Infant vocal-motor coordination: precursor to the gesture-speech system?

This study was designed to provide a general picture of infant vocal-motor coordination and test predictions generated by Iverson and Thelen's (1999) model of the development of the gesture-speech system. Forty-seven 6- to 9-month-old infants were videotaped with a primary caregiver during rattle and toy play. Results indicated an age-related increase in frequency of vocal-motor coordination, greater coordination with arm (specifically right arm) than leg or torso movements, and a temporal pattern similar to that in adult gesture-speech coproductions. Rhythmic vocalizations (consonant-vowel repetitions) were more likely to occur with than without rhythmic movement, and with rhythmic manual than with nonmanual activity, and the rate of vocal-manual coordination was higher in babblers than in prebabblers.