The effect of multiple reminders on long-term retention in human infants

The present series of experiments compared the effects of single- and multiple-reminder procedures on the long-term memory of 3-month-old human infants. Subjects were trained in the mobile conjugate reinforcement paradigm, and the reminder treatment was a brief, noncontingent exposure to the moving mobile. In Experiment 1, independent groups received one or two reminder treatments during the 3 weeks following the conclusion of training. Independent groups were tested 1, 3, 7, 14, or 22 days following the last (or only) reminder (i.e., 21-42 days after the end of training). Although retention was equivalent 1 day after one or two reminder treatments, subsequent retention was significantly prolonged by the second reminder treatment: infants receiving a single reminder treatment demonstrated no evidence of retention 7 days after the reminder, but infants receiving two reminder treatments demonstrated perfect retention as long as 14 days later. In Experiment 2, retention was observed 14 days after two reminder treatments irrespective of whether the treatments were presented during the first and second or the third and fourth weeks following the conclusion of training. In Experiment 3, the effect of three reminder treatments on retention was examined. Although retention was excellent when infants were tested 1 day after the third reminder, retention after longer intervals was no better than that observed after a single reminder treatment.