Lexical Development in Human Infants

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921064 The purpose of this research is to reveal the lexical-recognition competencies of normal human infants during the second six months of postnatal development. The focus of the research is on the perceptual and memory abilities required for the segmentation and extraction of words (or wordlength units) from fluent maternal speech prior to the onset-age of vocal production. A new familiarization-preference (F-Pref) technique has been developed to assess infants' sensitivities to words. This technique involves a brief familiarization period (30-45 seconds) during which infants are presented with target words (or non-words) embedded in sentences and subsequently tested for recognition of those words in isolation compared to non-familiar words. Postfamiliarization recognition is revealed by longer listening times to familiar over non-familiar words. This technique will be used to explore further the conditions under which 7 to 8 month old infants are able to extract words from fluent speech when the surrounding acoustic, phonetic, and language-specific contexts are varied, when speaking rate is altered, and when the frequency of pauses is manipulated during the familiarization period. In addition to these primary questions, we will also attempt to extend the F-Pref technique to infants in the first six months of postnatal development (using simplified procedures), and to older infants in an attempt to reveal the emergence of semantic priming in infancy. Because the segmentation, extraction, and memory for words embedded in fluent speech is a necessary precursor to the formation of a lexicon, these experiments should reveal a fundamental capacity of infants in the early stage of language acquisition when comprehension is thought to be superior to production.