Reaction Times in Schizophrenia

Choi, Hyeong Sik; Jeong, Bum Seok; Kim, Han Kyoo; Song, Hyun Joo; Lee, Jae Won; Kim, Chang Yoon

Abstract

The reaction time(RT) has been known to reflect attention that controls the flow of information processing. Extensive research has demonstrated cognitive impairment in schizophrenia subjects using RT tasks. However, little work has been done examining the relative contribution of DT(decision time) and MT(motor time) to slowed RT in schizophrenics. Also, recent investigators have observed that schizophrenic patients exhibit larger intra-individual variability in RT than do normal comparison subjects. The purpose of this study, using multi-stimulus convergent RT task, was to explore the speed of RT, relative contribution of decision time(DT) and motor time(MT) to slowed RT, overall sequential profile in 25 repeated-time measurements in 10 schizophrenic out-patients and 10 normal control subjects. Overall reaction time and decision time were slower in schizophrenic subjects than in normal controls. The motor time was not shown to be significantly different between the two groups with 0.05 significance level, although there was some trend indicating schizophrenic subjects were slower consistently in repreated measurements over time. These results suggested that the slower reaction time in schizophrenic subjects was mostly determined by cognitive component, decision time rather than motor time. Sequential profile of repeated measurements showed greater intraindividual and interindividual variations in schizophrenics than in normal controls. These results indicate that high variabilities are not merely measurement errors but characteristic of schizophrenic psychopathology.