Fractionating frontal lobe functions: factors of the Milwaukee Card Sorting Test

The Milwaukee Card Sorting Test (MCST), a modification of the Wisconsin Card Sorting Test (WCST), was administered to 71 geriatric, orthopedic or neurologic patients. The MCST requires that participants verbalize prior to sorting, thus enabling quantification of separate, elemental executive abilities needed for card sorting performance. A preliminary factor analysis yielded three factors, corresponding to elemental executive abilities of forming, maintaining, and switching mental set. Results are discussed as they apply to understanding the cognitive structure of card sorting tasks to revealing different performances associated with behaviorally distinct executive deficits, and to suggesting anatomical substrates underlying the three factors.