Deferred imitation by 6- and 9-month-old infants: more evidence for declarative memory.

Deferred imitation has recently surfaced as a hallmark measure of nonverbal declarative memory. In two experiments, we examined the developmental origins of deferred imitation during early infancy. Six- and 9-month-old human infants observed an experimenter perform specific actions with multiple objects. The infants' ability to reproduce those actions was assessed following a 24-hr delay. With a single demonstration session, infants of both ages reproduced significantly more actions that had been demonstrated than control actions that had not. These findings challenge the view that memory development is characterized by the emergence of a fundamentally different, declarative memory system later in development. We conclude that the rudiments of declarative memory are present by at least 6 months of age. Copyright 1999 John Wiley & Sons, Inc.