In our introduction, two reasons were put forward as to why ERO power measures might provide unique discriminatory information beyond that of ERP amplitude measures. For EROEVK power measures, it was argued that the temporal extent of the ERO measures across a time interval, rather than at a single time point, could account for the additional discriminatory information. The premise for this argument is that the dynamics or morphology of an ERP component might differ between groups. Our results indicate that this is not the case and any additional information contained in the evoked ERO power measures due to P3b dynamics does not significantly contribute towards group discrimination. The second reason was that in addition to evoked activity, the EROTOT power measures contains contributions of non-phase-locked activity, and this induced activity might provide additional discriminatory information beyond the ERP amplitude measures. The post hoc EROTOT power finding, although not warranted by the MANCOVA, gives a weak indication that induced θ activity might provide group discriminatory information beyond that of the ERP. This indication of a potential contribution to group discrimination of induced activity should be followed up with a more complete investigation of event-related non-phase-locked activity.
