Memory retrieval: a time-locked process in infancy

Three-month-old infants learned to activate an overhead crib mobile by operant footkicking and received a visual reminder of the event (a "reactivation treatment") 2 weeks later, after forgetting had occurred. Subsequent manifestation of the association was a monotonic increasing function of time since the reactivation treatment, and performance of infants tested 8 hours after the remainder was related to the time spent sleeping in the interim (r = 0.75). These data demonstrate that normal retrieval is time-dependent. Moreover, individual data suggest that retrieval may be continuous rather than discontinuous.