scholarly journals Atypically larger variability of resource allocation accounts for visual working memory deficits in schizophrenia

2021 ◽  
Vol 17 (11) ◽  
pp. e1009544
Author(s):  
Yi-Jie Zhao ◽  
Tianye Ma ◽  
Li Zhang ◽  
Xuemei Ran ◽  
Ru-Yuan Zhang ◽  
...  
Keyword(s):  
Working Memory ◽  
Resource Allocation ◽  
Visual Working Memory ◽  
Computational Models ◽  
Alternative View ◽  
Capacity Theory ◽  
Recent Developments ◽  
Healthy Control ◽  
Functional Relevance ◽  
Almost All

Working memory (WM) deficits have been widely documented in schizophrenia (SZ), and almost all existing studies attributed the deficits to decreased capacity as compared to healthy control (HC) subjects. Recent developments in WM research suggest that other components, such as precision, also mediate behavioral performance. It remains unclear how different WM components jointly contribute to deficits in schizophrenia. We measured the performance of 60 SZ (31 females) and 61 HC (29 females) in a classical delay-estimation visual working memory (VWM) task and evaluated several influential computational models proposed in basic science of VWM to disentangle the effect of various memory components. We show that the model assuming variable precision (VP) across items and trials is the best model to explain the performance of both groups. According to the VP model, SZ exhibited abnormally larger variability of allocating memory resources rather than resources or capacity per se. Finally, individual differences in the resource allocation variability predicted variation of symptom severity in PSZ, highlighting its functional relevance to schizophrenic pathology. This finding was further verified using distinct visual features and subject cohorts. These results provide an alternative view instead of the widely accepted decreased-capacity theory and highlight the key role of elevated resource allocation variability in generating atypical VWM behavior in schizophrenia. Our findings also shed new light on the utility of Bayesian observer models to characterize mechanisms of mental deficits in clinical neuroscience.

scholarly journals Atypically larger variability of resource allocation accounts for visual working memory deficits in schizophrenia

2018 ◽  
Author(s):  
Yi-Jie Zhao ◽  
Tianye Ma ◽  
Xuemei Ran ◽  
Li Zhang ◽  
Ru-Yuan Zhang ◽  
...  
Keyword(s):  
Working Memory ◽  
Visual Working Memory ◽  
Computational Models ◽  
Variable Precision ◽  
Capacity Theory ◽  
Healthy Control ◽  
New Perspective ◽  
Almost All ◽  
Memory Precision ◽  
Memory Resources

AbstractSchizophrenia patients are known to have profound deficits in visual working memory (VWM), and almost all previous studies attribute the deficits to decreased memory capacity. This account, however, ignores the potential contributions of other VWM components (e.g., memory precision). Here, we measure the VWM performance of schizophrenia patients and healthy control subjects on two classical delay-estimation tasks. Moreover, we thoroughly evaluate several established computational models of VWM to compare the performance of the two groups. We find that the model assuming variable precision across items and trials is the best model to explain the performance of both groups. According to the variable-precision model, schizophrenia subjects exhibit abnormally larger variability of allocating memory resources rather than resources per se. These results invite a rethink of the widely accepted decreased-capacity theory and propose a new perspective on the diagnosis and rehabilitation of schizophrenia.

T202. Atypically Larger Variability of Resource Allocation Accounts for Visual Working Memory Deficits in Schizophrenia

2019 ◽  
Vol 85 (10) ◽  
pp. S208-S209
Author(s):  
Yijie Zhao ◽  
Xuemei Ran ◽  
Li Zhang ◽  
Ruyuan Zhang ◽  
Yixuan Ku
Keyword(s):  
Working Memory ◽  
Resource Allocation ◽  
Visual Working Memory ◽  
Memory Deficits

scholarly journals Perceptual stimuli with novel bindings interfere with visual working memory

2021 ◽  
Author(s):  
Peter Shepherdson
Keyword(s):  
Working Memory ◽  
Change Detection ◽  
Visual Working Memory ◽  
Computational Models ◽  
Recall Performance ◽  
Visual Interference ◽  
Key Factor ◽  
Subsequent Recall ◽  
New Feature ◽  
Change Response

