Impact de la nature et du rythme de réalisation de la tâche secondaire dans les tâches d'empan et de mémoire de travail

National audienceLes tâches d'empan de mémoire de travail sont des tâches dans lesquelles des items doivent être maintenus en mémoire à court terme pendant qu'un traitement concurrent est effectué. Le but de la présente étude était de déterminer si, comme le soutient le modèle de partage temporel des ressources (Barrouillet, Bernardin, & Camos, 2004), les traitements gênent le maintien parce que les deux composantes entrent en compétition pour des processus communs ou plus simplement parce que les stratégies de maintien des items à rappeler sont perturbées par l'intrusion de l'information à traiter simultanément. Quatre-vingt sujets adultes étaient soumis à une tâche d'empan où ils devaient maintenir des lettres en même temps qu'ils devaient juger soit de la parité soit de la position spatiale de nombre présentés successivement à l'écran. Par ailleurs, ces nombres apparaissaient à un rythme régulier et donc prévisible ou bien aléatoire. Conformément à nos attentes, et contrairement à l'hypothèse d'une perturbation des stratégies de maintien, les jugements de parité qui nécessitent des récupérations en mémoire entraînaient de plus faibles empans que la tâche spatiale qui ne requiert qu'une sélection de réponse alors que le rythme de réalisation de la tâche secondaire n'avait pas d'effet sur les empans

Motor programming disrupts verbal maintenance

The functional organization of the PFC from anterior to posterior regions reflects a hierarchy of cognitive control whereby progressively anterior sub-regions are associated with higher-order control. The present study aimed at providing behavioral evidence for two predictions issuing from this cascade model. First, even the lower-most sub-part of the cognitive control hierarchy, i.e. motor programming, should interfere with higher controlled processes such as maintenance in working memory. Second, this effect should be commensurate with the time during which control is required. In a computer-paced complex span task, adults had to maintain letters while they performed a secondary task. The demand imposed by this task was manipulated either at the selection or at the motor programming stage of response preparation. Results revealed that both manipulations have a disruptive effect on verbal memory, and that this effect is commensurate with the extra-time during which response selection and motor programming require cognitive control

Is the influence of working memory capacity on high-level cognition mediated by complexity or resource-dependent elementary processes?

The aim of this study was to investigate the involvement of working memory (WM) in elementary activities and the nature of the mechanisms mediating the influence of WM capacity on high-level cognition. We demonstrate that even elementary activities such as reading digits, subitizing small arrays of dots, or solving simple additions like 3+1 are sensitive to individual differences in WM capacity. Moreover, we demonstrate that a complex task such as counting large arrays of dots involving these elementary activities as processing steps does not induce WM-related differences beyond what can be predicted from the concatenation of differences elicited by the task's elementary constituents. In line with the time-based resource-sharing model, these results suggest that the influence of WM capacity on high-level cognition is mediated by the impact of a basic general-purpose resource that affects each atomic step of cognitio

Time causes forgetting from working memory

Although forgetting in the short term is a ubiquitous phenomenon, its exact causes remain undecided. The aim of the present study was to test the temporal decay hypothesis according to which memory traces fade away with time when attention is diverted by concurrent activities. In two experiments involving complex span tasks, adults were asked to remember series of items (either letters or spatial locations) while verifying multiplications. The duration of processing was manipulated by presenting multiplications either in word (three    ×    four    =    twelve) or digit (3    ×    4    =    12) format, the former taking longer to solve, while the time available to restore memory traces after each operation was kept constant across conditions. In line with the temporal decay hypothesis, the longer solution times elicited by solving word multiplications resulted in poorer recall performance. The fact that longer processing times had a comparable effect on both verbal and visuospatial memory and that the difference between conditions remained stable from the first to the last trials makes it difficult to account for these findings by assuming that forgetting is exclusively due to representation-based interference or buildup of proactive interferenc

Experimental investigation of laminar and turbulent displacement of residual oil film

