Stimulus Intensity Control and the Cortical Evoked Response

Abstract

Cortical evoked potentials to light flashes of 4 intensities and performances on a kinesthetic figural after-effects perceptual task (KFA) were obtained from normal and nonparanoid schizophrenic subjects. In previous studies it had been shown that individual differences in perception of stimulus intensity could be inferred from KFA performance. In this study, it was hypothesized that individuals whose KFA scores indicated a tendency to reduce the perceived intensity of strong stimulation would show a comparable response tendency on a cortical evoked response procedure. Significant correlations were found between evoked response latency and amplitude measures and KFA values in both normal and psychiatric groups. Sex differences in evoked response parameters were also found, males showing a steeper intensity-response function than females. Further, sex was found to be an important moderator variable of the relationship between evoked response measures and KFA values. These findings were interpreted in terms of a theoretical construct regarding a stimulus intensity control mechanism in the central nervous system.