THE DEVELOPMENT OF LANGUAGE SKILLS IN P/ilV- II< PRODUCTION

Introduction We humans have long held great stock in our ability to use language to communicate with one another. Language is a powerful tool that allows us to coordinate behavior, discuss things remote in time and place, and write manuscripts such as this one. It has played a vital role in the success of our species and it is such an integral part of our individual lives that it is intimately tied to our very thought. Such being the case, language acquisition has received considerable attention from the psychological research community. Many measures of linguistic competency have been presented over the years, including examinations of lexicon growth (Dromi, 1987; Fenson et al., 1994), vocabulary content (Nelson, 1973; Bates et al., 1979) word combination and syntax development (Bates et al., 1988; Bloom, 1973, 1991), and pragmatic or contextual dimensions of word use (Bruner, 1983; Greenfield and Smith, 1976; McShane, 1980).’ Although the specific patterns and timing of different children’s mastery of language vary among individuals (Nelson, 1973; Fenson et al., 1994), some rough generalizations are possible in reference to the classical model of ‘typical’ language acquisition. With regard to productive indices, a child begins to make prelinguistic vocalizations (‘babbling’) around 7 months of age (Stark, 1980). At the end of the first year, communicative intentionality develops (Bates et al., 1975) and gestures as well as word-like sounds or ‘protowords’ (Adamson, 1995) may provide a bridge between babbling and true word production. First words typically appear between 10 and 13 months (Bates et al., 1979), followed by a period of single-word use and vocabulary growth, often with a vocabulary ‘spurt’ at about 1; years of age when the child’s productive lexicon is around 50 words (Fenson et al., 1994; Nelson, 1973). As the vocabulary starts to increase rapidly, often at a rate of more than one word per day (Fenson et al., 1994), word combinations also start to appear during the second half of the child’s second year. After just a few e years of life, the child is well on its way to mastering the multiple aspects of human language. As an infant grows and acquires linguistic competency, he or she expresses three developmental processes outlined by Vygotsky and Luria (1993) many years ago but receiving renewed interest in recent years (Lerner, 1984; Parker, 1990): ontogeny, which guides the individual’s growth as he or she matures and interacts with others; cultural history, which allows the individual to benefit from knowledge and traditions accumulated over uncounted generations; and phylogeny, which has provided the human species with the