Mixed-effects model results for NF learning. The dependent variable is mean amplitude (μV) of baseline-corrected trials. Feedback/transfer: condition where a feedback stimulus is (feedback) or is not (transfer) visible. Session: session number, 15 double training sessions in total. Bins: bin number, 10 bins in total. Task: performance in the deactivation (generation of positive potential shifts) versus activation tasks (generation of negative potential shifts). MPH: on constant methylphenidate medication (yes versus no). α2: within-subject residual variance. τ00, subject: between-subject variance. τ11: random slope variance. ρ01: random intercept slope correlation.