The acoustic salience of prosody trumps infants' acquired knowledge of language-specific prosodic patterns.

There is mounting evidence that prosody facilitates grouping the speech stream into syntactically-relevant units (e.g., Hawthorne & Gerken, 2014; Soderstrom, Kemler Nelson, & Jusczyk, 2005). We ask whether prosody's role in syntax acquisition relates to its general acoustic salience or to the learner's acquired knowledge of correlations between prosody and syntax in her native language. English- and Japanese-acquiring 19-month-olds listened to sentences from an artificial grammar with non-native prosody (Japanese or English, respectively), then were tested on their ability to recognize prosodically-marked constituents when the constituents had moved to a new position in the sentence. Both groups were able to use non-native prosody to parse speech into cohesive, reorderable, syntactic constituent-like units. Comparison with Hawthorne & Gerken (2014), in which English-acquiring infants were tested on sentences with English prosody, suggests that 19-month-olds are equally adept at using native and non-native prosody for at least some types of learning tasks and, therefore, that prosody is useful in early syntactic segmentation because of its acoustic salience.