For computation of the TFRs, the trial-averaged ERP waveform was first subtracted from each single trial data before being transformed to the time-frequency domain utilizing the ST or STFT, resulting in a complex-valued TFR for each trial. The absolute power for each single-trial TFR was then calculated by taking the square of the magnitude of the complex-valued TFR for each trial and these were then averaged across all trials to produce the resultant TFR. This method of computing the event-related TFR produces a time-frequency distribution of the non-phase-locked power in the event-related trials, and is similar to the time-domain inter-trial variance method introduced by Kalcher and Pfurtscheller (1995) that produces a time course of non-phase-locked power within a predefined frequency band by first removing contributions of the phase-locked activity in this band. In the current study, the event-related TFRs produced in this way are termed even-related non-phase-locked TFRs or ERONPL TFRs to differentiate them from the event-related evoked TFRs (EROEVK TFRs) and event-related total TFRs (EROTOT TFRs) quantified in the previously studies (Andrew and Fein, In Press; Jones et al.,
