Individual differences in working memory capacity and attentional control

Visual working memory (WM) has a very limited online capacity making it considerably important to control the gating of encoding into WM. Recent studies have suggested that attention control is of importance in doing so, especially the time needed to disengage. However, the disengagement mechanism operates on a later stage of processing after the initial selection of information has already been initiated. We assume that individual differences in WM capacity are also driven by individual variations in the voluntary engagement of attention. In 2 experiments we investigated whether individuals with high- and low-WM capacity differ in the efficiency and speed of this attention control process. We realised different versions of the task in which different amounts of attention control were necessary, a more automatically triggered allocation of attention and a voluntary initiation of attention engagement, respectively. We further manipulated the time course to look for differences in the latency of attention control. The results revealed that participants with low-WM capacity were less effective to exhibit voluntary attention control processes and they were also slower in doing so compared with high-WM capacity individuals. However, this effect seems to be partly moderated by the ability to update the current task set. If the trial structure did not require task set updating smaller individual differences involving WM capacity could be found.Keywords: working memory capacity, attention control, individual differencesResumeLa memoire de travail (MT) visuelle dispose de capacites tres limitees en ligne. Il devient alors tres important de controler l'encodage selectif dans la MT. Les recentes etudes ont montre que le controle de l'attention joue un role important, particulierement au niveau du temps relie au desengagement. Or, le mecanisme de desengagement se produit a un stade ulterieur du traitement, c'est-a -dire une fois que la premiere selection de l'information a ete initiee. Nous emettons l'hypothese que les differences individuelles au niveau de la capacite de la MT sont egalement le resultat de variations individuelles au niveau de l'engagement volontaire de l'attention. A l'aide de deux experiences, nous avons cherche a savoir si les individus dotes d'une faible capacite de MT et d'une forte capacite de MT divergeaient en ce qui a trait a l'efficacite et a la vitesse de ce procede de controle de l'attention. Nous avons realise differentes versions de la tâche selon lesquelles differents niveaux de controle d'attention etaient requis, une attribution de l'attention davantage declenchee de maniere automatique et une initiation volontaire de l'engagement de l'attention, respectivement. Nous avons ensuite manipule la duree afin de detecter des ecarts au niveau du temps de latence du controle d'attention. Les resultats ont montre que les participants dotes d'une faible capacite de MT etaient moins efficaces a afficher les procedes de controle d'attention volontaire et le faisaient plus lentement comparativement aux individus dotes de forte capacite de MT. Cet effet semble toutefois partiellement modere par la capacite de mise a jour de l'ensemble de tâches actuel. Si la structure de l'essai ne necessitait pas la mise a jour de l'ensemble de tâches, des ecarts individuels plus faibles impliquant la capacite de MT pourraient etre detectes.Mots-cles : capacite de la memoire de travail, controle de l'attention, ecarts individuels.Human visual working memory (WM) is a form of online work space that keeps about three to four objects in an accessible state. The first notion of the term WM goes back to Baddeley and Hitch in the 1970s (Baddeley & Hitch, 1974). They highlighted that WM is more than a passive store for the temporary maintenance of information (see immediate memory, Miller, 1956) but a component that actively maintains, manipulates, and updates attended items. Hence, WM is a cognitive system that allows more than retaining information over a period of time. …