Constraints on infant speech acquisition : a cross-language perspective

This study explored the relative contributions of child-internal production factors and perceptual influences from the ambient language on early speech-+ acquisition. Research has suggested that both articulatory complexity and perceptual distinctiveness impact a language's phonetic inventory; however, the ways these two properties interact during speech acquisition is not well understood. Quichua, spoken in Highland Ecuador, differs from English in many phonological properties. Babbling and early words of seven Quichua-learning infants between 9 and 16 months at the onset were followed longitudinally for 6 months. They were compared to the babbling and early words of Englishlearning infants and to Quichua and English adult speech samples. Production factors predominated in the babbling and early words of the Quichua infants. The infants' productions in the two language environments were more similar than the Quichua infants' speech productions were to the Quichua adult language models. Infants from both language environments primarily produced coronal stops and nasals, lower left quadrant vowels, simple consonantvowel syllables, one-syllable utterances, as well as similar predicted intrasyllabic consonant-vowel co-occurrence and intersyllabic consonant-consonant and vowel-vowel variegation patterns. Evidence of ambient language influences was apparent in consonant and vowel inventories and utterance length in the older infants. Dorsals, fricatives, and affricates occurred more frequently, and labials and liquids occurred less frequently in Quichua than English-learning infants. Quichua infants also produced more low vowels in late babbling and more two- and three-or-more syllable words. These findings all mirror Quichua properties. In addition, the Quichua infants' lower level of word use and shorter babbling length appear to reflect cultural influences. These findings indicate that child-internal production factors, ambient language influences and cultural norms must all be considered in an attempt to understand early speech acquisition. Many of the production patterns observed in the infants' utterances also occurred in the adult ambient language, although not to the same extent as in the infants. Based on the parallel findings in infants and adults, it appears that production-based factors are a principle underlying factor in babbling and first words, and are so basic to the production mechanism that they are retained to a lesser extent in modern languages.