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48
Domaingeneral mechanisms of complex working memory span
- Neuroimage
, 2011
"... A new fMRI complex working memory span paradigm was used to identify brain regions making domaingeneral contributions to working memory task performance. For both verbal and spatial versions of the task, complex working memory span performance increased the activity in lateral prefrontal, anterior ..."
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A new fMRI complex working memory span paradigm was used to identify brain regions making domaingeneral contributions to working memory task performance. For both verbal and spatial versions of the task, complex working memory span performance increased the activity in lateral prefrontal, anterior cingulate, and parietal cortices during the Encoding, Maintenance, and Coordination phase of task performance. Meanwhile, overlapping activity in anterior prefrontal and medial temporal lobe regions was associated with both verbal and spatial recall from working memory. These findings help to adjudicate several contested issues regarding the executive mechanisms of working memory, the separability of short-term and working memory in the verbal and spatial domains, and the relative contribution of short-term and long-term memory mechanisms to working memory capacity. The study also provides a vital bridge between psychometric and neuroimaging approaches to working memory, and constrains our understanding of how working memory may contribute to the broader landscape of cognitive performance.
Research strategy in the study of memory: Fads, fallacies, and the search for the “coordinates of truth
- Perspectives on Psychological Science
, 2011
"... This article presents an evaluation of research strategy in the psychology of memory. To the extent that a strategy can be discerned, it appears less than optimal in several respects. It relates only weakly to subjective experience, it does not clearly differentiate between structure and strategy, a ..."
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This article presents an evaluation of research strategy in the psychology of memory. To the extent that a strategy can be discerned, it appears less than optimal in several respects. It relates only weakly to subjective experience, it does not clearly differentiate between structure and strategy, and it is oriented more toward remembering which words were in a list than to the diverse functions that memory serves. This last limitation fosters assumptions about memory that are false: that encoding and retrieval are distinct modes of operation; that the effects of repetition, duration, and recency are interchangeable; and that memory is ahistorical. Theories that parsimoniously explain data from single tasks will never generalize to memory as a whole because their core assumptions are too limited. Instead, memory theory should be based on a broad variety of evidence. Using findings from several memory tasks and observations of everyday memory, I suggest some ways in which involuntary reminding plays a central role in cognition. The evolutionary purpose of memory may have been the construction and maintenance—through reminding—of a spatio-temporal model of the environment. I conclude by recommending ways in which efficiency of the field’s research strategy might be improved. Keywords reminding, memory judgments, memory, parsimony Everyone has heard the East Indian fable of the blind philoso-
Human memory reconsolidation can be explained using the temporal context model
- Psychonomic Bulletin & Review
, 2011
"... 2009) suggests that episodic memory for a previously studied list can be updated to include new items, if participants are reminded of the earlier list just prior to learning a new list. The key finding from the Hupbach studies was an asymmetric pattern of intrusions, whereby participants intruded n ..."
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2009) suggests that episodic memory for a previously studied list can be updated to include new items, if participants are reminded of the earlier list just prior to learning a new list. The key finding from the Hupbach studies was an asymmetric pattern of intrusions, whereby participants intruded numerous items from the second list when trying to recall the first list, but not viceversa. Hupbach et al. (2007; 2009) explained this pattern in terms of a cellular reconsolidation process, whereby first-list memory is rendered labile by the reminder and the labile memory is then updated to include items from the second list. Here, we show that the temporal context model of memory, which lacks a cellular reconsolidation process, can account for the asymmetric intrusion effect, using well-established principles of contextual reinstatement and item– context binding.
Semantic cuing and the scale insensitivity of recency and contiguity
, 2011
"... In recalling a set of previously experienced events, people exhibit striking effects of recency, contiguity, and similarity: Recent items tend to be recalled best and first, and items that were studied in neighboring positions or that are similar to one another in some other way tend to evoke one an ..."
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In recalling a set of previously experienced events, people exhibit striking effects of recency, contiguity, and similarity: Recent items tend to be recalled best and first, and items that were studied in neighboring positions or that are similar to one another in some other way tend to evoke one another during recall. Effects of recency and contiguity have most often been investigated in tasks that require people to recall random word lists. Similarity effects have most often been studied in tasks that require people to recall categorized word lists. Here we examine recency and contiguity effects in lists composed of items drawn from 3 distinct taxonomic categories and in which items from a given category are temporally separated from one another by items from other categories, all of which are tested for recall. We find evidence for long-term recency and for long-range contiguity, bolstering support for temporally sensitive models of memory and highlighting the importance of understanding the interaction between temporal and semantic information during memory search.
Optimizing design efficiency of free recall events for fMRI
- J Cogn Neurosci
, 2010
"... ■ Free recall is a fundamental paradigm for studyingmemory re-trieval in the context of minimal cue support. Accordingly, free recall has been extensively studied using behavioral methods. However, the neural mechanisms that support free recall have not been fully investigated due to technical chall ..."
