Reactivation, interference, and reconsolidation: are recent and remote memories likewise susceptible?

The retrieval of a consolidated, apparently stable memory can return it to a labile state, necessitating another period of stabilization, termed reconsolidation. During reconsolidation, memories are susceptible to modifications, thus providing the opportunity to change unwanted memories. In a test of whether the possibility to alter retrieved memories depends on the age of the memories, participants learned a set of emotional and neutral pictures and recalled it 1, 7, or 28 days later. Immediately after retrieval, participants learned a second set of pictures. Memory retrieval per se enhanced 28-day-old memories but had no effect on 1-day- or 7-day-old memories. Learning new pictures interfered with 1-day-old and 28-day-old memories but not with 7-day-old memories. Evidence for reconsolidation effects was generally rather weak and at most present for 7-day-old memories. These findings show that retrieval and interference have opposite effects on memory that depend on the remoteness of the memories and raise the question under which conditions reconsolidation effects occur in human memory.