scholarly journals Narratives bridge the divide between distant events in episodic memory

Author(s):  
Brendan I. Cohn-Sheehy ◽  
Angelique I. Delarazan ◽  
Jordan E. Crivelli-Decker ◽  
Zachariah M. Reagh ◽  
Nidhi S. Mundada ◽  
...  

AbstractMany studies suggest that information about past experience, or episodic memory, is divided into discrete units called “events.” Yet we can often remember experiences that span multiple events. Events that occur in close succession might simply be linked because of their proximity to one another, but we can also build links between events that occur farther apart in time. Intuitively, some kind of organizing principle should enable temporally distant events to become bridged in memory. We tested the hypothesis that episodic memory exhibits a narrative-level organization, enabling temporally distant events to be better remembered if they form a coherent narrative. Furthermore, we tested whether post-encoding memory consolidation is necessary to integrate temporally distant events. In three experiments, participants learned and subsequently recalled events from fictional stories, in which pairs of temporally distant events involving side characters (“sideplots”) either formed one coherent narrative or two unrelated narratives. Across participants, we varied whether recall was assessed immediately after learning, or after a delay: 24 hours, 12 hours between morning and evening (“wake”), or 12 hours between evening and morning (“sleep”). Participants recalled more information about coherent than unrelated narrative events, in most delay conditions, including immediate recall and wake conditions, suggesting that post-encoding consolidation was not necessary to integrate temporally distant events into a larger narrative. Furthermore, post hoc modeling across experiments suggested that narrative coherence facilitated recall over and above any effects of sentence-level semantic similarity. This reliable memory benefit for coherent narrative events supports theoretical accounts which propose that narratives provide a high-level architecture for episodic memory.

2020 ◽  
Author(s):  
Brendan Cohn-Sheehy ◽  
Angelique Delarazan ◽  
Zachariah Reagh ◽  
Nidhi Mundada ◽  
Andrew P. Yonelinas ◽  
...  

Many studies suggest that information about past experience, or episodic memory, is divided into discrete units called “events.” Paradoxically, we can often remember experiences that span multiple events. Events that occur in close succession might simply be bridged because of their proximity to one another, but many events occur farther apart in time. Intuitively, some kind of organizing principle should enable these temporally-distant events to become bridged in memory. We tested the hypothesis that episodic memory exhibits a narrative-level organization, enabling temporally-distant events to be better remembered if they form a coherent narrative. Furthermore, we tested whether a post-encoding consolidation process is necessary to integrate temporally-distant events. Participants learned and subsequently recalled events from fictional stories, in which pairs of temporally-distant events involving side-characters (“sideplots”) either formed one coherent narrative or two unrelated narratives. In three experiments, participants were cued to recall the stories either immediately, after a 24-hour delay, or after a 12-hour delay which elapsed during daytime (“wake”) versus nighttime (“sleep”). Participants recalled more information about coherent than unrelated narrative events, in most delay conditions, and the delay and sleep manipulations indicated that post-encoding consolidation was not necessary to integrate temporally-distant narrative events. Post-hoc modeling across experiments suggested that sentence-level semantic similarity could not solely account for the coherence benefit. This reliable memory benefit for coherent narrative events supports theoretical accounts which propose that higher-order semantic structures scaffold episodic memory.


2015 ◽  
Vol 74 (2) ◽  
pp. 91-104 ◽  
Author(s):  
Bo Wang

Emotional arousal induced after learning has been shown to modulate memory consolidation. However, it is unclear whether the effect of postlearning arousal can extend to different aspects of memory. This study examined the effect of postlearning positive arousal on both item memory and source memory. Participants learned a list of neutral words and took an immediate memory test. Then they watched a positive or a neutral videoclip and took delayed memory tests after either 25 minutes or 1 week had elapsed after the learning phase. In both delay conditions, positive arousal enhanced consolidation of item memory as measured by overall recognition. Furthermore, positive arousal enhanced consolidation of familiarity but not recollection. However, positive arousal appeared to have no effect on consolidation of source memory. These findings have implications for building theoretical models of the effect of emotional arousal on consolidation of episodic memory and for applying postlearning emotional arousal as a technique of memory intervention.