Residual oil films on pipe walls are a common occurrence in industrial processes, and their presence can significantly impact system efficiency and performance. However, the mechanisms that govern oil film removal by an immiscible displacing fluid from the internal walls of pipes under different flow regimes, including laminar and turbulent flows, are not yet fully understood. In this study, we investigated the impact of displacing fluid flow regime, injected volume, displacement time, and wall shear stress on the efficiency of residual oil film removal in a pipe. We first verified the applicability of our developed oil film measurement method for the use in vertical pipes, and found that gravity did not significantly affect the long-term oil film removal process. We verified that our results from the laminar cases agree with the theoretical thin-film limit scaling under reasonable assumptions of constant shear stress and negligible surface tension. We then examined the displacement efficiency of residual oil film under laminar and turbulent flow regimes. Our experimental results revealed that the onset of turbulence of displacing fluid played an important role in the efficient removal of residual oil film, with an optimal range of Reynolds numbers (7000–8000) when the injected volume of displacing fluid is limited. Furthermore, we explored the combined effect of wall shear stress and displacement time on the displacement process under different turbulent flow regimes. We found that the intermediate turbulent regime was the most efficient for achieving cleaning in a limited time, while the highly turbulent regime proved to be the most effective for achieving complete cleaning over a longer time period. These findings have important implications for oil recovery and pipeline maintenance and provide valuable insights into optimizing the removal of residual oil film in pipes.publishedVersio

Development of a novel experimental technique for the measurement of residual wall layer thickness in water-oil displacement flows

The effective removal and displacement of fluids is important in many industrial and environmental applications, such as for operation and cleaning of process equipment, fluid injection in porous media for oil recovery or aquifer remediation, or for achieving subsurface zonal isolation in new or abandoned wells. The accurate measurement of the residual fluid wall film left behind after displacement by a cleaning fluid is a long-standing challenge, particularly so for very thin fluid films where the thickness can be of the order of micrometer. We focus on the characterization of oil films left on the wall of a horizontal pipe after the pipe has been displaced by water, and develop a novel, non-intrusive analytical technique that allows the use of relevant pipe materials. The oil that originally occupies the pipe is stained by a hydrophobic dye Nile red, and an intermediate organic solvent is used to collect the residual oil volume that remains after displacing the pipe with a known volume of water. Finally, ultraviolet-visible spectroscopy is used to measure the Nile red concentration in the collected fluid, which is proportional to the residual volume of oil in the pipe. We demonstrate the methodology by conducting experiments where the displacing fluid is injected at two different imposed velocities, and where the injected fluid volume is varied. As expected, we find a gradual thinning of the oil film with increasing injected fluid volume. We compare the measured film thicknesses to a displacement model based on the steady velocity profile in a pipe, and find that experiments consistently produce smaller film thicknesses. This developed technique allows quantification of displacement and cleaning mechanisms involved in immiscible displacements at laminar, transitional and turbulent regimes, for different non-Newtonian fluid pairs, and for different realistic pipe materials and surface roughnesses.publishedVersio

Resource-sharing in multiple component working memory

Working memory research often focuses on measuring the capacity of the system and how it relates to other cognitive abilities. However, research into the structure of working memory is less concerned with an overall capacity measure but rather with the intricacies of underlying components and their contribution to different tasks. A number of models of working memory structure have been proposed, each with different assumptions and predictions, but none of which adequately accounts for the full range of data in the working memory literature. We report 2 experiments that investigated the effects of load manipulations on dual-task verbal temporary memory and spatial processing. Crucially, we manipulated cognitive load around the measured memory span of each individual participant. We report a clear effect of increasing memory load on processing accuracy, but only when memory load is increased above each participant’s measured memory span. However, increasing processing load did not affect memory performance. We argue that immediate verbal memory may rely both on a temporary phonological store and on activated traces in long-term memory, with the latter deployed to support memory performance for supraspan lists and when a high memory load is coupled with a processing task. We propose that future research should tailor the load manipulations to the capacities of individual participants and suggest that contrasts between models of working memory may be more apparent than real

