Infants’ use and weighting of prosodic cues in clause segmentation

This paper investigates the acoustic properties of speech used by infant listeners to discover clauses in continuous speech. In a series of experiments using the Headturn Preference procedure, 6-month-old infants’ use and weighting of prosodic cues in their segmentation of clauses in continuous speech was explored. The experiments sequentially featured each of three acoustic correlates of syntactic boundaries (pause duration, pitch, and preboundary lengthening) and examined whether infants’ performance on clause segmentation tasks remained the same or was degraded as the result of the loss of one or more of these correlates of a syntactic boundary. In this way, information concerning the perceptual weighting of these cues was elucidated. Results of these experiments suggest that while pitch is a necessary cue for 6-month-old English-learning infants, it is not a sufficient cue to segment clauses. Rather, the converging cues of pitch and pause or pitch and preboundary length are necessary. These results suggest that, although infants do not seem to weight these prosodic cues the same as adult listeners do, nonetheless, by 6 months of age they have already become attuned to some of the weighting of prosodic cues present in their input language and do not treat all cues equally.