We hypothesized that complex wavelet frequency decomposition would show that EEG responses to non-rewards versus rewards would be associated with enhanced power and phase coherence in the theta frequency band. Given that a large portion of the feedback related negativity is attributable to activity in the theta band (Cavanagh, Eisenberg, Guitart-Masip, Huys, & Frank, 2013; Cavanagh et al., 2010; Cohen et al., 2007) and several age comparison studies have found that the FRN (positive and negative outcome) is generally larger in children, decreasing in amplitude across adolescence, we also expected to see a decrease in post-feedback theta power across the age groups in our sample. However, we also acknowledge that recent neuroimaging work suggests increased sensitivity to rewards for some adolescents (Cohen et al., 2010; Galvan, Hare, Voss, Glover, & Casey, 2007). It is surprising that the published studies of the FRN comparing adolescence to other developmental periods have failed to identify reward-related EEG neural correlates unique to adolescence. One possibility is that the signal averaging approach obscures important aspects of feedback processing that may emerge with an event-related oscillatory approach. Thus, we remain open to the possibility that oscillatory patterns do not follow a linear pattern across development.
