(A) Psychophysiological interactions (PPI) analyses. The PPI used the right lateral FPC as a seed (sphere of diameter = 10 mm centered at [x,y,z] = [42,44,19]). The functional connectivity between right FPC and dACC increased when group size increased (P < 0.05, family-wise error [FWE] corrected within small volume correction [SVC]). Error bars represent the standard error of the mean (SEM) (**, P < 0.001). (B) Between-subject regression analysis considering the individual difference in the relative credibility of social information (Δσ) as a covariate for the modulation of connectivity between dACC-FPC when presented with social information of the large versus the small group (P < 0.05, FWE corrected within SVC). The scatter plot was not used for statistical inference (which is carried out in the SPM framework). It is shown solely for illustrative purposes. The functional MRI (fMRI) data can be found in http://neurovault.org/collections/2503/. The data underlying this figure can be found in S1 Data.