INDIVIDUAL DIFFERENCES IN STIMULUS INTENSITY RESPONSE.

Differences in the rate of increase of average evoked response (AER) amplitude with increasing intensity of light flash stimuli were studied in 80 male and 40 female college student volunteers. AERs to four intensities of light were recorded from the Ss and a measure of the rate of increase of AER amplitude with increasing stimulus intensity was obtained. Results from Ss tested twice, several weeks apart, showed that the slope of the amplitude intensity function was a stable individual characteristic. The observed amplitude intensity slope was greater in women than in men; vertex-ear leads showed lower slopes than vertex-occiput leads; subject handedness or hemisphere of lead derivation had little effect. Twenty extreme Ss, 10 individuals with the greatest slopes and 10 individuals with an actual decrease in AER amplitude with increasing stimulus intensity (negative slopes), were studied in greater detail. The amplitude-intensity slope was more affected by the absolute intensity of the light than the interstimulus interval or habituation effects. [ABSTRACT FROM AUTHOR]