A, Error signaling ROI in left ventral striatum, identified from the conjunction of Rc and –Ru across subjects (p < 0.001, uncorrected). B, In left striatum (circled in Figure 4A), the neural effect size for –Ru was positively correlated, across subjects, with the weight for the unchosen reward, κ, estimated from choice behavior (p = 0.018, Bonferroni corrected; r = 0.57).