Cognitive risk-taking after frontal or temporal lobectomy--I. The synthesis of fragmented visual information.

Patients with unilateral cerebral excisions and control subjects performed two visual tasks in which target items had to be guessed on the basis of partial information. In one task, no points were at stake, but in the second, each cumulatively provided clue was assigned successively lower point-value, these points being risked whenever the subject responded. The right fronto-temporal group chose to guess more often after seeing only one clue than any other group. The right temporal-lobe group and both frontal-lobe groups were impaired at synthesizing the fragmented line-drawings, with patients in the frontal-lobe groups making the most perceptual errors.