talk: Learning to Use Language (W. W. Norton, New York, 1983).

76. Vigotsky, L. S. Thought and Language: A Usage-Based Theory of Language Acquisition (MIT Press, Cambridge, Massachusetts, 1962).

77. Tomasello, M. Constructing a Language (Harvard Univ. Press, Cambridge, Massachusetts, 2003).

78. Fernald, A. & Kuhl, P. Acoustic determinants of infant preference for motherese speech. Infant Behav. Dev. 10, 279-293 (1987).

79. Kuhl, P. K. et al. Cross-language analysis of phonetic units in language addressed to infants. Science 277, 684-686 (1997).

80. Goldstein, M., King, A. & West, M. Social interaction shapes babbling: testing parallels between birdsong and speech. Proc. Natl Acad. Sci. USA 100, 8030-8035 (2003).

81. Bloom, K. Social elicitation of infant vocal behavior. J. Exp. Child Psychol. 20, 51-58 (1975).

82. Bloom, K. & Esposito, A. Social conditioning and its proper control procedures. J. Exp. Child Psychol. 19, 209-222 (1975).

83. Eales, L. The influences of visual and vocal interaction on song learning in zebra finches. Anim. Behav. 37, 507-508 (1989).

84. Immelmann, K. in Bird Vocalizations (ed. Hinde, R.) 61-74 (Cambridge Univ. Press, London, 1969).

85. Baptista, L. F. & Petrinovich, L. Song development in the white-crowned sparrow: social factors and sex differences. Anim. Behav. 34, 1359-1371 (1986).

86. Brainard, M. S. & Knudsen, E. I. Sensitive periods for visual calibration of the auditory space map in the barn owl optic tectum. J. Neurosci. 18, 3929-3942 (1998).

87. West, M. & King, A. Female visual displays affect the development of male song in the cowbird. Nature 334, 244-246 (1988).

88. Nelson, D. & Marler, P. Selection-based learning in bird song development. Proc. Natl Acad. Sci. USA 91, 10498-10501 (1994).

89. Adret, P. Operant conditioning, song learning and imprinting to taped song in the zebra finch. Anim. Behav. 46, 149-159 (1993).

90. Tchernichovski, O., Mitra, P., Lints, T. & Nottebohm, F. Dynamics of the vocal imitation process: how a zebra finch learns its song. Science 291, 2564-2569 (2001).

91. Brooks, R. & Meltzoff, A. N. The importance of eyes: how infants interpret adult looking behavior. Dev. Psychol. 38, 958-966 (2002).

92. Baldwin, D. A. in Joint Attention: Its Origins and Role in Development (eds Moore, C. & Dunham, P. J.) 131-158 (Lawrence Erlbaum Associates, Hillsdale, New Jersey, 1995).

93. Mundy, P. & Gomes, A. Individual differences in joint attention skill development in the second year. Infant Behav. Dev. 21, 469-482 (1998).

94. Kuhl, P. K. & Meltzoff, A. N. The bimodal perception of speech in infancy. Science 218, 1138-1141 (1982).

95. Bloom, K., Russell, A. & Wassenberg, K. Turn taking affects the quality of infant vocalizations. J. Child Lang. 14, 211-227 (1987).

96. Liu, H.-M., Kuhl, P. K. & Tsao, F.-M. An association between mothers' speech clarity and infants' speech discrimination skills. Dev. Sci. 6, F1-F10 (2003).

97. Thiessen, E. D., Hill, E. & Saffran, J. R. Infant-directed speech facilitates word segmentation. Infancy (in the press).

98. Marler, P. in The Epigenesis of Mind: Essays on Biology and Cognition (eds Carey, S. & Gelman, R.) 37-66 (Lawrence Erlbaum Associates, Hillsdale, New Jersey, 1991).

99. Evans, C. S. & Marler, P. in Comparative Approaches to Cognitive Science: Complex Adaptive Systems (eds Roitblat, H. L. & Meyer, J.-A.) 341-382 (MIT Press, Cambridge, Massachusetts, 1995).

100. Petitto, L. A., Holowka, S., Sergio, L. E., Levy, B. & Ostry, D. J. Baby hands that move to the rhythm of language: hearing babies acquiring sign language babble silently on the hands. Cognition 93, 43-73 (2004). This study showed that hearing babies acquire sign language `babble' with their hands in a way that differs from hearing babies acquiring spoken language.

101. Kuhl, P. K., Williams, K. A. & Meltzoff, A. N. Cross-modal speech perception in adults and infants using nonspeech auditory stimuli. J. Exp. Psychol. Hum. Percept. Perform. 17, 829-840 (1991).

