The influence of categorical organization on verbal working memory

Effects of semantic relationship and preactivation on memory updating

Semantic relationship modulates working memory (WM) processes by promoting recall but impairing recognition. Updating is a core mechanism of WM responsible for its stability and flexibility; it allows maintenance of relevant information while removing no-longer relevant one. To our knowledge, no studies specifically investigated how WM updating may benefit from the processing of semantically related material. In the current study, two experiments were run with this aim. In Experiment 1, we found an advantage for semantically related words (vs. unrelated) regardless of their association type (i.e., taxonomic or thematic). A second experiment was run boosting semantic association through preactivation. Findings replicated those of Experiment 1 suggesting that preactivation was effective and improved semantic superiority. In sum, we demonstrated that long-term semantic associations benefitted the updating process, or more generally, overall WM function. In addition, pre-activating semantic nodes of a given word appears likely a process supporting WM and updating; thus, this may be the mechanism favoring word process and memorization in a semantically related text.

Semantic memory and reading comprehension: the relationship through adulthood and aging

Literature shows a relationship between working memory and reading comprehension during lifespan and aging. In addition, a difference between genres of text was shown: the expository text affects the already limited cognitive resources of the older adults, whereas narrative text comprehension seems to be preserved. Undoubtedly, also semantic knowledge plays a key role in reading comprehension; though, and to our knowledge, there are no studies clearly showing the relation between semantic knowledge and reading comprehension in aging. In the current study, we administered to younger adults and older adults a semantic working memory task, two word-span tasks and two reading comprehension tests (narrative and expository genre) to investigate the role of semantic knowledge during comprehension. In line with previous findings, we found that younger adults used flexibly either taxonomic or thematic knowledge, whereas the older adults mainly used thematic knowledge (better preserved from age-related decline). Originally, we found that in younger adults, thematic knowledge accounted for narrative text comprehension, whereas backward span performance accounted for expository text comprehension. On the contrary, in older adults no specific predictors were found for narrative text comprehension, whereas both thematic knowledge and education level were significant predictors of expository text comprehension. Results were discussed in the light of the possible protective role of some factors such as education level and mostly, as an instance of cognitive reserve exemplified by use of thematic knowledge as a residual ability.

Sensitivity detection in memory recognition: interference control as index of taxonomic memory development?

We investigated how long-term memory modulates recognition accuracy performance in typically developing primary school children (aged 7 vs. 9 years). We devised a verbal working memory task where words associations were manipulated to obtain different types of semantic associations (i.e., taxonomic, thematic). Sensitivity detection measures were operationalised as difference between hits and false alarms (for both internal and external intrusions). As our main result, we found sensitivity detection for taxonomic associations was greater in older children than younger. In turn, this showed that taxonomies produce more interference in younger children, and thus, they are not able to take advantage from taxonomic associations, as older children do. These results are helpful in sketching a developmental trend of how semantic memory impacts recognition processes in memory.

[Formula: see text] Developmental dyslexia: How taxonomic and thematic organization affect working memory recall

Semantic long-term memory (LTM) representations can be distinguished in two main classes: taxonomic (i.e., abstract) and thematic (i.e., concrete, experiential). In typically developing children, taxonomies are usually acquired after thematic representations. In the current study, we investigated how LTM semantic representations modulate working memory (WM) recall in children with developmental dyslexia (DD). A sample of children with DD from primary and secondary school paired with a control group for age, gender, schooling, and IQ was administered a semantic WM (SWM) dual task. Here, children had to listen to groups of lists composed of words semantically related (taxonomic, e.g., shop- drugstore-coffee; or thematic, e.g., light-heat-fire) or arbitrarily related, and afterward to recall the last words among each group. Both taxonomic and thematic organizations supported recall in the two groups of children. More specifically, data showed that in typically developing children the taxonomic organization boosted WM recall (vs. the thematic one). On the contrary, in children with DD, the taxonomic organization did not better support recall and yielded effects similar to thematic organization. In children with DD, abstract taxonomic knowledge seems to be less frequently used than thematic knowledge. Findings contribute to sketch memory functioning across different memory systems in DD.

Long-term memory effects on working memory updating development

Long-term memory (LTM) associations appear as important to cognition as single memory contents. Previous studies on updating development have focused on cognitive processes and components, whereas our investigation examines how contents, associated with different LTM strength (strong or weak), might be differentially updated at different ages. To this end, we manipulated association strength of information given at encoding, in order to focus on updating pre-existing LTM associations; specifically, associations for letters. In particular, we controlled for letters usage frequency at the sub-lexical level. We used a task where we dissociated inhibition online (i.e., RTs for updating and controlling inhibition from the same set) and offline (i.e., RTs for controlling inhibition from previously updated sets). Mixed-effect analyses were conducted and showed a substantial behavioural cost when strong associations had to be dismantled online (i.e., longer RTs), compared to weak ones; here, in primary school age children. Interestingly, this effect was independent of age; in fact, children from 7–8 to 9–10 years were comparably sensitive to the strength of LTM associations in updating. However, older children were more effective in offline inhibitory control.

Time and interference: Effects on working memory

This study tested predictions from the time-based resource-sharing (TBRS) model with a classical verbal working memory (WM) task, where target and non-target information interfere strongly with each other. Different predictions can be formulated according to the dominant perspectives (TBRS and interference hypothesis) on the role of inhibitory control in WM task performance. Here, we aimed to trace the activation of irrelevant information, examining priming effects in a lexical decision task immediately following WM recall. Results indicate the roles of both time and interference constraints in determining task performance. In particular, the role of time available seemed crucial at the highest WM loads (i.e., 3 and 4 memoranda). These were also associated with a higher activation of no-longer-relevant information but, in this case, independently from time available for processing.

Visuospatial working memory in children with autism: the effect of a semantic global organization

It has been reported that individuals with Autism Spectrum Disorders (ASD) perceive visual scenes as a sparse set of details rather than as a congruent and meaningful unit, failing in the extraction of the global configuration of the scene. In the present study, children with ASD were compared with typically developing (TD) children, in a visuospatial working memory task, the Visual Patterns Test (VPT). The VPT array was manipulated to vary the semantic affordance of the pattern, high semantic (global) vs. low semantic; temporal parameters were also manipulated within the change detection protocol. Overall, there was no main effect associated with Group, however there was a significant effect associated with Semantics, which was further qualified by an interaction between the Group and Semantic factors; there was only a significant effect of semantics in the TD group. The findings are discussed in light of the weak central coherence theory where the ASD group are unable to make use of long term memory semantics in order to construct global representations of the array.