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…

Seven 18- to 32-month-old children received from seven to 26 experimental sessions each between October 1966 and April 1967. A session lasted from 5 to 15 minutes and concerned control over the verbal responses of the children with token-operated reinforcement devices. In order to make the results of the experimental sessions meaningful, an…

The range of meanings of "big" and "little" that mothers and their three children under age two expressed in relatively natural communication situations was studied. Longitudinal data from transcripts of conversations of middle-class mothers and their children were analyzed along with diary records kept by parents of their children's use of size…