The Effects of Overtraining on Updating of Human Episodic Memory

Recent research has demonstrated that previously consolidated episodic memories reenter a labile state after being reactivated by contextual cues, making them susceptible to updating through reconsolidation (Hupbach et al. 2007; Hupbach et al. 2008). However, little is known about boundary conditions that limit reconsolidation in humans. The current study uses the list-learning paradigm established by Hupbach et al. to investigate the boundary of memory strength at 96 hour and 5 week time delays. Participants were overtrained on the initial object set, after which they returned for reactivation (or no reactivation) and learned a second object set. During the third session participants were asked to recall only one of the sets. Updating was assessed by measuring levels of intrusions from the alternate set into the memory of the correct set. Overtrained participants showed similar intrusion patterns to normally-trained participants despite increased correct recall, suggesting updating at 96 hours and no updating at 5 weeks. Implications of the results are discussed, including comparisons to recent animal neuroscience research