Unfeeling moral choices traced to damaged frontal lobes

Consider the following scenario: Someone you know has AIDS and plans to infect others, some of whom will die. Your only options are to let it happen or to kill the person. Do you pull the trigger?

Most people waver or say they could not, even if they agree that in theory they should. But according to a new study in the journal Nature, subjects with damage to a part of the frontal lobe make a less personal calculation. The logical choice, they say, is to sacrifice one life to save many.

Conducted by researchers at Harvard University, the University of Southern California (USC), the California Institute of Technology, and the University of Iowa, the study shows that emotion plays an important role in scenarios that pose a moral dilemma. If certain emotions are blocked, we make decisions that — right or wrong — seem unnaturally cold.

The scenarios in the study are extreme, but the core dilemma is not: Should one confront a co-worker, challenge a neighbor, or scold a loved one in the interest of the greater good?