What Mothers Do After Infants Vocalize: Implications for Vocal Development or Word Learning?

Purpose The goal of this study was to analyze verbal and nonverbal maternal response types following infant vocalizations in younger (ages 4-8 months) versus older (ages 10-14 months) infant groups and their potential implications for infant vocal development or word learning. Method Maternal response types that occurred within 3 s of infant vocalizations were examined in this cross-sectional study of naturalistic interactions in 35 mother-infant dyads. Response types were defined as vocally responsive to infant vocalizations (i.e., responsive vocal behaviors), not responsive to infant vocalizations directly (nonresponsive vocal behaviors), and silences. Mothers' nonverbal actions associated with each response type were also examined. Subcategories of these verbal and nonverbal response types were examined in relation to infant age group. Results The occurrence of responsive and nonresponsive verbal subcategory types differed by infant age group. When verbally responsive to infant vocalizations, mothers commented on younger infants' vowel and consonant-vowel vocalizations, but with older infants, mothers identified or named the referents of their vocalizations. When nonresponsive to vocalizations directly, mothers commented on younger infants' activities but redirected older infants' behaviors or commented on their movements. Silence after infant vocalizations was infrequent. Mothers' nonverbal actions associated with each response type were primarily object related and did not differ by age group. Conclusions Evaluating response type subcategories by age group indicated mothers did not respond differentially (verbally or nonverbally) to vowel or consonant-vowel vocalizations. Overall, the results suggest mothers' verbal and nonverbal response types may be more likely to facilitate word learning than vocal development.