AbstractWhat influences the extent to which perceptual information interferes with the contents of visual working memory? In two experiments using a combination of change detection and continuous reproduction tasks, I show that binding novelty is a key factor in producing interference. In Experiment 2, participants viewed arrays of colored circles, then completed consecutive change detection and recall tests of their memory for stochastically independent items from the same array. When the probe used in the change detection test was novel (i.e., required a “change” response), subsequent recall performance was worse than in trials with matching (i.e., “no change”) probes, irrespective of whether or not the same item was tested in both phases. In Experiment 2, participants viewed arrays of oriented arrows, then completed a change detection (requiring memory) or direction judgement (not requiring memory) test, followed by recalling a stochastically independent item. Again, novel probes in the first phase led to worse recall, irrespective of whether the initial task required memory. This effect held whether the probe was wholly novel (i.e., a new feature presented at any location) or simply involved a novel binding (i.e., an old feature presented at a new location). These findings highlight the role of novelty in visual interference, consistent with the assumptions of computational models of WM, and suggest that new bindings of old information are sufficient to produce such interference.

scholarly journals Discrete resource allocation in visual working memory.

2009 ◽  
Vol 35 (5) ◽  
pp. 1359-1367 ◽  
Author(s):  
Brian Barton ◽  
Edward F. Ester ◽  
Edward Awh
Keyword(s):  
Working Memory ◽  
Resource Allocation ◽  
Visual Working Memory

scholarly journals Greater visual working memory capacity for visually-matched stimuli when they are recognized as meaningful

2019 ◽  
Author(s):  
Isabel Asp ◽  
Viola S. Störmer ◽  
Timothy F. Brady
Keyword(s):  
Working Memory ◽  
Visual Working Memory ◽  
Memory Performance ◽  
Working Memory Capacity ◽  
Visual Complexity ◽  
Memory Capacity ◽  
Subjective Perception ◽  
Neural Delay ◽  
Almost All ◽  
Fixed Pool

Almost all models of visual working memory assume it has a fixed capacity: some models propose a limit of 3-4 objects, where others propose there is a fixed pool of resources for each basic visual feature. Recent findings, however, suggest that memory performance is improved for real-world objects. What supports these increases in capacity? Here, we test whether the meaningfulness of a stimulus alone influences working memory capacity while controlling for visual complexity and directly assessing the active component of working memory using EEG. Participants remembered ambiguous stimuli that could either be perceived as a face or as meaningless shapes. Participants had higher performance and increased neural delay activity when the memory display consisted of more meaningful stimuli and when they subjectively perceived the stimuli as meaningful. Thus, there are genuine increases in working memory capacity that arise from the subjective perception of the stimulus as meaningful.

scholarly journals Electrophysiological correlates of the flexible allocation of visual working memory resources

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Christine Salahub ◽  
Holly A. Lockhart ◽  
Blaire Dube ◽  
Naseem Al-Aidroos ◽  
Stephen M. Emrich
Keyword(s):  
Working Memory ◽  
Resource Allocation ◽  
Visual Working Memory ◽  
Visual Information ◽  
Memory Load ◽  
Continuous Model ◽  
Attentional Selection ◽  
Distribution Of Resources ◽  
Flexible Resource ◽  
Memory Resources

AbstractVisual working memory is a brief, capacity-limited store of visual information that is involved in a large number of cognitive functions. To guide one’s behavior effectively, one must efficiently allocate these limited memory resources across memory items. Previous research has suggested that items are either stored in memory or completely blocked from memory access. However, recent behavioral work proposes that memory resources can be flexibly split across items based on their level of task importance. Here, we investigated the electrophysiological correlates of flexible resource allocation by manipulating the distribution of resources amongst systematically lateralized memory items. We examined the contralateral delay activity (CDA), a waveform typically associated with the number of items held in memory. Across three experiments, we found that, in addition to memory load, the CDA flexibly tracks memory resource allocation. This allocation occurred as early as attentional selection, as indicated by the N2pc. Additionally, CDA amplitude was better-described when fit with a continuous model predicted by load and resources together than when fit with either alone. Our findings show that electrophysiological markers of attentional selection and memory maintenance not only track memory load, but also the proportion of memory resources those items receive.

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