RELATIONSHIP BETWEEN CROSSOVER AND MODALITY SHIFT EFFECTS IN SEQUENTIAL REACTION-TIME PERFORMANCE OF SCHIZOPHRENIC-PATIENTS

On the basis of reaction time measurement, two well-known experimental indicators of attentional dysfunctions in schizophrenia were studied. These are the crossover effect (COE), induced by alternating preparat ory intervals, and the modality shift effect (MSE), induced by alterna ting stimulus modalities. For the first time, the relationship between these indicators was examined. Correlations of both indicators with c linical variables such as psychopathology, subjective complaints, dura tion of illness and medication were also analyzed. Subjects were 50 sc hizophrenic inpatients and 50 healthy controls, 21 women and 29 men in each group. While earlier results for COE and MSE were replicable, no correlation between the two was found, leading to the conclusion that they involve different aspects of attention not necessarily impaired to the same extent in all patients.