Evoked Potential Amplitude Change Related to Intelligence and Arousal

Using a sample of 94 adult subjects, relationships between measures of intelligence and the rate of decrease in amplitude of the average evoked potential (AEP) were examined in some detail. It was found that the rate of AEP amplitude decrease from a condition of high extrinsic inducement to activation to a condition of low extrinsic inducement to activation was significantly correlated with fluid intelligence (r= .24) and its subprocesses, but not with crystallized intelligence. This finding was interpreted as indicating that the AEP shift measure and the fluid intelligence measures indicate a kind of adaptive flexibility (or plasticity) of intellectual functioning. The results suggested that this is not a flexibility capacity that decreases significantly with aging in adulthood.