Visual selective attentional performance under low and high processing load conditions was examined in patients with schizophrenia (n = 20), or bipolar affective disorder-manic type (n = 21) and a group of normal control subjects (n = 18). Although schizophrenic patients demonstrated significantly more impaired cognitive performance than normal controls, bipolar patients were found to be as deviant as the schizophrenic patients on almost all of the performance variables. Positive thought disorder under high processing load demands was moderately correlated with schizophrenic patients' response processing ability. In contrast, negative thought disorder ratings were found to be moderately associated with reaction time performance during high processing demands for both patient groups. These findings are discussed with regard to the relationship between selective attention, visual-motor controlled information processing deficits, and thought disorder in psychosis.