Although many researchers (e.g., Nieuwenhuis et al. [19] and Holroyd et al. [46]) uphold the view that ORN and ERN are manifestations of the same underlying cognitive and neural processes, others (e.g., Gehring & Willoughby [15]) maintain that ORN could be a separate component independent of the error/correct dimension and may reflect the emotional/motivational aspects of reward processing. Gehring & Willoughby [47] further differentiated the ERN and ORN (MFN) using wavelet transform; they report that the scalp topography of the theta band (4-7 Hz) of the ORN is more right lateralized and anterior in its scalp distribution than is the ERN. Although several hypotheses, such as the mismatch hypothesis [48], the conflict hypothesis [49], the inhibition hypothesis [50] and the reinforcement learning hypothesis [51] have been proposed to explain the functional significance of the ERN (cf. Falkenstein [30]), our results are perhaps more in agreement with the reinforcement learning hypothesis (gain against loss) by differentiating ORN features specific to ‘loss’ as against ‘gain’. As shown in Fig. 5, the distinction of gain vs. loss (valence) is processed earlier (200-400 ms)
