EEG-Averaged Evoked Response and Perceptual Variability in Schizophrenics

Abstract

PERCEPTUAL and cognitive studies of schizophrenic patients characteristically reveal great variability. Not only does the performance of schizophrenics on psychological tests typically cover a much broader response range than that of nonschizophrenics, but individual performance shows great variability across time. 1 By selecting representatives of two schizophrenic subtypes as subjects for this study, we hoped to reduce interindividual variability, thus enabling ourselves to observe intraindividual variability more clearly. The two subtypes, nonparanoid long-term process and paranoid short-term reactive, have clinical characteristics often thought to be consistently associated with markedly different perceptual behavior patterns. 1 To test the hypothesis that the two groups show contrasting perceptual patterns, two psychophysical tasks and an average evoked response (AER) measure were administered. In previous researches, a correlation was demonstrated in normal waking-state subjects between reponsiveness on a kinesthetic figural aftereffects (KFA) procedure and responsiveness on an AER