Speed and flexibility on word fluency tasks after focal brain lesions.

It was predicted that frontal lobe damaged patients are slower on word fluency tasks, especially on the generation of words beginning with a particular letter, and less flexible ("stuck-inset") on category alternation than patients with posterior lesions, whereas the latter commit a higher number of repetitions ("recurrent perseverations") than the former. Twenty-nine anterior and 31 posterior brain damaged patients were requested to say as quickly as possible (1) 20 animal names, (2) 10 words beginning with the letter S, and (3) alternately animals and S-words, 10 from each category without repeating the words already used in these tasks. The results failed to confirm the predictions.