Generalized vocal imitation in infants.

Effects of modeling and response-contingent social praise on the vocal imitation of three 9- to 13-month-old infants were analyzed. Three infants and parents participated in 2 to 4 experimental sessions a week for 2 to 4 months. During each 20-min-long session, the parent presented vocal models for the infant to imitate. During the model-alone condition, no social praise was programmed for infant imitation. During the model-and-praise condition, social praise was provided by the parent for infant imitation on training trials, but not probe trials. All three infants showed systematic increases in matching during training trials following the introduction of the model-and-praise condition. Although matching during probe trials was not directly reinforced, probe-trial responding increased systematically with training-trial responding. Furthermore, non-matching infant vocalizations did not increase systematically with the introduction of the model-and-praise procedure. Together these findings provide a demonstration of generalized vocal imitation in infants, a population in which it had not previously been shown to occur.