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 the University of Southern California, Harvard University, Caltech 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?

A total of 30 subjects of both genders faced a set of scenarios pitting immediate harm to one person against future certain harm to many. Six had damage to the ventromedial prefrontal cortex (VMPC), a small region behind the forehead, while 12 had brain damage elsewhere, and another 12 had no damage.

The subjects with VMPC damage stood out in their stated willingness to harm an individual a prospect that usually generates strong aversion.

Because of their brain damage, they have abnormal social emotions in real life. They lack empathy and compassion, said Ralph Adolphs, Bren Professor of Psychology and Neuroscience at Caltech.

In those circumstances most people without this specific brain damage will be torn. But these particular subjects seem to lack that conflict, said co-senior author Antonio Damasio, director of the Brain and Creativity Institute and holder of the David Dornsife Chair in Neuros
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Contact: Carl Marziali
marziali@usc.edu
213-219-6347
University of Southern California
21-Mar-2007