The unity and diversity of executive functions and their contributions to complex "frontal lobe" tasks: A latent variable analysis

This individual differences study examined the separability of three often postulated executive functions-mental set shifting ("Shifting"), informatio n updating and monitoring ("Updating"), and inhibition of prepotent respons es ("Inhibition")-and their roles in complex "frontal lobe" or "executive" tasks. One hundred thirty-seven college students performed a set of relativ ely simple experimental tasks that an considered to predominantly tap each target executive function as well as a set of frequently used executive tas ks: the Wisconsin Card Sorting Test (WCST), Tower of Hanoi (TOH), random nu mber generation (RNG), operation span, and dual tasking. Confirmatory facto r analysis indicated that the three target executive functions are moderate ly correlated with one another, but are clearly separable. Moreover, struct ural equation modeling suggested that the three functions contribute differ entially to performance on complex executive tasks. Specifically, WCST perf ormance was related most strongly to Shifting, TOH to Inhibition, RNG to In hibition and Updating, and operation span to Updating. Dual task performanc e was not related to any of the three target functions. These results sugge st that it is important to recognize both the unity and diversity of execut ive functions and that latent variable analysis is a useful approach to stu dying the organization and roles Of executive functions. (C) 2000 Academic Press.