Age differences, cerebral arousability, and human intelligence

This report describes an empirical test of the cerebral arousability theory of intelligence which predicts that EEG-intelligence correlations will vary systematically as a function of age-related changes in cerebral arousal. Data were obtained from 76 subjects, in six different age-groups, with equal numbers of males and females in each group. AEP measures evaluated the amplitude, frequency and variability of EEG responses evoked by auditory stimulation. In accordance with arousability theory, but in contrast to an earlier report by D.E. Hendrickson (1982), the results show that there is no simple linear relationship between any of the EEG measures and general intelligence. There is a predicted increase in cerebral arousal during early adulthood with the highest arousal found for the 41–50 age-group and thereafter a steady decline with increasing age. Positive and negative Pearson product-moment correlations were found for variation of cerebral arousal with respect to WAIS ‘verbal’ and ‘spatial’ scores, respectively. These correlations conform exactly to the pattern predicted from arousability theory. Also, as expected from theory, the correlations for the youngest and oldest age-groups were generally greater in magnitude and more likely to be statistically significant with values ranging up to r = 0.78.