Late components of average evoked potentials in children with different abilities to concentrate.

Three matched groups, each of seven 11-year-old children with good, average and poor ability to concentrate were selected. Evoked potentials and EEG alpha amplitude changes after visual imperative stimuli were studied in warned reaction time experiments. The children with poor ability to concentrate (compared with the other groups) showed longer latencies of the P2 component and reduced amplitudes of the P2-N2 deflection at the vertex. Similar, although attenuated, effects were found in the Fz derivation. No group effects could be established for Oz. These findings are discussed in relation to group differences in pre-stimulus negativity and alpha attenuation, as reported in a previous paper.