A) Group PSTH of all MS neurons, pooled according to their preferred and non-preferred stimulus (Pref and NP, respectively). Tuning preference is defined according to ground truth. Note that during error trials, neurons signal according to their non-preferred stimulus (the choice). Also note modulation by confidence only for the preferred, but not non-preferred, trials. B-C) Single-trial analysis confirms choice coding during error trials (Error non-preferred is significantly larger than error preferred p=9e-6; high vs. low confidence p=5e-5). D) Choice (CP) vs. memory (MP) probability for all neurons. E) CP is significantly larger than MP for both new>old (p=5.9e-5, red) and old>new (p=0.008, blue) MS neurons. F) Time-course of CP. G) CP varies as a function of confidence, with more reliable signaling for high confidence responses (1×3 repeated measure ANOVA, F=19.8, p=7.19e-9, n=166). See also Figure S5.