PT  - JOURNAL ARTICLE
AU  - Schurgin, Mark W.
AU  - Cunningham, Corbin A.
AU  - Egeth, Howard E.
AU  - Brady, Timothy F.
TI  - Episodic Memory Can Replace Active Storage in Visual Working Memory
AID  - 10.1101/381848
DP  - 2018 Jan 01
TA  - bioRxiv
PG  - 381848
4099  - http://biorxiv.org/content/early/2018/08/01/381848.short
4100  - http://biorxiv.org/content/early/2018/08/01/381848.full
AB  - Humans have remarkable episodic long-term memory abilities, capable of storing thousands of objects with significant detail. However, it remains unknown how such episodic 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? Here, we demonstrate that under these conditions people can quickly and accurately make use of episodic memory and therefore maintain less information in working memory. We assessed how much information is maintained in working memory by measuring neural activity during the delay period of a working memory task using electroencephalography. We find that despite maintaining less information in working memory when episodic memory representations are available, there is no decrement in memory performance. This suggests people can dynamically disengage working memory and instead use episodic memory when episodic memory is available. However, this does not mean that participants always utilize episodic memory when it is available. In a follow-up experiment, we introduced additional perceptual interference into working memory and found 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 perceptual interference is high. Episodic memory is otherwise rapidly accessed and utilized in lieu of working memory. These data demonstrate the interactions between working memory and episodic memory are more dynamic and fluid than previously thought.Significance Statement Exploring the interaction between working memory and long-term memory is critical to understanding how people make use of memory in everyday tasks. Surprisingly, it remains unknown how having an existing long-term memory affects performance when you need to later remember the same item in a short-term memory task. Using behavioral and electrophysiology methods, we discover that under certain conditions long-term memories can ‘replace’ working memory representations, eliminating the need to hold items in working memory. These results not only elucidate the conditions under which working and long-term memory operate, but also suggest that under the realistic scenario of working with previously encountered items, our memory systems use existing long-term memories to free up working memory resources for use elsewhere.