Dissociating visuo-spatial and verbal working memory: It’s all in the features

Echoing many of the themes of the seminal work of Atkinson and Shiffrin (1968), this paper uses the Feature Model (Nairne, 1988, 1990; Neath & Nairne, 1995) to account for performance in working memory tasks. The Brooks verbal and visuo-spatial matrix tasks were performed alone, with articulatory suppression, or with a spatial suppression task; the results produced the expected dissociation. We used Approximate Bayesian Computation techniques to fit the Feature Model to the data and showed that the similarity-based interference process implemented in the model accounted for the data patterns well. We then fit the model to data from Guérard and Tremblay (2008); the latter study produced a double dissociation while calling upon more typical order reconstruction tasks. Again, the model performed well. The findings show that a double dissociation can be modelled without appealing to separate systems for verbal and visuo-spatial processing. The latter findings are significant as the Feature Model had not been used to model this type of dissociation before; importantly, this is also the first time the model is quantitatively fit to data. For the demonstration provided here, modularity was unnecessary if two assumptions were made: (1) the main difference between spatial and verbal working memory tasks is the features that are encoded; (2) secondary tasks selectively interfere with primary tasks to the extent that both tasks involve similar features. It is argued that a feature-based view is more parsimonious (see Morey, 2018) and offers flexibility in accounting for multiple benchmark effects in the field

Order Recall in Verbal Short-Term Memory is Influenced by Semantic Activation

It has recently been suggested that order recall in short-term memory tasks is influenced by the level of activation of items in the lexico-semantic network. According to the Activated Network view, increasing the level of activation of an item would increase the probability of observing a migration of the item toward the beginning of the list (Poirier et al., 2015). We tested this prediction by manipulating the orthographic neighbourhood of to-be-recalled items. In Experiment 1, the first three items of a 7-item list were orthographic neighbours of the target item in Position 5. As predicted, at recall, the target item migrated more toward the beginning of the list than control items. In Experiment 2, all list items were orthographic neighbours of the target item located on Position 4, 5, or 6. Compared to control items, the target item migrated more toward the beginning than the end of the list

Mécanique de l'arbre sur pied : les relevés dendrométriques classiques pour quantifier les efforts gravitationnels supportés par un tronc - leurs limites

Le fût d'un arbre sur pied est soumis à l'action de la pesanteur, qui induit un effet de flexion sur un arbre déséquilibré. La qualification de cette action réclame donc d'évaluer non seulement la masse de l'arbre, mais aussi son déséquilibre, c'est-à-dire la position de son centre de gravité dans un plan horizontal. Une méthode d'estimation de cette position à partir de relevés dendrométriques simples (mesure d'une inclinaison du fût, de huit rayons de la projection au sol du houppier) est proposée. Appliquée à 9 peupliers, elle permet de classer les individus en trois groupes : droits, inclinés, flexueux. Confrontée aux résultats d'un essai mécanique de suppression de la masse supportée, elle apparaît suffisante pour estimer la direction de l'effort de flexion sur les individus de conformation simple, droits ou inclinés, mais doit être affinée dans les cas plus complexes. L'essai comme la modélisation confirment en outre la prépondérance des effets de flexion sur ceux de compression, même sur des individus apparemment équilibrés. (Résumé d'auteur

Forward and backward recall: Different visuospatial processes when you know what’s coming

In an immediate memory task, when participants are asked to recall list items in reverse order, benchmark memory phenomena found with more typical forward recall are not consistently reproduced. These inconsistencies have been attributed to the greater involvement of visuospatial representations in backward than in forward recall at the point of retrieval. In the present study, we tested this hypothesis with a dual-task paradigm in which manual-spatial tapping and dynamic visual noise were used as the interfering tasks. The interference task was performed during list presentation or at recall. In the first four experiments, recall direction was only communicated at the point of recall. In Experiments 1 and 2, fewer words were recalled with manual tapping than in the control condition. However, the detrimental effect of manual tapping did not vary as a function of recall direction or processing stage. In Experiment 3, dynamic visual noise did not influence recall performance. In Experiment 4, articulatory suppression was performed on all trials and manual tapping was added on half of them. As in the first two experiments, manual tapping disputed forward and backward recall to the same extent. In Experiment 5, recall direction was known before list presentation. As predicted by the visuospatial hypothesis, when manual tapping was performed during recall, its detrimental effect was limited to backward recall. Overall, results can be explained by calling upon a modified version of the visuospatial hypothesis

