(A) Schematic responses of feedback-related potentials with respect to RPE and UPE encoders. The upper panel represents RPE, which proposes that the feedback-related potentials should be more negative for worse-than-expected outcomes. The lower panel represents UPE, which argues that the feedback-related potentials may become more negative with the increasing deviation of expectation regardless of the outcome valence. “EV” denotes the expected value. The right side of the horizontal axis represents the higher-than-expected feedback; the left-side signals the lower-than-expected feedback. (B) Schematic of experimental procedure. The time course of one trial is designated; the feedback contingencies associated with high- and low-value shapes are illustrated.