The role of exposure to isolated words in early vocabulary development

Fluent speech contains no known acoustic analog of the blank spaces between printed words. Early research presumed that word learning is driven primar ily by exposure to isolated words. In the last decade there has been a shif t to the view that exposure to isolated words is unreliable and plays littl e if any role in early word learning. This study revisits the role of isola ted words. The results show (a) that isolated words are a reliable feature of speech to infants, (b) that they include a variety of word types, many o f which are repeated in close temporal proximity, (c) that a substantial fr action of the words infants produce are words that mothers speak in isolati on, and (d) that the frequency with which a child hears a word in isolation predicts whether that word will be learned better than the child's total f requency of exposure to that word. Thus, exposure to isolated words may sig nificantly facilitate vocabulary development at its earliest stages. (C) 20 01 Elsevier Science B.V. All rights reserved.