We used two different sets of stimuli, facial stimuli in the social condition and fruit stimuli in the non-social conditions. We tested whether observed differences between conditions can be accounted for by low-level differences such as attention or differences in the visual distinctiveness of one stimulus set compared to the other stimuli set. (a) First, we used the existing univariate analysis (exploratory MRI whole-brain analysis, see Methods) to test whether there were significant neural activation differences between conditions that we are not accounting for with the regressors of interest relating to the interval setting at the current trial and the interval setting on the previous trial (see Methods for detailed description of regressors included into the fMRI-general linear model [GLM]). Variance in neural activity that is unrelated to these regressors but which is consistently related to one of the two conditions – social or non-social – should then be captured in the constant of a GLM model. For example, if there are attentional differences between conditions that are not explained by the interval setting in the current and past trial, then these attentional differences would be captured in the constant. There were no meaningful activation patterns that covaried with the constant that differed between conditions in either attentional areas (e.g., inferior parietla lobule: IPL), or in brain areas that were the focus of the study (dorsomedial prefrontal cortex [dmPFC] and posterior temporoparietal junction [pTPJ]). These results were replicated in a region-of-interest (ROI) approach based on dmPFC (confidence constant; paired t-test social vs. non-social: t(23) = 0.06, p = 0.96, [−36.7, 38.75]), bilateral TPJ (confidence constant; paired t-test social vs. non-social: t(23) = −0.06, p = 0.95, [−31, 29]), and bilateral IPL (confidence constant; paired t-test social vs. non-social: t(23) = −0.58, p = 0.57, [−30.3 17.1]). We used the same coordinates as mentioned elsewhere when defining ROIs for dmPFC and pTPJ and used an anatomical mask of ‘IPLD’ (Mars et al., 2011). (b) Next, we tested whether the visual distinctiveness of one stimulus set was different to the visual distinctiveness of the other stimuli set. We used representational similarity analysis (RSA) to compare the Exemplar Discriminability Index (EDI) between conditions in early visual cortex: we compared the dissimilarity of neural activation related to the presentation of an identical stimulus across trials (diagonal in RSA matrix) with the dissimilarity in neural activation between different stimuli across trials (off-diagonal in RSA matrix). If the distinctiveness within one stimulus set is different compared to the distinctivness in the other stimulus set, then we would expect a significant difference in the EDI measure between social and non-social conditions (see Figure 4g for schematic illustration). Hence, if there is a difference in the visual distinctiveness between social and non-social conditions, then this difference should result in different EDI values for both conditions – hence, visual distinctiveness between the stimuli set can be tested by comparing the EDI values between conditions within the early visual processing. We used a Harvard-cortical ROI mask based on bilateral V1 and showed that there was no significant difference in EDI between conditions (EDI paired sample t-test: t(23) = −0.16, p = 0.87, 95% confidence interval [CI] [−6.7 5.7]). Hence, these control analyses suggest that differences between social and non-social conditions are unlikely to arise because of differences in low-level processes reflecting the visual features between stimuli sets or attentional processes. Instead, differences between social and non-social conditions reported in dmPFC and pTPJ in Figure 4h are likely to be related to differences in social and non-social learning processes. (c, d) We additionally conducted a whole-brain searchlight analysis, for details refer to Figure 4—figure supplement 3. (c) We extracted EDI pattern activation in the previously defined V1 ROI in a whole-brain searchlight analysis and demonstrate that again, pattern activation encoded EDI for both social and non-social conditions. (d) Results of the whole-brain searchlight analysis showing a conjunction across both social and non-social conditions demonstrating pattern activation encoding identity averaged across both social and non-social conditions in visual areas.