University of Illinois, Urbana-Champaign and California Institute of Technology researchers used fMRI scans to observe the brain making morally charged tradeoffs between two different motivations.

Volunteers were scanned as they decided between pairs of difficult options on how to distribute scarce meals to children at an orphanage. The choices reflected a balance between avoiding inequity (one child receiving less food than others) and maximizing the common good (the count of meals available to all children).

The researchers found that different areas of the brain tracked the two motivations. The insula (a region associated with processing emotion) became more active when the volunteers had to consider inequitable distributions. Another region, the putamen, seemed to track the common good (maximizing total meals).