Dataset Information

An Episodic Model of Task Switching Effects: Erasing the Homunculus from Memory.

ABSTRACT: The Parallel Episodic Processing (PEP) model is a neural network for simulating human performance in speeded response time tasks. It learns with an exemplar-based memory store and it is capable of modelling findings from various subdomains of cognition. In this paper, we show how the PEP model can be designed to follow instructions (e.g., task rules and goals). The extended PEP model is then used to simulate a number of key findings from the task switching domain. These include the switch cost, task-rule congruency effects, response repetition asymmetries, cue repetition benefits, and the full pattern of means from a recent feature integration decomposition of cued task switching (Schmidt & Liefooghe, 2016). We demonstrate that the PEP model fits the participant data well, that the model does not possess the flexibility to match any pattern of results, and that a number of competing task switching models fail to account for key observations that the PEP model produces naturally. Given the parsimony and unique explanatory power of the episodic account presented here, our results suggest that feature-integration biases have a far greater power in explaining task-switching performance than previously assumed.

SUBMITTER: Schmidt JR

PROVIDER: S-EPMC7485406 | biostudies-literature | 2020 Sep

REPOSITORIES: biostudies-literature

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An Episodic Model of Task Switching Effects: Erasing the Homunculus from Memory.

Schmidt James R JR Liefooghe Baptist B De Houwer Jan J

Journal of cognition 20200910 1

The Parallel Episodic Processing (PEP) model is a neural network for simulating human performance in speeded response time tasks. It learns with an exemplar-based memory store and it is capable of modelling findings from various subdomains of cognition. In this paper, we show how the PEP model can be designed to follow instructions (e.g., task rules and goals). The extended PEP model is then used to simulate a number of key findings from the task switching domain. These include the switch cost, ...[more]

PMID: 32964181

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Project description:Many studies have shown that healthy elderly subjects and patients with Alzheimer's disease (AD) who carry the apolipoprotein E (ApoE) ε4 allele have worse cognitive function and more severe brain atrophy than non-carriers. However, it remains unclear whether this ApoE polymorphism leads to changes of cognition and brain morphology in healthy young adults. In this study, we used an established model to measure verbal episodic memory and core executive function (EF) components (response inhibition, working memory and task switching) in 32 ApoE ε4 carriers and 40 non-carriers between 20 years and 40 years of age. To do this, we carried out an adapted auditory verbal learning test and three computerized EF tasks. High-resolution head magnetic resonance scans were performed in all participants and voxel-based morphometry (VBM) was used for image processing and analysis. Multivariate analysis of variance (ANOVA) performed on memory measures showed that the overall verbal episodic memory of ApoE ε4 carriers was significantly worse than non-carriers (Wilk's λ = 4.884, P = 0.004). No significant differences were detected in overall EF between the two groups. Post hoc analyses revealed group differences in terms of immediate recall, recognition and task switching, which favored non-carriers. VBM analysis showed gray matter (GM) bilateral reductions in the medial and dorsolateral frontal, parietal and left temporal cortices in the carrier group relative to the non-carrier group, which were most significant in the bilateral anterior and middle cingulate gyri. However, these changes in GM volume were not directly associated with changes in cognitive function. Our data show that the ApoE ε4 allele is associated with poorer performance in verbal episodic memory and task switching, and a reduction in GM volume in healthy young adults, suggesting that the effects of ApoE ε4 upon cognition and brain morphology exist long before the possible occurrence of AD.

Dataset Information

An Episodic Model of Task Switching Effects: Erasing the Homunculus from Memory.

Publications

An Episodic Model of Task Switching Effects: Erasing the Homunculus from Memory.

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