2021 ◽  
Vol 11 (15) ◽  
pp. 6975
Author(s):  
Tao Zhang ◽  
Lun He ◽  
Xudong Li ◽  
Guoqing Feng

Lipreading aims to recognize sentences being spoken by a talking face. In recent years, the lipreading method has achieved a high level of accuracy on large datasets and made breakthrough progress. However, lipreading is still far from being solved, and existing methods tend to have high error rates on the wild data and have the defects of disappearing training gradient and slow convergence. To overcome these problems, we proposed an efficient end-to-end sentence-level lipreading model, using an encoder based on a 3D convolutional network, ResNet50, Temporal Convolutional Network (TCN), and a CTC objective function as the decoder. More importantly, the proposed architecture incorporates TCN as a feature learner to decode feature. It can partly eliminate the defects of RNN (LSTM, GRU) gradient disappearance and insufficient performance, and this yields notable performance improvement as well as faster convergence. Experiments show that the training and convergence speed are 50% faster than the state-of-the-art method, and improved accuracy by 2.4% on the GRID dataset.


2021 ◽  
Vol 36 (2) ◽  
Author(s):  
Bas van Woerkum

AbstractA persisting question in the philosophy of animal minds is which nonhuman animals share our capacity for episodic memory (EM). Many authors address this question by primarily defining EM, trying to capture its seemingly unconstrained flexibility and independence from environmental and bodily constraints. EM is therefore often opposed to clearly context-bound capacities like tracking environmental regularities and forming associations. The problem is that conceptualizing EM in humans first, and then reconstructing how humans evolved this capacity, provides little constraints for understanding the evolution of memory abilities in other species: it defines “genuine” EM as independent from animals’ evolved sensorimotor setup and learning abilities. In this paper, I define memory in terms of perceptual learning: remembering means “knowing (better) what to do in later situations because of past experience in similar earlier situations”. After that, I explain how episodic memory can likewise be explained in terms of perceptual learning. For this, we should consider that the information in animals’ ecological niches is much richer than has hitherto been presumed. Accordingly, instead of asking “given that environmental stimuli provide insufficient information about the cache, what kind of representation does the jay need?” we ask “given that the animal performs in this way, what kind of information is available in the environment?” My aim is not to give a complete alternative explanation of EM; rather, it is to provide conceptual and methodological tools for more zoocentric comparative EM-research.


2021 ◽  
Vol 11 (4) ◽  
pp. 410
Author(s):  
Simon Ruch ◽  
Kristoffer Fehér ◽  
Stephanie Homan ◽  
Yosuke Morishima ◽  
Sarah Maria Mueller ◽  
...  

Slow-wave sleep (SWS) has been shown to promote long-term consolidation of episodic memories in hippocampo–neocortical networks. Previous research has aimed to modulate cortical sleep slow-waves and spindles to facilitate episodic memory consolidation. Here, we instead aimed to modulate hippocampal activity during slow-wave sleep using transcranial direct current stimulation in 18 healthy humans. A pair-associate episodic memory task was used to evaluate sleep-dependent memory consolidation with face–occupation stimuli. Pre- and post-nap retrieval was assessed as a measure of memory performance. Anodal stimulation with 2 mA was applied bilaterally over the lateral temporal cortex, motivated by its particularly extensive connections to the hippocampus. The participants slept in a magnetic resonance (MR)-simulator during the recordings to test the feasibility for a future MR-study. We used a sham-controlled, double-blind, counterbalanced randomized, within-subject crossover design. We show that stimulation vs. sham significantly increased slow-wave density and the temporal coupling of fast spindles and slow-waves. While retention of episodic memories across sleep was not affected across the entire sample of participants, it was impaired in participants with below-average pre-sleep memory performance. Hence, bi-temporal anodal direct current stimulation applied during sleep enhanced sleep parameters that are typically involved in memory consolidation, but it failed to improve memory consolidation and even tended to impair consolidation in poor learners. These findings suggest that artificially enhancing memory-related sleep parameters to improve memory consolidation can actually backfire in those participants who are in most need of memory improvement.


SLEEP ◽  
2019 ◽  
Vol 42 (Supplement_1) ◽  
pp. A97-A97
Author(s):  
Sanna Lokhandwala ◽  
Jamie Allfisher ◽  
Rebecca M C Spencer

SIMULATION ◽  
1999 ◽  
Vol 73 (5) ◽  
pp. 281-287 ◽  
Author(s):  
Mikel D. Petty ◽  
Piotr S. Windyga

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