Sixteen-month-old infants’ segment words from infant- and adult-directed speech

One of the first challenges facing the young language learner is the task of segmenting words from a natural language speech stream, without prior knowledge of how these words sound. Studies with younger children find that children find it easier to segment words from fluent speech when the words are presented in infant-directed speech, i.e., the kind of speech typically directed toward infants, compared to adult-directed speech. The current study examines whether infants continue to display similar differences in their segmentation of infant- and adult-directed speech later in development. We show that 16-month-old infants successfully segment words from a natural language speech stream presented in the adult-directed register and recognize these words later when presented in isolation. Furthermore, there were no differences in infants’ ability to segment words from infant- and adult-directed speech at this age, although infants’ success at segmenting words from adult-directed speech correlated with their vocabulary size.