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Neuroscientists use magnetism to fool our moral compass

March 31, 2010 | 10:51 am

Neuroscientists have marched forward by many means in their understanding of how the brain and its component parts work. They have long studied people with injuries to certain parts of their brains and, by seeing how the behavior of those individuals changes, have inferred the role that the damaged part of the brain plays. In more recent years, functional magnetic resonance imaging and electro-encephalograms (those electrical wires you see attached to babies' bald pates in pictures) have helped researchers divine the roles of certain brain regions by "seeing" blood flow or metabolic activity in those regions during certain tasks.

But there's also a little known and somewhat low-tech gadget that can have surprising powers of revelation. It's called transcranial magnetic stimulation, in which a small device that emits a powerful but narrow-spectrum magnetic charge is passed over a region of the brain. It won't penetrate very far, but the result is that the cells in that region of the brain are briefly scrambled: For a few minutes, they go silent or misfire. (Neuroscientists have been known to have a bit of fun with this gadget.)

In the neuroscience lab of MIT researcher Rebecca Saxe, the role of the right temporoparietal junction -- an area toward the back of your head, a couple of inches above your right ear -- is an area of particular interest. This area has long been thought to play a role in how we interpret the actions and motives of the people around us -- a largely-human talent called "theory of mind."

In a recent study using transcranial magnetic stimulation, researchers in Saxe's lab have found that the right temporoparietal junction -- and our ability to infer other people's thoughts and motives -- may be important in how we make and act on moral and ethical judgments.

In a pair of experiments published in this week's issue of the Proceedings of the National Academy of Sciences, MIT researchers passed a transcranial magnetic stimulator over the right temporoparietal junction, in one case for 25 minutes while the study participants read a series of scenarios and decided how they should behave, and in the second experiment, briefly, while participants were asked to make a complex moral judgment. In both experiments, researchers set up the moral conundrums so that the participants could make a dangerous or immoral decision (such as driving drunk) but not have any moral consequences (such as an accident ensuing).

With their right temporoparietal junctions scrambled, participants seemed unable to recognize an action as wrong unless it led to harm -- a moral judgment that virtually all could make easily when their brains were not being magnetically scrambled. It seems that when unable to infer the motives and actions of another, they had to rely only on outcomes to tell them if their own actions were ethical.

The implications for human behavior are potentially far-reaching: Unless we can understand what's on other people's minds, we may be hampered in understanding how best to live cooperatively (and ethically) with others. And then there's a take-home message for each of us: If someone you know seems to behave without moral bearings, you might try looking for a transcranial magnetic stimulator hidden with the remote control in the folds of his or her couch. Or you might infer that his or her powers of "theory of mind" need a bit of exercise.

-- Melissa Healy

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