The effects of verbal and spatial memory load on children's processing speed

Examining the impact of maintenance on processing speed allows us to test whether storage and processing resources are shared. Comparing these relationships in children of different ages allows further insight into whether one or multiple resources for these operations must be assumed and whether remembering is proactive throughout childhood. We tested 185 4-6 and 8-10 year-old children using adaptive complex span tasks, in which simple judgments were interleaved between to-be-remembered items. The adaptiveness of our tasks ensured that all participants frequently correctly recalled the items. If storage and processing require a single resource, and if participants serially reactivate the memoranda in between processing episodes, processing response times should increase with serial position of the processing judgment within lists. We observed different within-list dynamics for each age group. Older children’s processing judgments slowed gradually when more than two memory items were maintained. In contrast, younger children showed no evidence of slower processing with increasing memory load. Our results support models of working memory that assume that some common resource is responsible for verbal and spatial storage and processing. They also support the notion that remembering becomes more proactive as children mature

What is attentional refreshing in working memory?

Working memory is one of the most important topics of research in cognitive psychology. The cognitive revolution that introduced the computer metaphor to describe human cognitive functioning called for this system in charge of the temporary storage of incoming or retrieved information to permit its processing. In the past decades, one particular mechanism of maintenance, attentional refreshing, has attracted an increasing amount of interest in the field of working memory. However, this mechanism remains rather mysterious, and its functioning is conceived in very different ways across the literature. This article presents an up-to-date review on attentional refreshing through the joint effort of leading researchers in the domain. It highlights points of agreement and delineates future avenues of research

Progressions scolaires, mémoire de travail et origine sociale : quels liens à l’école élémentaire ?

Issu d’une recherche portant sur la structure et l’évolution des acquisitions à l’école élémentaire, cet article se focalise sur les liens entre les apprentissages scolaires et les capacités cognitives appréhendées par la mémoire de travail. Reposant sur une approche longitudinale, l’article vise à mettre en évidence la relation qui existe entre la mémoire de travail et les acquisitions scolaires au cours du cycle III. Le lien entre mémoire de travail et origine sociale est également examiné. Les résultats offrent des pistes de réflexion en matière de politique éducative, notamment quant au développement d’activités susceptibles de réduire les écarts sociaux et cognitifs entre les élèves.Based on some research work on the structure and evolution of knowledge acquisitions in elementary school, this article focuses on the links between school learning and cognitive skills acquired using task memory. Based on a longitudinal approach, the article aims at bringing out the link that exists between task memory and school knowledge acquisitions in grades 3 4 and 5. The link between task memory and social background is also studied. The results give us new fields for thoughts on educational policy especially regarding activities that could reduce the social and cognitive differences between children.Nacido de una investigación que trata de la estructura y la evolución de las adquisiciones en la escuela elemental, este artículo se centra en las relaciones entre los aprendizajes escolares y las capacidades cognoscitivas comprendidas por la memoria de trabajo. Descansando en un enfoque longitudinal, el artículo tiende a evidenciar la relación que existe entre la memoria de trabajo y las adquisiciones escolares durante el ciclo III. También se estudia la relación entre memoria de trabajo y origen social. Los resultados ofrecen pistas de reflexión en materia de política educativa, sobre todo en lo que se refiere al desarrollo de actividades capaces de reducir las diferencias sociales y cognoscitivas entre los alumnos.Dieser Artikel stammt aus einer Forschungsarbeit über Struktur und Entwicklung der Erwerbungen in der Grundschule und betrachtet die Verbindungen zwischen dem Schulwissen und den kognitiven Fähigkeiten, die über das Arbeitsgedächtnis erfasst werden. Auf einer longitudinale Herangehensweise beruhend zielt der Artikel darauf ab, die Beziehung zwischen dem Arbeitsgedächtnis und den Schulischen Erwerbungen im 3. Zyklus zu betonen. Die Ergebnisse bieten Denkanstöße über die Erziehungspolitik, besonders was die Entwicklung von Aktivitäten betrifft, die imstande wären, den sozialen und kognitiven Abstand zwischen Schülern zu vermindern