Matching behavior in the young infant.

Infants as young as 2--6 weeks have been reported to exhibit matching behavior in response to seeing an adult model tongue protrusion and certain other acts. Matching behavior to the tongue model declines by 12 weeks. The present study was designed to investigate whether (1) this matching behavior represents selective imitation or a released response that can be elicited by a broad but delimited class of incentive stimuli and (2) stimulation of tongue protrusion enhances the response and delays its decline. 24 infants were observed at 6, 10, and 14 weeks. A moving pen and ball were as effective as the tongue model in eliciting tongue protrusion at 6 weeks, while a dangling ring elicited as much hand opening and closing as the hand model at 14 weeks. After the 6-week visit, 12 of the infants were exposed to the tongue model daily. This intervention delayed the decline of matching behavior to the tongue model at 14 weeks. Also, experimental infants responded selectively to the tongue model, while the pen continued to be an effective releaser of tongue protrusions among controls.