102. Meltzoff, A. N. Understanding the intentions of others: re-enactment of intended acts by 18-month-old children. Dev. Psychol. 31, 838-850 (1995).

103. Adolphs, R. Cognitive neuroscience of human social behaviour. Nature Rev. Neurosci. 4, 165-178 (2003).

104. Dunbar, R. I. M. The social brain hypothesis. Evol. Anthropol. 6, 178-190 (1998).

105. Knightly, L. M., Jun, S.-A., Oh, J. S. & Au, T. K.-F. Production benefits of childhood overhearing. J. Acoust. Soc. Am. 114, 465-474 (2003).

106. Funabiki, Y. & Konishi, M. Long memory in song learning by zebra finches. J. Neurosci. 23, 6928-6935 (2003).

107. Wilbrecht, L. & Nottebohm, F. Vocal learning in birds and humans. Ment. Retard. Dev. Disabil. Res. Rev. 9, 135-148 (2003).

108. Nottebohm, F. The road we travelled: discovery, choreography, and significance of brain replaceable neurons. Ann. NY Acad. Sci. 1016, 628-658 (2004).

109. Dehaene-Lambertz, G., Dupoux, E. & Gout, A. Electrophysiological correlates of phonological processing: a cross-linguistic study. J. Cogn. Neurosci. 12, 635-647 (2000).

110. Callan, D. E., Jones, J. A., Callan, A. M. & Akahane-Yamada, R. Phonetic perceptual identification by nativeand secondlanguage speakers differentially activates brain regions involved with acoustic phonetic processing and those involved with articulatory-auditory/orosensory internal models. Neuroimage 22, 1182-1194 (2004).

111. Zhang, Y., Kuhl, P. K., Imada, T. & Kotani, M. Effects of language experience: where, when & how. Cognitive Neuroscience Society Annual General Meeting program 2003, 81-82.

112. Sanders, L. D., Newport, E. L. & Neville, H. J. Segmenting nonsense: an event-related potential index of perceived onsets in continuous speech. Nature Neurosci. 5, 700-703 (2002).

113. Golestani, N. & Zatorre, R. J. Learning new sounds of speech: reallocation of neural substrates. Neuroimage 21, 494-506 (2004).

114. Wang, Y., Sereno, J. A., Jongman, A. & Hirsch, J. fMRI evidence for cortical modification during learning of Mandarin lexical tone. J. Cogn. Neurosci. 15, 1019-1027 (2003).

115. Winkler, I. et al. Brain responses reveal the learning of foreign language phonemes. Psychophysiology 36, 638-642 (1999).

116. Koyama, S. et al. Cortical evidence of the perceptual backward masking effect on /l/ and /r/ sounds from a following vowel in Japanese speakers. Neuroimage 18, 962-974 (2003).

117. Temple, E. et al. Neural deficits in children with dyslexia ameliorated by behavioral remediation: evidence from functional MRI. Proc. Natl Acad. Sci. USA 100, 2860-2865 (2003). This fMRI study of children with dyslexia showed that an auditory processing and oral language remediation programme produced increased brain activity in areas that are usually activated in children who have no diffic......

118. Cheour, M. et al. Magnetoencephalography (MEG) is feasible for infant assessment of auditory discrimination. Exp. Neurol. (in the press).

119. Dehaene-Lambertz, G., Dehaene, S. & Hertz-Pannier, L. Functional neuroimaging of speech perception in infants. Science 298, 2013-2015 (2002). The authors used fMRI to show that, like adults, language activates areas in the left hemisphere, with additional activation in the preforntal cortex of awake infants.

120. Pena, M. et al. Sounds and silence: an optical topography study of language recognition at birth. Proc. Natl Acad. Sci. USA 100, 11702-11705 (2003).

121. Mills, D. L., Coffey-Corina, S. & Neville, H. J. Language comprehension and cerebral specialization from 13-20 months. Dev. Neuropsychol. 13, 397-445 (1997).

122. Kuhl, P. K. A new view of language acquisition. Proc. Natl Acad. Sci. USA 97, 11850-11857 (2000).

123. Dehaene, S., Spelke, E., Pinel, P., Stanescu, R. & Tsivkin, S. Sources of mathematical thinking: behavioral and brain-imaging evidence. Science 284, 970-974 (1999).

124. Iverson, P. et al. A perceptual interference account of acquisition difficulties for non-native phonemes. Cognition 87, B47-B57 (2003).

125. Friederici, A. D. & Wessels, J. M. I. Phonotactic knowledge of word boundaries and its use in infant speech perception. Percept. Psychophys. 54, 287-295 (1993).

