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Mark Schurgin, Corbin Cunningham, Howard Egeth, Timothy Brady; Episodic Memory Replaces Active Maintenance in Working Memory When Available. Journal of Vision 2018;18(10):187. doi: https://doi.org/10.1167/18.10.187.
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Humans have remarkable episodic long-term memory abilities, capable of storing thousands of objects with significant detail (Shepard, 1967; Standing, 1973; Brady, Konkle, Alvarez, & Oliva, 2008). However, it remains unknown how episodic long-term memory is utilized during the short-term maintenance of information. Specifically, if people have an episodic memory for an item, how does this affect subsequent working memory for that same item? To address this, participants were shown two objects they needed to hold in working memory in order to make a subsequent perceptual discrimination based on one of the two objects. We found that when a participant encounters an object that was previously encoded in episodic memory, they maintain approximately half as much perceptual information actively in working memory as when they were shown two completely new objects (t(19)=2.57, p=0.02) as indexed by the CDA - a well-known neural signature reflecting the active storage of perceptual information (Vogel & Machizawa, 2004). Despite maintaining significantly less information actively in working memory, participants did not demonstrate any differences in behavioral performance (t(19)=0.92, p=0.37). Thus, people can dynamically disengage working memory when episodic memory is available without incurring a cost. However, this does not mean that participants always utilize episodic memory when it is available. In a follow-up experiment we introduced substantial perceptual interference into the working memory task and found that participants actively stored items in working memory even when they had existing episodic memories of those items. These results clarify the conditions under which episodic and working memory operate. Specifically, working memory is engaged when new information is encountered or when perceptual interference is high. Episodic memory is otherwise utilized in lieu of working memory, if available. These data demonstrate the interactions between working memory and episodic memory are much more dynamic and fluid than previously thought.
Meeting abstract presented at VSS 2018
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