The development and impairment of working memory

The term working memory refers to the system used for the temporary maintenance and manipulation of information, a system that is critical for efficient cognitive functioning. One particular model of working memory is described, in which the working memory system is fractionated into three components: an attentional control system termed the central executive, and two modality-specific slave-systems, the phonological loop and the visuospatial sketchpad (Baddeley & Hitch, 1974; Baddeley, 1986). Each of these components of working memory appears to follow a unique developmental trajectory, whilst impairments to the system give rise to highly specific cognitive difficulties. Central executive deficits result in wide-ranging difficulties with general cognitive functioning, and for children lead to learning difficulties within the educational setting. In contrast, impairments of the phonological loop are associated specifically with difficulties in learning the phonological structure of new words. Deficits of the visual spatial sketchpad are less readily identifiable but have been suggested to result in difficulties in the long-term learning of visual and spatial information.