0061 Background Context but not Sleep Facilitates Visual Episodic Memory for Objects

Abstract

Abstract Introduction Context serves as a retrieval aid and supports accurate recollection of elements within an episodic event. Associative links between elements of the episode can be weakened via decontextualization. Memory traces are considered to be decontextualized when they have undergone a process that makes them less context-dependent and more gist-like. Furthermore, sleep has been shown to facilitate consolidation of newly formed verbal memories, particularly when sleep occurs shortly after learning. The current study sought to better understand what supports accurate retrieval of visual episodic memories and whether they are modulated by sleep. We examined changes in memory accuracy following either a daytime nap or an equivalent period of quiet wakefulness when background context was changed or reinstated at retrieval. Methods Participants were presented with target objects that either appeared in the same scene across multiple trials or in changing scenes during encoding. Memory for target objects was tested using a two-alternative-forced-choice task before and after a 90-min daytime nap (or equivalent period of quiet wakefulness). During testing, the targets either appeared in the same scene context or in a new scene. Results Preliminary behavioural results suggest that recognition accuracy significantly decreased from Test 1 to Test 2. However, there was no difference in recognition scores after a nap compared to a period of quite wakefulness. Recognition was highest, at both tests, when the encoding context was reinstated. There was no difference in recognition between when the context was continually changing and when there was one context change between study and test. Conclusion When it comes to visual episodic memory, context plays a predominant role in accurate retrieval of the elements within the scene. The present results suggest that reinforcing the target object with consistent reinstatement of background context facilitates accurate object retrieval. Context reinstatement strengthened the object-to-scene binding, improving recognition accuracy. This effect remains robust regardless of whether learning was followed by a period of sleep or quite wakefulness, suggesting that context rather than consolidation during sleep plays a key role in visual episodic memory retrieval. Support (if any)