Relationship between exploratory eye movement, P300, and reaction time in schizophrenia.

Aims:  Exploratory eye movement (EEM), P300 and reaction time (RT) tests may relate to the important parts of information processing in the human brain. Therefore the aim of the present study was to compare EEM, P300 and RT test data in schizophrenic and normal control groups to investigate whether schizophrenic patients have information processing abnormalities. In addition, the potential correspondence between the three tests was examined in order to investigate the information processing dysfunctions seen in schizophrenic patients. Methods:  The EEM, P300 and RT performances were recorded in 34 schizophrenic and 36 normal control subjects. Ten parameters were measured: four from the EEM test (number of eye fixations, total eye scanning length, cognitive search score and responsive search score [RSS]); two from the P300 test (amplitude and latency); and four from the RT test (simple reaction time, index of reaction time crossover [IRT-crossover], set index and coefficient of variation). Results:  These parameters in the schizophrenic patients differed significantly from those in the control group. Additionally, there was a significant correlation between the RSS and the IRT-crossover in the schizophrenic patients. Conclusion:  The present group comparisons (schizophrenia vs normal controls) are consistent with previous studies in that the abnormalities in EEM, P300 and RT tests in schizophrenic patients were able to be replicated. Moreover, based on the former psychological theory, it is reasonable to propose that the RSS is associated with the IRT-crossover. The present results may contribute to elucidation of the pathophysiological signature of schizophrenia.