A test of the hendrickson postulate that reduced EEG response variance causes increased aep contour length: Implications for the ‘neural transmission errors’ theory of intelligence

EEG responses to auditory tones were recorded from 76 human subjects in six different age groups with equal numbers of males and females in each group. Care was taken to reproduce the conditions described by D. E. Hendrickson (1982) who had earlier reported high correlations between intelligence test scores and her new ‘string’ and ‘variance’ measures of EEG response differences. The results obtained in the present study show that the Hendrickson string variable derives from EEG activity in the high frequency band whereas the Hendrickson variance variable derives from activity in the low frequency band. In addition, there is a high positive correlation between the string variable and the variance of corresponding high frequency activity in individual sweeps. These results disprove the Hendricksonsʹ ‘neural transmission errors’ theory of intelligence which requires a negative correlation between the number and amplitude of peaks in the averaged evoked potential (AEP) waveform and the variance of corresponding activity in the individual EEG epochs from which the AEP is derived. It is concluded that the Hendrickson theory fails at the critical point where it seeks to link its hypothetical transmission errors to actual EEG differences that sometimes correlate with intelligence differences.