Reactivation of infant memory

Three-month-old infants learned to activate a crib mobile by means of operant footkicks. Retention of the conditioned response was assessed during a cued recall test with the nonmoving mobile. Although forgetting is typically complete after an 8-day retention interval, infants who received a reactivation treatment--a brief exposure to the reinforcer 24 hours before retention testing--showed no forgetting after retention intervals of either 2 or 4 weeks. Further, the forgetting function after a reactivation treatment did not differ from the original forgetting function. These experiments demonstrate that (i) "reactivation" or "reinstatement" is an effective mechanism by which early experiences can continue to influence behavior over lengthy intervals and (ii) memory deficits in young infants are best viewed as retrieval deficits.