Project Overview

  • Status: COMPLETE
  • 69 participating labs in 16 countries
  • 2,329 babies tested
  • 149 authors on AMPPS publication
  • Project data, analysis code, and materials available on OSF

In the first ManyBabies project, we replicated a robust finding from developmental literature: infants’ preference for infant-directed speech (IDS) over adult-directed speech (ADS). IDS is characterized by a higher pitch, greater pitch excursions, and shorter utterances when compared to ADS. Exposure to IDS has been shown to improve word segmentation and word learning. We asked if infants have a preference for IDS, and how this preference varies across age, native language background, and method.

Sixty-nine labs from 16 countries participated and collected data from 2,329 infants (range: 3-15 months old). We focused on three primary methods for assessing infants’ interest: single-screen central fixation, eye tracking, and the head-turn preference procedure (HPP).


  • Confirmed the existence of an IDS preference in infant listeners
  • IDS preference was significantly stronger in older children, in those children for whom the stimuli matched their native language and dialect (North American English, or NAE), and in data from labs using the head-turn preference procedure (magnitude of 0.05 SDs per month), suggesting a modulation by experience, maturation, or both
  • IDS preference for NAE stimuli even among participants whose native language or dialect was not NAE
  • Effect was strongest with the HPP than with the central-fixation or eye-tracking approaches.
  • One potential interpretation of this finding is that the greater effort on the part of the infant in the HPP (i.e., turning the head, as opposed to making small eye movements) leads to stronger engagement in the task and therefore to stronger effects

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