| Fluid intelligence (gF) is a major dimension of variation in cognitive ability, reflecting the capacity to reason and solve problems in novel domains. Furthermore, gF predicts outcomes on various societal measures. Interestingly, numerous studies have demonstrated a strong link between gF and working memory (WM) span. More specifically, it has been suggested that gF and WM span are related because both factors depend upon executive attention---the ability to actively maintain goal-relevant information in the face of interference. Little is known about the specific neural mechanisms underlying individual differences in these factors, the relationship between them, or their association with important societal outcomes. The current study examined the relationships among gF, WM span, and academic success (i.e., college GPA), and the degree to which those associations were explained by the neural mechanisms of executive attention. 120 participants were scanned with 3T event-related fMRI while performing the n-back WM task (3-back condition). Items presented previously in the experiment, but not in the 3-back position, were classified as high-interference lures. Performance and neural activity for lures were hypothesized to be differentially sensitive to executive attention mechanisms. Offline, participants completed two standard measures of gF and four measures of WM span. The two latent variables derived from those measures were highly correlated, and were correlated with performance on lure trials. Furthermore, gF and WM span seemed to be differentially related to neural activity during lure trials compared to other n-back trials, especially in portions of lateral PFC. Most interestingly, both accuracy and activity during lure trials appeared capable of partially mediating the relationship between gF and WM span. GPA was available for a subset of this sample (n = 48). Surprisingly, GPA was not correlated with gF or WM span measures. However, the range of GPA and gF in this subset was too narrow to draw any strong conclusions regarding this finding. The results of this study suggest that the neural mechanisms of executive attention, especially those subserved by portions of bilateral PFC, may act as a basis of variation in gF and WM span, as well as the link between them. |
