Data will be collected in the context of an open label, randomized clinical trial comparing the efficacy of ziprasidone to the atypical agents, olanzapine and risperidone. This trial will compare the effects of ziprasidone with risperidone or olanzapine on positive and negative psychotic symptoms, mood, and side effects, as well as provide the first comprehensive data on the effects of these drugs on information processing, working memory and dopamine D2 receptor occupancy. These pilot data will allow us to test the hypotheses that 1) ziprasidone will be associated with improvements in information processing and working memory. 2) ziprasidone will be associated with improvements in psychotic symptoms and mood. 3) ziprasidone associated improvements in cognition and behavioral symptoms will be at least as significant as those associated with treatment with olanzapine or risperidone. Finally, we will examine the relative D2 occupancies of these drugs using PET