Reinstatement effects on retention at 3 months of age

In three experiments with 56 3-month-olds, we examined different numbers of reinstatements (reminders) on long-term retention. Infants learned to move a crib mobile by kicking and subsequently received one, two, or three rein statements. Each reinstatement was a partial training episode one-sixth the duration of original training. Presenting a single reinstatement when the memory was inactive failed to recover it I day later (Experiment 1), but in creasing the number of reinstatements when the memory was active to two (Ex periment 2) and three (Experiment 3) progressively protracted retention. Al though 3-month-olds typically remember for less than 6 days, after three re instatements they still exhibited retention 6 weeks after training. Untrain ed controls who received an identical regimen of reinstatements exhibited n o retention. These results demonstrate that periodic reinstatements can mai ntain young infants' retention over long delays and that the state of the m emory at the time of reinstatement is critical to its effectiveness. (C) 19 99 Academic Press.