The shift in infant preferences for vowel duration and pitch contour between 6 and 10 months of age
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Updated: Jun 20, 2026

Exploring Infant Sensitivity to Visual Language using Eye Tracking and the Preferential Looking Paradigm
Published on: May 15, 2019
Christine Kitamura1, Anna Notley
1MARCS Auditory Laboratories, University of Western Sydney, Sydney, NSW, Australia. c.kitamura@uws.edu.au
Abstract:
This study investigates the influence of the acoustic properties of vowels on 6- and 10-month-old infants' speech preferences. The shape of the contour (bell or monotonic) and the duration (normal or stretched) of vowels were manipulated in words containing the vowels /i/ and /u/, and presented to infants using a two-choice preference procedure. Experiment 1 examined contour shape: infants heard either normal-duration bell-shaped and monotonic contours, or the same two contours with stretched duration. The results show that 6-month-olds preferred bell to monotonic contours, whereas 10-month-olds preferred monotonic to bell contours. In Experiment 2, infants heard either normal-duration and stretched bell contours, or normal-duration and stretched monotonic contours. As in Experiment 1, infants showed age-specific preferences, with 6-month-olds preferring stretched vowels, and 10-month-olds preferring normal-duration vowels. Infants' attention to the acoustic qualities of vowels, and to speech in general, undergoes a dramatic transformation in the final months of the first year, a transformation that aligns with the emergence of other developmental milestones in speech perception.
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