During the past decade, a large body of research has shown that memory traces can become labile upon retrieval and must be restabilized. Critically, interrupting this reconsolidation process can abolish a previously stable memory. Although a large number of studies have demonstrated this reconsolidation associated amnesia in nonhuman animals, the evidence for its occurrence in humans is far less compelling, especially with regard to declarative memory. In fact, reactivating a declarative memory often makes it more robust and less susceptible to subsequent disruptions. Here we show that existing declarative memories can be selectively impaired by using a noninvasive retrieval-relearning technique. In six experiments, we show that this reconsolidation-associated amnesia can be achieved 48 h after formation of the original memory, but only if relearning occurred soon after retrieval. Furthermore, the amnesic effect persists for at least 24 h, cannot be attributed solely to source confusion and is attainable only when relearning targets specific existing memories for impairment. These results demonstrate that human declarative memory can be selectively rewritten during reconsolidation.forgetting | human memory | misinformation effect | testing effect | eyewitness memory T he entrenched view that memory becomes permanent upon consolidation has faced considerable scrutiny based on recent works demonstrating that retrieval can destabilize existing memories, and that the reactivated memories need to be reconsolidated (1, 2). During the past decade, a growing body of evidence has revealed the chemical and molecular nature of reconsolidation and its behavioral consequences (3). Critically, when a consolidated memory (e.g., a conditioned fear response) is retrieved, it becomes labile and requires protein synthesis for restabilization, and later retrieval of that memory can be severely impaired if an amnesic treatment is administered during the reconsolidation process.Despite the proliferation of research on reconsolidation, few studies have involved human subjects, perhaps because most pharmacological consolidation blockers are unsuitable for human use (3, 4). When reconsolidation associated memory impairments are demonstrated in humans, the effects have been limited to fear conditioning (5-8), motor sequence learning (9), and drug-induced craving (10). To date, we are aware of no study that has shown reconsolidation-associated impairment in declarative memory. Indeed, even when oral administration of propranolol (a systemic pharmacological consolidation blocker approved for human use) reduced the emotional response associated with a fear-inducing experience (6, 7), it left the declarative recollection intact.* Although several studies have examined whether existing declarative memories can be impaired by interference upon reactivation, none has shown memory impairments similar to those regularly exhibited in fear conditioning. Moreover, these studies used a reminder to trigger reactivation of the original memory while pro...