Evaluation of cognitive ability in patients with schizophrenia or schizoaffective disorder both before and after a switch from risperidone to aripiprazole may reveal some of the cognitive changes that correlate with the improved response, better side effect profile, and effects on other components of the negative symptom array. Further, examination of brain functional activity using functional magnetic resonance imaging (fMRI) during a verbal learning task, as well as behavioral performance and associated electroencephalographic (EEG) data of episodic memory, working memory and intermediate term verbal memory collected with the Sustained Attention and Memory Brain Function Test (SAM-BFT), may also provide data showing the neural correlates of these changes in cognition.