Performance on working memory (WM) and fluid intelligence tasks (gF) is often highly correlated. However, recent research by Shipstead, Harrison, & Engle (2016) has suggested that dissociable cognitive processes underlie performance on WM and gF tasks, such that WM task performance is contingent upon maintenance of relevant information while gF task performance is contingent upon disengaging from irrelevant information so that updating can occur. The aim of the current study was to test the proposal that the dopamine gating system, a neurological mechanism underlying information encoding and updating, is a plausible mechanism underlying the abilities identified by Shipstead and colleagues that are separately unique to WM and gF. Sixty-three participants completed a task that measured ability to maintain and update information, and is neurologically known to reflect functionality of the dopamine gating system during updating performance. The results indicate that individual differences in updating performance are predicted by gF, but not by WM. This suggests that the ability to disengage from irrelevant information is facilitated by distinct processes in the dopamine gating system, and is a distinguishing component of gF.