A Curved Honulo improves your Short-Term and Long-Term Memory

During his distinguished career, Bill Hockley contributed to memory research in many ways, with work characterized by rigorous and innovative experimental designs. One of the areas he has explored is that of memory for associative information. We echo this interest here and attempt to emulate his careful experimental attitude. We report four experiments which examined how previously established links can support the development of new episodic associations. More specifically, we tested the idea that sound-symbolism links can support learning of new associations. Sound-symbolism links are relationships between phonemes and object characteristics that participants find natural − even if they have never encountered the items before. For instance, the nonword “honulo” is more readily seen to refer to a shape with curved contours than to a shape that has sharp angles. In Experiment 1, 70 participants studied three pairs and their memory for the associations between the members of each pair was tested in a paired-recognition task. Results demonstrate that sound-symbolism associations support the learning of new associations. Experiment 2 confirmed that the effect is replicated in a between-participants design. In Experiment 3, we replicated the findings with a 30-second filled interval between presentation and test, and in Experiment 4, we extended the delay to 2 minutes, establishing that the pattern is also found with a paradigm more typical of episodic memory. The results are discussed in terms of the importance of associative memory, while referring to some of the ideas Bill Hockley championed in his own work

Working memory constrains long-term memory in children and adults: memory of objects and bindings

We explored how individual and age-related differences in working memory (WM) capacity affected subsequent long-term memory (LTM) retrieval. Unlike past studies, we tested WM and LTM not only for items, but also for item–color bindings. Our sample included 82 elementary school children and 42 young adults. The participants performed a WM task with images of unique everyday items presented sequentially at varying set sizes in different colors. Later, we tested LTM for items and item–color bindings from the WM task. The WM load during encoding constrained LTM, and participants with a higher WM capacity retrieved more items in the LTM test. Even when accounting for young children’s poor item memory by considering only the items that they did remember, they exhibited an exacerbated difficulty with remembering item–color bindings in WM. Their LTM binding performance, however, as a proportion of remembered objects, was comparable to that of older children and adults. The WM binding performance was better during sub-span encoding loads, but with no clear transfer of this benefit to LTM. Overall, LTM item memory performance was constrained by individual and age-related WM limitations, but with mixed consequences for binding. We discuss the theoretical, practical, and developmental implications of this WM-to-LTM bottleneck

A Model of the Production Effect over the Short-Term: The Cost of Relative Distinctiveness

The production effect relates to the better memory of words read aloud during a study phase compared to silently read items. Here, we examined the production effect for memory over the short-term. In long-term memory tasks, the effect generates a complex pattern of results where production interacts with memory task and list composition. Within an immediate ordered recall paradigm, involving both item and order information, we tested the item-order account, recently called upon to explain the production effect. We also analysed results as a function of serial position. Results of the first five experiments were highly consistent, but hard to reconcile with the item-order account. Instead, we put forward an interpretation based on relative distinctiveness and the costs of the richer encoding associated with production. The predictions we derived from this interpretation were supported in the final experiment. Moreover, we tested the interpretation through a new version of the Feature Model. Overall, the work highlights the value of the production effect as a prototypical distinctiveness phenomenon illuminating the interaction of encoding and retrieval processes, the value of feature-rich representations, and the costs that can be associated with feature-generating distinctive processing

The Production Effect Over the Long Term: Modeling Distinctiveness Using Serial Positions

