Sixteen-Month-Old Infants’ Segment Words from Infant- and Adult-Directed Speech

ABSTRACT

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.

Notes

¹ Due to experimenter oversight, more children were tested using ADS than using the IDS stimuli. To ensure that this did not lead to an exaggerated effect in the ADS condition, we ran a separate analysis where the analysis software (SPSS) chose a random sample of 24 children (the number of children tested in the IDS condition). We found a main effect of condition (F(1, 46) = 9.90, p = .003; η_p²=.17) and no main effect of register or interaction between register and condition (ps > .3). Once again, infants in the ADS condition listened longer to lists of familiar words relative to unfamilar words (t(23) = −2.1, p = .042; d = .44).

² Note this only included data from 20 children in the ADS condition and 23 children in the IDS condition since some parents did not return the completed communicative development inventory.