Gray matter volume correlations with metacognitive efficiency. A, Statistical (T) maps shown for both a standard overlay and axial “glass brain,” showing areas in which gray matter volume correlates positively with meta-d′/d′ on the visual task. B, Statistical (T) maps for positive correlation with meta-d′/d′on the memory task, for both standard overlay and axial glass brain. The significant cluster was found in the precuneus region. All images were thresholded at p < 0.001 uncorrected for display purposes, but the circled clusters (in A) and the precuneus (in B) pass small volume correction for multiple comparisons.