The neural correlates of moral comparison.

Moral comparison supports the moral judgment that then evaluates social behaviors and restrains social interactions. However, previous studies have not investigated what neural networks support the process of moral comparison. The present study examined neural networks of moral and physical size comparisons using a distance paradigm and functional magnetic resonance imaging. In the experiment, participants judged which picture/sentence presented a more moral scenario in the moral comparison run or which picture/sentence had a larger physical size in the physical comparison run. Results demonstrated that both moral and physical comparisons induced a distance effect-participants' responses were faster for high than low distance comparisons. Moreover, moral and physical comparisons recruited similar neural networks, including the bilateral dorsomedial prefrontal cortex, bilateral intraparietal sulcus, and bilateral insula. Interestingly, compared with physical size comparisons, moral comparisons elicited stronger activity in the bilateral precuneus, bilateral angular gyrus, and bilateral superior frontal gyrus. Meanwhile, compared with moral comparisons, physical size comparisons elicited stronger activity in the right inferior parietal lobule. Together, these results suggest that the neural substrates of moral and physical comparisons not only share the frontoparietal network but also rely on specific neural underpinnings, depending on the specific comparison recruited.