Working memory is (almost) perfectly predicted by g

This article analyzes if working memory (WM) is especially important to understand g. WM comprises the functions of focusing attention, conscious rehearsal, and transformation and mental manipulation of information, while g reflects the component variance that is common to all tests of ability. The centrality of WM in individual differences in information processing leads to some cognitive theorists to equate it with g. There are several studies relating WM with psychometric abilities like reasoning, fluid intelligence, spatial visualization, spatial relations, or perceptual speed, but there are very few studies relating WM with g, defined by several diverse tests. In three studies, we assessed crystallised intelligence (Gc), spatial ability (Gv), fluid intelligence (Gf), and psychometric speed (Gs) using various tests from the psychometric literature. Moreover, we assessed WM and processing speed (PS). WM tasks involve storage requirements, plus concurrent processing. PS tasks measure the speed by which the participants take a quick decision about the identity of some stimuli; 594 participants were tested. Confirmatory factor analyses yielded consistently high estimates of the loading of g over WM (96 on average). WM is the latent factor best predicted by g. It is proposed that this is so because the later has much in common with the main characteristic of the former. (C) 2004 Elsevier Inc. All rights reserved.