One of the things that distinguishes humans from animals is moral judgment, our ability to judge other people’s actions in terms of our own sense of right and wrong.
Our moral judgment feels so integral to who we are, so much a part of our personality, that it’s a bit disturbing to discover, as MIT researchers reported this week, that it can be disrupted by magnets.
Rebecca Saxe, an assistant professor of brain and cognitive sciences at MIT, has focused her research on social cognition: how we interpret other people’s thoughts. She wants to understand how the brain gives rise to things like moral judgments, belief systems and language.
The challenge, of course, is that we have no way to observe people’s thoughts and beliefs directly. Nevertheless, we do have tools with which to see which parts of the brain are active when we think about other people’s thoughts, which we do whenever we’re trying to figure out why others are behaving the way they are.
I’ve referred in many previous columns to functional magnetic resonance imaging, or fMRI, which measures blood flow, and hence activity, in various regions of the brain. Using that tool, Saxe has discovered that an area called the right temporo-parietal junction (TPJ), is highly active when we think about people’s intentions, thoughts and beliefs.
In the new study, Saxe and her fellow researchers used a non-invasive technique called transcranial magnetic stimulation (TMS) to selectively interfere with brain activity in the right TPJ: in other words, they applied a strong magnetic field to a small area of the skull. The magnetic field created weak electrical currents that made it hard for nearby brain cells to fire normally. (Fortunately, the effect is temporary.)
They ran two experiments. In one, they exposed the right TPJ of volunteers to TMS for 25 minutes, then had the volunteers take a test in which they read a series of scenarios and made moral judgments on the actions of the characters in the scenarios, using a scale of one to seven, with one being “absolutely forbidden” and seven being “absolutely permissible.”
In the second, they applied TMS in 500-millisecond bursts just at the moment when the volunteer was asked to make a moral judgment, such as how permissible it is for a man to let his girlfriend walk across a bridge he knows to be unsafe, even if she makes it across unharmed.
(That’s a common kind of scenario in morality studies, because people who have the normal capacity to infer other people’s thoughts would typically judge the man as morally wrong because something bad could have happened and he knew it, whereas those without that capacity, such as those with certain kinds of brain damage, judge his action to be morally acceptable because nothing bad actually happened.)
In both experiments, the researchers discovered that, when the right TPJ was subjected to TMS, the subjects were more likely to judge the man’s action as morally permissible. That seems to indicate that when brain activity in the right TPJ is disrupted, people are less able to interpret other’s intentions, leaving them with only the outcome on which to make their judgment.
“You think of morality as being a really high-level behaviour,” says the study’s lead author, Liane Young. “To be able to apply (a magnetic field) to a specific brain region and change people’s moral judgments is really astonishing.”
That’s not to say that the disruption completely reversed people’s moral judgments, but it definitely biased them. As Saxe points out, there’s more to moral judgment than merely understanding other people’s intentions. We also take into account their desires, previous record and any external constraints, and it’s all guided by our own concepts of loyalty, fairness and integrity.
Moral judgment, Saxe says, even though it feels like one uniform thing, is “actually a hodgepodge of competing and conflicting judgment, all of which get jumbled into what we call moral judgment.”
As the MIT researchers continue their research, I can’t help but think there’s a germ of a science fiction story here, one in which a villain uses technology to disrupt the brain activity of a law-abiding citizen, turning him into a savage, murderous animal. I even have a title: “Animal Magnetism.”
OK, maybe not.