Problem solving deficits after focal cerebral lesions.

Verbal comprehension and naming, identification of categories, as well as problem solving on reasoning and sorting tasks were examined in 57 patients with focal brain lesions and 20 control patients. The results confirmed the prediction that frontal lobe lesions cause a more pronounced deficit in problem solving than posterior lesions. However, patients with left frontal lobe lesions showed verbal inefficiency which possibly disturbed their sorting on the basis of feedback, but the inferiority of the frontal lobe damaged patients on category identification was not secondary to this verbal deficit. As the patients with left posterior lesions did not have marked verbal deficits, the present findings should be confined to patients lacking severe aphasia, which may also disturb problem solving in patients with posterior lesions.