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■ Free recall is a fundamental paradigm for studyingmemory re-trieval in the context of minimal cue support. Accordingly, free recall has been extensively studied using behavioral methods. However, the neural mechanisms that support free recall have not been fully investigated due to technical challenges associated with probing individual recall events with neuroimagingmethods. Of particular concern is the extent to which the uncontrolled latencies associated with recall events can confer sufficient design efficiency topermit neural activation for individual conditions tobe distinguished. The present study sought to rigorously assess the feasibility of testing individual free recall events with fMRI.Weused both theoretically and empirically derived free recall latency distri-butions to generate simulated fMRI data sets and assessed design efficiency across a range of parameters that describe free recall per-formance and fMRI designs. In addition, two fMRI experiments em-pirically assessed whether differential neural activation in visual cortex at onsets determined by true free recall performance across different conditions can be resolved. Collectively, these results specify the design and performance parameters that can provide comparable efficiency between free recall designs and more tradi-tional jittered event-related designs. These findings suggest that as-sessing BOLD response during free recall using fMRI is feasible, under certain conditions, and can serve as a powerful tool in under-standing the neural bases of memory search and overt retrieval. ■
Dissociable networks involved in spatial and temporal order source retrieval
- Neuroimage
, 2011
"... Space and time are important components of our episodic memories. Without this information, we cannot determine the "where and when" of our recent memories, rendering it difficult to disambiguate individual episodes from each other. The neural underpinnings of spatial and temporal order m ..."
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Space and time are important components of our episodic memories. Without this information, we cannot determine the "where and when" of our recent memories, rendering it difficult to disambiguate individual episodes from each other. The neural underpinnings of spatial and temporal order memory in humans remain unclear, in part because of difficulties in disentangling the contributions of these two types of source information. To address this issue, we conducted an experiment in which participants first navigated a virtual city, experiencing unique routes in a specific temporal order and learning about the spatial layout of the city. Spatial and temporal order information were dissociated in our task such that learning one type of information did not facilitate the other behaviorally. This allowed us to then address the extent to which the two types of information involved functionally distinct or overlapping brain areas. During functional magnetic resonance imaging (fMRI), participants retrieved information about the relative distance of stores within the city (spatial task) and the temporal order of stores from each other (temporal task). Comparable hippocampal activity was observed during these two tasks, but greater prefrontal activity was seen during temporal order retrieval whereas greater parahippocampal activity was seen during spatial retrieval. We suggest that while the brain possesses dissociable networks for maintaining and representing spatial layout and temporal order components of episodic memory, this information may converge into a common representation for source memory in areas such as the hippocampus.
Competition and Cooperation Among Similar Representations: Toward a Unified Account of Facilitative and Inhibitory Effects of Lexical Neighbors
"... One of the core principles of how the mind works is the graded, parallel activation of multiple related or similar representations. Parallel activation of multiple representations has been particularly important in the development of theories and models of language processing, where coactivated repr ..."
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One of the core principles of how the mind works is the graded, parallel activation of multiple related or similar representations. Parallel activation of multiple representations has been particularly important in the development of theories and models of language processing, where coactivated representations (neighbors) have been shown to exhibit both facilitative and inhibitory effects on word recognition and production. Researchers generally ascribe these effects to interactive activation and competition, but there is no unified explanation for why the effects are facilitative in some cases and inhibitory in others. We present a series of simulations of a simple domain-general interactive activation and competition model that is broadly consistent with more specialized domain-specific models of lexical processing. The results showed that interactive activation and competition can indeed account for the complex pattern of reversals. Critically, the simulations revealed a core computational principle that determines whether neighbor effects are facilitative or inhibitory: Strongly active neighbors exert a net inhibitory effect, and weakly active neighbors exert a net facilitative effect.
A Bayesian Analysis of Dynamics in Free Recall
"... We develop a probabilistic model of human memory performance in free recall experiments. In these experiments, a subject first studies a list of words and then tries to recall them. To model these data, we draw on both previous psychological research and statistical topic models of text documents. W ..."
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We develop a probabilistic model of human memory performance in free recall experiments. In these experiments, a subject first studies a list of words and then tries to recall them. To model these data, we draw on both previous psychological research and statistical topic models of text documents. We assume that memories are formed by assimilating the semantic meaning of studied words (represented as a distribution over topics) into a slowly changing latent context (represented in the same space). During recall, this context is reinstated and used as a cue for retrieving studied words. By conceptualizing memory retrieval as a dynamic latent variable model, we are able to use Bayesian inference to represent uncertainty and reason about the cognitive processes underlying memory. We present a particle filter algorithm for performing approximate posterior inference, and evaluate our model on the prediction of recalled words in experimental data. By specifying the model hierarchically, we are also able to capture inter-subject variability. 1
Forgetting the Words but Remembering the Meaning: Modeling Forgetting in a Verbal and Semantic Tag Recommender
"... Abstract. We assume that recommender systems are more successful, when they are based on a thorough understanding of how people process information. In the current paper we test this assumption in the context of social tagging systems. Cognitive research on how people assign tags has shown that they ..."
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Abstract. We assume that recommender systems are more successful, when they are based on a thorough understanding of how people process information. In the current paper we test this assumption in the context of social tagging systems. Cognitive research on how people assign tags has shown that they draw on two interconnected levels of knowledge in their memory: on a conceptual level of semantic fields or LDA topics, and on a lexical level that turns patterns on the semantic level into words. Another strand of tagging research reveals a strong impact of time-dependent forgetting on users ’ tag choices, such that recently used tags have a higher probability being reused than “older ” tags. In this paper, we align both strands by implementing a computational theory of human memory that integrates the two-level conception and the process of forgetting in form of a tag recommender. Furthermore, we test the approach in three large-scale social tagging datasets that are drawn from BibSonomy, CiteULike and Flickr.
