It should be emphasized that the BD subjects to be included on this protocol will have selective deficits (on the basis of neuropsychological test findings and screening to determine candidacy) and will be able to understand the purpose of our studies, the instructions for our tasks, and response demands. Patients who cannot understand the purpose of our studies, or the instructions or response demands of the tasks would not meet entry criteria. Only those subjects who pass the screening will be accepted on the protocol.