Memory decoding trained on the explicit recognition memory task. A, Performance of memory classifiers (hits vs CRs) trained on standard recognition memory data and tested on held-out trials from the same condition (explicit memory trials, EX→EX; blue) or on trials when they were attempting to conceal their true memory state (concealed memory trials, EX→CM; green). Violin plots depict the mean AUC for ROC curves (for description of this metric, see text). Plots demonstrate that memory decoding was above chance during a standard recognition memory test (EX→EX, blue) but reduced to chance levels when participants attempted to conceal memory (EX→CM, green). AUC values are plotted for each participant's data using unique color identifiers, with lines connecting each participant's classification performance, and plot-width depicting participant density in that performance range. B, Classifiers trained and tested on each time point (2 s volume acquisition, TR) revealed similar results as in A, with above-chance decoding on standard memory trials (blue) and chance decoding on concealed memory trials (time point 4–6 s was slightly above chance). C, Maps indicating the diagnostic value that each voxel provides the classifier (importance maps) in biasing a hit choice (warm colors) or a CR choice (cool colors). Error bars in B indicate SEM. EX, Explicit memory task; CM, concealed memory task; EX→EX, classifier trained on explicit trials, tested on held-out explicit trials (4-fold cross-validation); EX→CM, classifier trained on explicit trials, tested on concealed trials.