Evoked potentials (EPs) provide a unique way of analyzing the relationship between genes and behavior. Individual differences in EPs, in response to light flashes of two intensities and pattern reversal, were studied in families from the isolated population Mechelta in the Northern Caucasus. While there were no age or sex differences in EP latency, or many age effects on amplitude, there were sex differences on the amplitude measures. Variation in the additive genetic determination of latency and amplitude measures is discussed. The largest estimates of additive genetic variation were found for the complexes of amplitude measures between the positive and negative waveforms.