Blair equates the constructs of working memory (WM), executive function, and general fluid intelligence (gF). We argue that there is good reason not to equate these constructs. We view WM and gF as separable but highly related, and suggest that the mechanism behind the relationship is controlled attention – an ability that is dependent on normal functioning of the prefrontal cortex. (Published Online April 5 2006).

Individuals may differ in the general-attention executive component or in the subordinate domain-specific “slave” components of working memory. Tasks requiring sustained memory representations across attention shifts are reliable, valid indices of executive abilities. Measures emphasizing specific processing skills may increase reliability within restricted samples but will not reflect the attention component responsible for the broad predictive validity of span tasks.