Content reinstatement and source confidence during episodic memory retrieval
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Episodic retrieval is the process of bringing information about a past experience from memory into conscious awareness. Variation in the retrieval process, in regard to content and quality of the information retrieved, is believed to rely on the reactivation of neural patterns of activity elicited during the original experience � a process called neural reinstatement. Research in support of this idea has relied on participant reports of retrieval quality, but not content, to assess variation in retrieval. Without measuring the content of retrieval, it is unclear whether reinstatement underlies retrieval per se, or merely the evaluation of retrieval quality. The current study addressed this issue by examining the relationship between the magnitude of neural reinstatement during retrieval, and a direct behavioral measure of both retrieval content and quality. Participants viewed a series of words in the context of three encoding tasks, and then completed a memory test on a series of words in which they first identified the encoding task completed for a given word, and next rated their confidence in that decision. Pattern classification analyses were performed on fMRI data acquired during encoding and retrieval phases to index reinstatement, and reinstatement effects were examined according to the behavioral and neural correlates of source confidence. The findings support a relationship between reinstatement and variation in the content and quality of retrieval, and also suggest a role for regions such as left posterior parietal cortex in monitoring reinstated activity to guide decisions about retrieval quality.