Post-Encoding Semantic Processing Produces Systematic Distortions in Episodic Memory

How new experiences can update a memory has important consequences for its long-term storage, but little is known about how different kinds of re exposure may differentially influence its content. Inspired by theories of memory reconstruction that posit that memory retrieval depends on the integration of idiosyncratic details and relevant general knowledge, we investigated how exposure to a memory through category- or item-level processing may strengthen its episodic and semantic components. Across three behavioral experiments, participants encoded image-location associations in a protocol designed to generate a conflict between memory for specific images and knowledge of the general location of other images from the same category. Following learning of the locations, participants completed manipulations aimed to prioritize category-level or item-level processing of the images. We hypothesized that requiring semantic processing after learning would reinforce prior category knowledge associated with each image and increase category-driven distortions in memory at test. Our findings revealed that memory for images that underwent semantic processing were less precise and more distorted relative to memories that underwent item-level processing and relative to those that were not re-exposed after encoding. Furthermore, post-encoding manipulations more strongly updated memories of atypical category members, suggesting that the organization of prior knowledge can govern the extent that new memories can be updated. Together, these results highlight the active role of post‑encoding manipulations in differentially reshaping memory content and provide compelling evidence that episodic memory retrieval is a constructive process that integrates across prior knowledge, discrete experiences, and subsequent re-exposure.