Diagnostic utility of the Thurstone Word Fluency Test in neuropsychological evaluations.

Previous research has found that verbal associative fluency tasks are sensitive to the presence of cerebral lesions and more sensitive to frontal lobe and left hemisphere lesions than to other focal lesions. The present study investigated the diagnostic utility of the Thurstone Word Fluency Test (TWFT), a test of written verbal fluency, in detecting and localizing cerebral lesions. Using results from 203 brain-damaged and 134 normal subjects, we found that TWFT performance is affected by cerebral damage generally. At the same time, it is more impaired by frontal than by nonfrontal, by left than by right hemisphere, and by left frontal than by right frontal lesions. This test does not discriminate focal frontal from diffuse lesions. Stepwise discriminant function analyses indicated that the TWFT adds to the Halstead-Reitan Battery in discriminating focal frontal from nonfrontal lesions, but not in discriminating left hemisphere from right hemisphere lesions. Only markedly impaired TWFT performances had lateralizing significance.