Persistence and plasticity in the human memory system: An empirical investigation of the overwriting hypothesis
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Description: The human memory system must resolve a critical tension, ensuring that knowledge endures over time (persistence), whilst simultaneously retaining a capacity for updating when knowledge is outdated or erroneous (plasticity). In this thesis, I examine the provocative idea that memory traces can be overwritten with new information, especially during transient periods of retrieval-induced plasticity that occur when a trace undergoes reconsolidation. A systematic review of human reconsolidation studies finds that the evidentiary support for this claim is remarkably tenuous. Furthermore, the theory fails to survive several strong empirical tests. In Experiments 1-7, I do not replicate a previous finding that is widely cited as a convincing demonstration of human reconsolidation. In Experiments 8-10, I revisit the ‘destructive updating’ account of the classic ‘misinformation effect’ in the context of reconsolidation theory. These experiments show that the effect can be eliminated when an appropriate recognition test is used, demonstrating that event traces are not irrecoverably lost, and therefore cannot have been overwritten during reconsolidation. In Experiment 11, I examine whether prior retrieval will help or hinder the correction of naturally occurring semantic misconceptions. Contrary to reconsolidation theory, I find that knowledge updating is not contingent on memory retrieval, nor does it result in the overwriting of prior knowledge.Finally, in the context of media ‘breaking news’ reports (Experiment 12), I find that the provision of an explicit retraction message, coupled with an alternative account with high causal coverage, is insufficient to eliminate reliance on false information. Finally, I contend that the widespread proliferation of ad hoc hypotheses, and the absence of systematic direct replication, has caused the field of reconsolidation to descend into a theoretical quagmire.I make several recommendations based on the principles of open science that may help to restore mechanisms of self-correction and foster genuine theoretical progress.