Examines the timing of partners' talk in mother-infant engagements over infant age to determine whether variations occur in the incidence of the alternating mode. Findings reflect the facilitative effects of covocalization in preverbal infants and the need for the alternating mode with older infants. (31 references) (Author/CK)

The ontogenetic development of human vocal utterances and their role in early interaction processes were studied with a three-month-old baby. Recordings were made of infant vocalizations in the home and the sounds were classified. During a five-minute segment between the mother and infant, the infant produced 59 utterances, 93 percent of which had…