Individual Differences in Working Memory Capacity and What They Tell Us About Controlled Attention, General Fluid Intelligence, and Functions of the Prefrontal Cortex

Abstract

FIVE CENTRAL FEATURES OF THE THEORY Working memory is a system consisting of those long-term memory traces active above threshold, the procedures and skills necessary to achieve and maintain that activation, and limited-capacity, controlled attention. The specific features of our model include: (1) Domain-free, limited-capacity controlled attention. (2) Domain-specific codes and maintenance (phonological loop and visuospatial sketchpad are two examples but the potential number of such codes is large). (3) Individual differences in both 1 and 2, but individual differences in capacity for controlled processing are general and possibly the mechanism for general fluid intelligence. Although people can, with practice and expertise, circumvent the abiding limitations of controlled attention in quite specific situations, the limitations reemerge in novel situations and even in the domain of expertise if the situation calls for controlled processing. (4) Limited-capacity, controlled processing is required for maintaining temporary goals in the face of distraction and interference and for blocking, gating, and/or suppressing distracting events. (5) The dorsolateral prefrontal cortex (PFC) and associated structures mediate the controlled processing functions of working memory. We also argue that individual differences in controlled processing represent differences in functioning of the PFC. A number of intellectual influences have served to shape our thinking about working memory (WM) and its evolution as a construct separate from that of short-term memory (STM).