Infants' vocalizations at 6 months predict their productive vocabulary at one year.

Long before their first words, children communicate by using speech-like vocalizations. These protophones might be indicative of infants' later language development. We here examined infants' (n = 56) early vocalizations at 6 months (vocal reactivity scale of the IBQ-R) as a predictor of their expressive and receptive language at 12 months (German version of the CDI). Regression analyses revealed vocalizations to significantly predict expressive, but not receptive language. Our findings in German-learning 6-month-olds extend previous predictive evidence of early vocalizations reported for older infants. Together these findings are informative in light of early assessments monitoring typical and atypical language development.