Statistical comparisons between time-domain (TD) and time-frequency (TF) signal representations of the data revealed that the theta and delta TF-PCA measures together accounted for a majority of the variance in both the time-domain FRN and P300 measures. These analyses indicated that the TD measures represented a mixture of TF theta and delta activity, and that the TF theta and delta measures provided largely independent, and more parsimonious, indices of ERP activity to the primary Loss and Gain feedback outcomes, respectively.3 As illustrated by the top two line plots of Figure 2, this mixture of TF activity can be understood in terms of the changing phase of the more rapid theta oscillation (i.e., alternating positive and negative polarity). Specifically, there is an earlier negative polarity peak in the theta oscillation (maximal around 275 ms) corresponding to the FRN, followed by a subsequent positive deflection that reaches its maximum near the same time at which the P300 response reaches its peak (i.e., around 375 ms). In contrast, the delta activity component corresponding to the P300 consists of a unidirectional slow-wave that contributes
