A new view of language acquisition

Abstract

At the forefront of debates on language are new data demonstrating infants' early acquisition of information about their native language. The data show that infants perceptually "map" critical aspects of ambient language in the first year of life before they can speak. Statistical properties of speech are picked up through exposure to ambient language. Moreover, linguistic experience alters infants' perception of speech, warping perception in the service of language. Infants' strategies are unexpected and unpredicted by historical views. A new theoretical position has emerged, and six postulates of this position are described.

Figure 1

Vocal tract positions (Upper) and spectrographic displays (Lower) for the vowels/i/as in “heat” and/a/as in “hot.” Formant frequencies, regions of the frequency spectrum in which the concentration of energy is high, are marked for each vowel.

Figure 2

Spectrographic display of running speech showing the formant frequencies and the pitch (fundamental frequency) of the voice over time. Increases in pitch indicate primary stress in the utterance. [Reproduced with permission from ref. (Copyright 1999, Allyn & Bacon).]

Figure 3

Humans' and animals' identification functions for two series ranging from a voiced to a voiceless phonetic unit (/d/to/t/and/g/to/k/) showing that animals' perceptual boundaries correspond to humans' phonetic boundaries. VOT, voice onset time. [Reproduced with permission from ref. (Copyright 1978, Acoustical Society of America).]

Figure 4

Monkey discrimination performance for pairs of stimuli drawn from a continuum of speech sounds ranging from/b/to/d/to/g/, showing that sensitivity increases near the locations of humans' phonetic boundaries. [Reproduced with permission from ref. (Copyright 1978, Acoustical Society of America.]

Figure 5

(A) Formant frequencies of vowels surrounding an American/i/prototype (red) and a Swedish/y/prototype (blue). (B) Results of tests on American and Swedish infants indicating an effect of linguistic experience. Infants showed greater generalization when tested with the native-language prototype. PME, Perceptual magnet effect. [Reproduced with permission from ref. (Copyright 1992, American Association for the Advancement of Science).]

Figure 6

(A) Physical distance between/ra-la/syllables in a grid created by varying formants 2 and 3 in equal steps. (B) Perceptual distance between syllables for American listeners showing a warping of acoustic space. MDS, Multidimensional scaling. [Reproduced with permission from ref. (Copyright 1996, Acoustical Society of America).]

Figure 7

Infants' vowels recorded as they imitate an adult show developmental change between 12 and 20 weeks of age. [Reproduced with permission from ref. (Copyright 1996, Acoustical Society of America).]

Figure 8

Formant frequencies for vowels produced by American (A) and Russian (B) mothers as they talked to their infants (solid symbols) and to another adult (open symbols), indicating that vowels in infant-directed speech are acoustically exaggerated. [Reproduced with permission from ref. (Copyright 1997, American Association for the Advancement of Science).]