3.3 FRN at Fz (a positivity peaking at 282 ms corresponded to FRN at Fz, see Figure 6a)
In the feedback stage, a mixed 2 (stimulus type: probe vs. irrelevant) by 2 (feedback type: success“+4”vs. failure“-2”) by 2 (group: guilty vs. innocent) ANOVA was performed on the FRN amplitude with the first two variables as within-subject variables and the third variable as a between-subject variable. Results revealed no significant main effect of stimulus type, F (1, 58) = 0.34, p = 0.56, BFExclusion = 12.80. Unexpectedly, there was no significant two-way interaction between stimulus type and group F (1, 58) = 0.66, p = 0.42, BFExclusion = 28.22. The remaining interactions were not significant: stimulus × feedback: (F (1, 58) = 1.35, p = 0.25, BFExclusion = 22.08); feedback × group: (F (1, 34) = 0.05, p = 0.82, BFExclusion = 16.02); stimulus × feedback × group interaction: (F (1, 58) = 0.23, p = 0.63, BFExclusion = 574.78). For grand-averaged ERPs and their scalp distributions elicited by feedback stimuli, see Figures 5 and 7 .