To ensure that between-amplifier comparisons were valid, data from control participants recorded on both amplifier systems (NuAmps, SynAmps2) were examined and revealed no differences associated with the different acquisition amplifiers. Additionally, a within-amplifier analysis, using only the participants whose data were collected using the NuAmps amplifier, replicated ERP results reported in Fein and Chang (2006) that were produced from the combined data acquired with both amplifiers.
