It is widely known that COVID-19 has a number of prolonged effects on general health, wellbeing, and cognitive functioning. However, studies using differentiated performance measures of cognitive functions are still not widely spread making it hard to assess the exact functions that get impaired. Taking into account the similarities between post-COVID ‘brain fog’ and chemofog, we hypothesized that executive functions (EF) would be impaired. Literature search yielded six studies with 14 effect sizes of interest; pooled effect size was small to medium ( ). Combined with a narrative synthesis of six studies without a comparison group, these results show that EF get impaired after COVID-19; although, in most cases the impairment is transient and does not seem to be severe. These results specify the picture of ‘brain fog’ and may help to discover its mechanisms and ways of helping people with long COVID.

An experiment in the dual-task paradigm was carried out to explore the nature of domain-specific and domain-general resource distribution in working memory. The subjects (N = 32) performed symmetry span and letter reading span tasks under visuospatial (tapping) and verbal (articulatory suppression) cognitive load. The effects of task type and cognitive load modality were analyzed. The results are described within the concentric model framework: significant distinctions in relative accuracy under visuospatial and verbal cognitive load in visuospatial and verbal tasks were observed when N elements in the set exceeded the region of direct access capacity, while no such effect was observed for 2–3 element sets. This is attributed to domain-general resources in the region of direct access, and domain-specific resources in the activated long-term memory. We also found evidence for the asymmetric distribution of visuospatial and verbal working memory resources in that the verbal component is more susceptible to cognitive load.

This article provides an analysis of structural changes in second-language (L2)-based semantic memory networks-graphs composed of L2 words as nodes and semantic relations between them as edges, during L2 learning. We used snowball sampling paradigm to create individual semantic networks of participants divided into two groups differing in L2 learning time and then compare their structural characteristics cross-sectionally. The results showed that as L2 learning progresses, semantic memory networks tend to become more connected (by increasing the average node degree), more efficient (by decreasing the average shortest path length), less fragmented (by decreasing the modularity), less centralized (by decreasing the centralization), less dense (by decreasing the density), and no more "small-worlded" (by similar average clustering coefficients and small-world indices). The findings provide quantitative evidence of how the duration of L2 learning shapes the structure of L2-based semantic memory networks generated in the snowball sampling paradigm. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Context and relevance. This article is devoted to identifying structural changes that occur in human semantic memory (SM) when learning a foreign language (FL). This topic has been repeatedly addressed by researchers, but until now it has been studied exclusively within the framework of the “verbal fluency” paradigm, the application of which has shown contradictory results. In order to solve this problem, we conducted a study on English-language material using the “snowball sampling” method, which allows us to present the structure of the SM as a network built on free associations. Objective. The study`s aim is to determine the characteristics of structural changes in SM during the study of FL. Hypothesis. In the course of studying the FL, the network structure of the SM changes towards increasing size, flexibility, connectivity, greater conformity with the “small world” structure and less separation. Methods and materials. The present study involved two groups of linguistic students: the first consisted of first-years (N = 27; gender: 15 f., 12 m.; age: M = 18.14), and the second consisted of fourth-years (N = 29; gender: 18 f., 11 m.; age: M = 21.44). The participants completed a “snowball sampling” task. Based on the results of the task, a network structure of the SM was constructed for each participant, and an intergroup comparison of its parameters was carried out. Results. The results showed that when learning a FL, the SM networks become larger in size (due to an increase in the number of nodes and edges), more connected (due to an increase in the average node degree), more flexible (due to a decrease in the shortest path length), less separated (due to a decrease in modularity), but do not differ in the “small world” index. Conclusions. The features of the changes in SM structure when learning a foreign language are shown. The results emphasize the role of the SM in the development of language abilities in foreign language learners.