126. Mattys, S., Jusczyk, P., Luce, P. & Morgan, J. L. Phonotactic and prosodic effects on word segmentation in infants. Cognit. Psychol. 38, 465-494 (1999).

127. Werker, J. F., Fennell, C., Corcoran, K. & Stager, C. Infants' ability to learn phonetically similar words: effects of age and vocabulary size. Infancy 3, 1-30 (2002). This study showed that 14-month-old infants could not learn to pair phonetically similar words with different objects, whereas 20-month-old infants could. Vocabulary size was a predictive factor in the younger infants.

128. Stager, C. & Werker, J. F. Infants listen for more phonetic detail in speech perception than in word-learning tasks. Nature 388, 381-382 (1997).

129. Morgan, J. L. & Demuth, K. Signal to Syntax: Bootstrapping from Speech to Grammar in Early Acquisition (Lawrence Erlbaum Associates, Hillsdale, New Jersey, 1996).

130. Tsao, F. M., Liu, H. M. & Kuhl, P. K. Speech perception in infancy predicts language development in the second year of life: a longitudinal study. Child Dev. 75, 1067-1084 (2004).

131. Pang, E. et al. Mismatch negativity to speech stimuli in 8-month-old infants and adults. Int. J. Psychophysiol. 29, 227-236 (1998).

132. Kuhl, P. K., Nelson, T., Coffey-Corina, S., Padden, D. M. & Conboy, B. Early brain and behavioral measures of native and non-native speech perception differentially predict later language development: the neural commitment hypothesis. Soc. Neurosci. Abstr. 15935 (2004).

133. Knudsen, E. I. in Fundamental Neuroscience (ed. Zigmond, M. J.) 637-654 (Academic, San Diego, 1999).

134. Lenneberg, E. H. Biological Foundations of Language (Wiley, New York, 1967).

135. Newport, E. Maturational constraints on language learning. Cognit. Sci. 14, 11-28 (1990).

136. Johnson, J. & Newport, E. Critical period effects in sound language learning: the influence of maturation state on the acquisition of English as a second language. Cognit. Psychol. 21, 60-99 (1989).

137. Piske, T., MacKay, I. & Flege, J. Factors affecting degree of foreign accent in an L2: a review. J. Phonetics 29, 191-215 (2001).

138. Long, M. Maturational constraints on language development. Stud. Second Lang. Acquis. 12, 251-285 (1990).

139. Birdsong, D. & Molis, M. On the evidence for maturational constraints in second-language acquisition. J. Mem. Lang. 44, 235-249 (2001).

140. Flege, J. E., Yeni-Komshian, G. H. & Liu, S. Age constraints on second-language acquisition. J. Mem. Lang. 41, 78-104 (1999). A study of second language learning in Korean speakers who arrived in the United States at different ages. Age of arrival in the United States predicted the strength of perceived foreign accent, but grammaticality scores were more related to education and use of Englis......

141. Mayberry, R. I. & Lock, E. Age constraints on first versus second language acquisition: evidence for linguistic plasticity and epigenesis. Brain Lang. 87, 369-84 (2003).

142. Greenough, W. T. & Black, J. E. in The Minnesota Symposia on Child Psychology, Vol. 24: Developmental Behavioral Neuroscience (eds Gunnar, M. & Nelson, C.) 155-200 (Lawrence Erlbaum Associates, Hillsdale, New Jersey, 1992).

143. Oh, J. S., Jun, S.-A., Knightly, L. M. & Au, T. K.-F. Holding on to childhood language memory. Cognition 86, B53-B64 (2003).

144. Au, T. K.-F., Knightly, L. M., Jun, S.-A. & Oh, J. S. Overhearing a language during childhood. Psychol. Sci. 13, 238-243 (2002). This study showed that adults speak a second language with a more native-like accent if they overheard the language regularly during childhood.

145. Pallier, C. et al. Brain imaging of language plasticity in adopted adults: can a second language replace the first? Cereb. Cortex 13, 155-161 (2003).

146. Flege, J., Bohn, O. & Jang, S. Effects of experience on non-native speakers' production and perception of English vowels. J. Phonetics 25, 437-470 (1997).

147. Morgan, J. L., Meier, R. & Newport, E. L. Structural packaging in the input to language learning: contributions of intonational and morphological marking of phrases to the acquisition of language. Cognit. Psychol. 19, 498-550 (1987).

148. Saffran, J. R. Statistical language learning: mechanisms and constraints. Curr. Dir. Psychol. Sci. 12, 110-114 (2003).

149. Hauser, M. D., Chomsky, N. & Fitch, W. T. The faculty of language: what is it, who has it, and how did it evolve? Science 298, 1569-1579 (2002).