The production effect is a well-established finding: If some words within a list are read aloud, that is, produced, they are better remembered than their silently read neighbors. The effect has been extensively studied with long-term memory (LTM) tasks. Recently, using immediate serial recall and short-term order reconstruction, Saint-Aubin et al. (2021) reported informative interactions between the production effect and serial positions. Here, we asked whether these interactions would also be observed with the LTM tasks used in the field. In Experiment 1, pure and mixed lists of 8 words were presented in both order reconstruction and free recall tasks, with a 30-second filled retention interval. In Experiment 2, the list length was extended to 24 words; in Experiment 3, 10-word lists were used with a 2-minute retention interval. Results from all experiments aligned well with those observed in short-term memory. With mixed lists, where produced and silently read words alternated, produced items were better recalled, leading to sawtooth serial position curves. With pure lists, produced items were better recalled when studied in the last serial positions, but they were less well recalled for the primacy positions. Results were readily accounted for by the Revised Feature Model, originally developed to explain short-term memory performance. The findings and model suggest that produced items are encoded with more item-specific, modality-related features, that this generates a relative distinctiveness advantage in short- and long-term memory. However, the richer encoding comes at a cost: it appears to disrupt rehearsal

Complete mitochondrial DNA sequences provide new insights into the Polynesian motif and the peopling of Madagascar

More than a decade of mitochondrial DNA (mtDNA) studies have given the 'Polynesian motif' renowned status as a marker for tracing the late-Holocene expansion of Austronesian speaking populations. Despite considerable research on the Polynesian motif in Oceania, there has been little equivalent work on the western edge of its expansion - leaving major issues unresolved regarding the motif's evolutionary history. This has also led to considerable uncertainty regarding the settlement of Madagascar. In this study, we assess mtDNA variation in 266 individuals from three Malagasy ethnic groups: the Mikea, Vezo, and Merina. Complete mtDNA genome sequencing reveals a new variant of the Polynesian motif in Madagascar; two coding region mutations define a Malagasy-specific sub-branch. This newly defined 'Malagasy motif' occurs at high frequency in all three ethnic groups (13-50%), and its phylogenetic position, geographic distribution, and estimated age all support a recent origin, but without conclusively identifying a specific source region. Nevertheless, the haplotype's limited diversity, similar to those of other mtDNA haplogroups found in our Malagasy groups, best supports a small number of initial settlers arriving to Madagascar through the same migratory process. Finally, the discovery of this lineage provides a set of new polymorphic positions to help localize the Austronesian ancestors of the Malagasy, as well as uncover the origin and evolution of the Polynesian motif itself

The pseudophosphatase MK-STYX interacts with G3BP and decreases stress granule formation

MK-STYX [MAPK (mitogen-activated protein kinase) phospho-serine/threonine/tyrosine-binding protein] is a pseudophosphatase member of the dual-specificity phosphatase subfamily of the PTPs (protein tyrosine phosphatases). MK-STYX is catalytically inactive due to the absence of two amino acids from the signature motif that are essential for phosphatase activity. The nucleophilic cysteine residue and the adjacent histidine residue, which are conserved in all active dual-specificity phosphatases, are replaced by serine and phenylalanine residues respectively in MK-STYX. Mutations to introduce histidine and cysteine residues into the active site of MK-STYX generated an active phosphatase. Using MS, we identified G3BP1 [Ras-GAP (GTPase-activating protein) SH3 (Src homology 3) domain-binding protein-1], a regulator of Ras signalling, as a binding partner of MK-STYX. We observed that G3BP1 bound to native MK-STYX; however, binding to the mutant catalytically active form of MK-STYX was dramatically reduced. G3BP1 is also an RNA-binding protein with endoribonuclease activity that is recruited to ‘stress granules’ after stress stimuli. Stress granules are large subcellular structures that serve as sites of mRNA sorting, in which untranslated mRNAs accumulate. We have shown that expression of MK-STYX inhibited stress granule formation induced either by aresenite or expression of G3BP itself; however, the catalytically active mutant MK-STYX was impaired in its ability to inhibit G3BP-induced stress granule assembly. These results reveal a novel facet of the function of a member of the PTP family, illustrating a role for MK-STYX in regulating the ability of G3BP1 to integrate changes in growth-factor stimulation and environmental stress with the regulation of protein synthesis