Event Related Potentials (ERPs). The grand averages of event related potentials (ERPs) for auditory (black traces), somatosensory (red traces) and simultaneous auditory and somatosensory stimuli (green traces) are shown for a sample of 21 children. The ERPs are shown at midline electrode sites (Fz, Cz and Pz) and central/post-central electrode sites (C3, CP5, C4 and CP6). The P100, N100 and P200 ERP amplitude peaks are labeled at electrode site Cz. The placement of the electrode sites are indicated in a top view schematic in the upper left corner.