Wisconsin Card Sorting Test performance in patients with focal frontal andposterior brain damage: effects of lesion location and test structure on separable cognitive processes

Forty-six patients with single focal lesions (35 frontal, ii nonfrontal) we re administered the Wisconsin Card Sorting Test (WCST) under three conditio ns of test administration. The three conditions varied in the amount of ext ernal support provided via specificity of instructions. The WCST, while a m ultifactorial test, is specifically sensitive to the effects of frontal lob e damage if deficits in language comprehension and visual-spatial search ar e controlled. There is also specificity of functioning within the frontal l obes: patients with inferior medial frontal lesions, unilateral or bilatera l, were not impaired on the standard measures although they had increased l oss of set when informed of the sorting categories. Verbal instructions may provide a probe to improve diagnosis and prognosis, assessment of the pote ntial efficacy of treatment, and the time frame of plasticity of specific c ognitive operations. (C) 2000 Elsevier Science Ltd. All rights reserved.