Mental representation of knowledge following frontal-lobe lesion: dissociations on tasks using scripts.

Twenty-three frontal-brain-damaged subjects, 10 posterior-brain-damaged subjects and 10 normal controls were compared on script tasks. They were first asked to re-establish the sequential and hierarchical structure of 2 script actions, and then, they were asked to order 2 new scripts which contained aberrant items. Impairments in script information processing were observed only in frontal patients. Of the 23 frontal patient tested 8 made errors in ordering actions, in choosing scenes and in making estimates of action importance in the first task, and they rejected the aberrant elements in the second task. Eleven frontal subjects performed as well as the control subjects in the first task, but used the irrelevant items. The last 4 frontal patients performed as well as the control subjects in both tasks. These results support a possible fractionation of the frontal lobe syndrome.