Updating reactivated memories in infancy: II. Time passage and repetition effects

Previous attempts to modify a reactivated memory by passively exposing infants to a novel cue immediately after reactivation were unsuccessful. Presently, we examined other conditions in which passive exposure to a novel cue immediately after reactivation might modify the memory. In three experiments, sixty-two 3-month-olds learned to move a distinctive mobile by kicking, forgot the training memory, and then received a reminder that reactivated it. Immediately afterward, they were passively exposed to a novel mobile. We found that passive exposure to novel information could modify reactivated memories that were older or had been reactivated before. Although exposure to a novel mobile occasionally produced only retroactive interference, memory modification never occurred alone, suggesting that response suppression to the original cue is prerequisite for the modification of reactivated memories. We propose that memory distortion (modification) is not an anomaly but is an adaptive, updating mechanism that ensures that behavior will be guided by memories containing contemporaneous information.