The perception of boundary tones in infancy

We investigated English-learning 4-month-olds’ ability to discriminate a final rise versus fall in pitch that distinguishes questions from statements in Portuguese and English. Using visual habituation, we showed that English-learning 4-month-olds failed to categorize segmentally varied Portuguese statements vs. questions. They only succeeded when tested with restricted segmental variability in a more sensitive procedure. Finally, we showed that Basque-learning 4-month-olds have no difficulty categorizing Portuguese statements and questions. Thus, unlike their Portuguese-learning peers, English-learning 4-mo-olds are limited in their ability to distinguish Portuguese statements vs. questions. This is not simply because of the use of non-native speech stimuli, as demonstrated by the success of the Basque infants. This implies that infants’ perception of boundary tones is already language-specific at 5-months. Additionally, our results provide a way to reconcile previous puzzling findings about English-learning infants’ difficulty in categorizing English statements from questions.