La mémoire de travail joue un rôle central dans le développement cognitif et sa capacité est le meilleur prédicteur des performances dans les activités cognitives complexes et les apprentissages scolaires. Dans le cadre de notre modèle du partage temporel des ressources, trois facteurs principaux sont responsables du développement des capacités de la mémoire de travail. Dans cet article, nous synthétisons les principaux résultats illustrant l’impact de deux de ces facteurs sur le développement, montrant ainsi comment l’accroissement de la quantité d’attention et l’efficacité croissante du mécanisme d’alternance attentionnelle peuvent expliquer le développement des capacités de mémoire de travail.

Working memory has a central role in cognitive development and its capacity is among the best predictors of high-level cognition and school achievement. Within the Time-Based Resource Sharing (TBRS) model, three main factors account for the development of working memory capacity. In this paper, we will review the main empirical evidence sustaining the impact of two of these factors on cognitive development. First, the amount of attention available for cognitive functioning might increase during childhood. Thus, for the same activities, older children would be able to process information faster than younger children. Within working memory span tasks, because the level of activation of memory traces decreases during the processing steps, any reduction of the duration of these steps directly diminishes the time during which the traces decay, and consequently increases the time available for reactivation or refreshing before the next processing step. These two effects jointly induce a stronger activation of the memory traces and a better recall of the to-be-maintained items. Second, because the main hypothesis of the TBRS model is that attention switches to refresh memory traces from processing to maintenance during the processing episodes, the efficiency of the refreshing mechanism should have a direct and strong impact on working memory functioning. An increase in the efficiency of this refreshing during childhood means that older children should take a greater advantage from the short pauses left free between each processing step. The level of activation of the memory traces would be then higher for older than for younger children, resulting in the classically observed increase in span. As a consequence, age-related changes in the efficiency of the refreshing could play a central role in working memory development.