The test performance of ten schizophrenic patients who had undergone bilateral prefrontal lobotomy are compared with those of seven patients of similar diagnosis and vocabulary ability who had not undergone the operation. Rorschach and Binet Tests, and other tests of abstract thinking, learning, planning, deliberation and deliberative behavior, were administered. The major finding was the impairment of the capacity for 'deliberation' and 'deliberative behavior', or of 'prolonged attention', following a prefrontal lobotomy. The lobotomized individuals retained many of their prepsychotic personality traits. A much larger sample of cases is needed to render this finding trustworthy.