Repeat after you: Contingent vocal imitation increases children's vocalizations and orienting responses.

Previous research has shown that contingent vocal imitation has a reinforcing effect on vocalizations emitted by children. Nevertheless, the precise contingencies that have a reinforcing effect on vocalizations remain unclear. This study examined the effects of five conditions (contingent vocal imitation, contingent interaction, noncontingent vocal imitation, noncontingent physical touch, and a no-interaction control condition) on the vocalizations emitted by three children with developmental disabilities. We evaluated the effects of these conditions using an alternating-treatments design embedded within a multiple-probe-across-participants design. Contingent vocal imitation led to greater increases in the vocalizations emitted by all three participants than by those in all the other conditions, and the size of this effect was large. We also found increases in orienting responses during the contingent imitation condition and increases in echoic responses postintervention for two of the participants. We discussed implications for practitioners who work with young children with language delays.