Individual differences in the anterior insula are associated with the likelihood of financially helping versus harming others.

The neural basis of individual differences in positive and negative social decisions and behaviors in healthy populations is yet undetermined. Recent work has focused on the potential role of the anterior insula in guiding social and nonsocial decision making, but the specific nature of its activation during such decision making remains unclear. To identify the neural regions mediating individual differences in helpful and harmful decisions and to assess the nature of insula activation during such decisions, in the present study we used a novel fMRI task featuring intentional and unintentional decisions to financially harm or help persons in need. Based on a whole-brain, unbiased approach, our findings indicate that individual differences in dorsal anterior insula, anterior cingulate cortex (ACC), and right temporo-parietal junction activation are associated with behavioral tendencies to financially harm or help another. Furthermore, activity in the dorsal anterior insula and ACC was greatest during unintended outcomes, whether these were gains or losses for a charity or for oneself, supporting models of the role of these regions in salience prediction error signaling. Together, the results suggest that individual differences in risk anticipation, as reflected in the dorsal anterior insula and dorsal ACC, guide social decisions to refrain from harming others.