NOVEL DECISION-MAKING IN PATIENTS WITH PREFRONTAL OR POSTERIOR BRAIN-DAMAGE

Patients with lesions of the front al lobes experience greater difficu lties in performing nonroutine tasks, but their ability to cope with n ovel situations has not been studied. We assessed novel and previously practiced decisions in normal subjects and patients with frontal or p osterior brain damage using a unimanual two-choice response time test. Patients with frontal damage had a dramatic impairment on novel decis ion, whereas practiced decision was normal. Relative Judgment Theory a nalysis suggested that the basic disorder concerns the ability to crea te internal referents that are determined from instructions and are su bsequently required to associate the current stimulus with the appropr iate response. The results of the study suggest that the prefrontal co rtex is critical for novel decision making and that it operates mainly at the stage of creation of internal referents that associate some su bsequent event with the selection of appropriate processing. This basi c disorder may underlie some behavioral changes such as apathy and dif ficulty on tests that are sensitive to frontal damage.