Abstract Past studies relating electrical brain activity to measures of intelligence have shown widely disparate results. More recently, Blinkhorn & Hendrickson ( Nature, 295, 596–597, 1982) and Hendrickson (Parts I and II. In Eysenck, H.J. (Ed.), A model for intelligence. New York, Springer, 1982) have reported high correlations between their AEP measure, termed ‘string length’, and psychometric IQ but few studies have satisfactorily replicated these results. The present study examined the relationship between string length and IQ among 20 first year psychology students and found moderate to high correlations (up to 0.86). It also found that the magnitude of these correlations was sensitive to temporal events occurring within the AEP waveform and an analysis of components within the first 250 msec after stimulus onset demonstrated that the AEP waveforms of subjects with high verbal IQ (VIQ) contained significantly more ‘early’ components than those of low VIQ subjects.