The key area of the brain is a knot of nerve cells known as the right temporo-parietal junction (RTPJ).
The researchers subjected 20 volunteers to a number of tests designed to assess their notions of right and wrong.
In one scenario participants were asked how acceptable it was for a man to let his girlfriend walk across a bridge he knew to be unsafe.
After receiving a 500 millisecond magnetic pulse to the scalp, the volunteers delivered verdicts based on outcome rather than moral principle.
If the girlfriend made it across the bridge safely, her boyfriend was not seen as having done anything wrong.
In effect, they were unable to make moral judgments that require an understanding of other people's intentions.