Moral Judgments Can Be Altered: Neuroscientists Influence People’s Moral Judgments by Disrupting Specific Brain Region

Moral Judgments Can Be Altered: Neuroscientists Influence People’s Moral Judgments by Disrupting Specific Brain Region

  9:13:00 PM    Science Lover

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MIT neuroscientists have shown they can influence people's moral judgments by disrupting a specific brain region -- a finding that helps reveal how the brain constructs morality.

In a new study, researchers disrupted activity in the right temporo-parietal junction by inducing a current in the brain using a magnetic field applied to the scalp. They found that the subjects' ability to make moral judgments that require an understanding of other people's intentions -- for example, a failed murder attempt -- was impaired. (Credit: Graphic by Christine Daniloff)

To make moral judgments about other people, we often need to infer their intentions -- an ability known as "theory of mind." For example, if a hunter shoots his friend while on a hunting trip, we need to know what the hunter was thinking: Was he secretly jealous, or did he mistake his friend for a duck?

Previous studies have shown that a brain region known as the right temporo-parietal junction (TPJ) is highly active when we think about other people's intentions, thoughts and beliefs. In the new study, the researchers disrupted activity in the right TPJ by inducing a current in the brain using a magnetic field applied to the scalp. They found that the subjects' ability to make moral judgments that require an understanding of other people's intentions -- for example, a failed murder attempt -- was impaired.

The researchers, led by Rebecca Saxe, MIT assistant professor of brain and cognitive sciences, report their findings in the Proceedings of the National Academy of Sciences.

The study offers "striking evidence" that the right TPJ, located at the brain's surface above and behind the right ear, is critical for making moral judgments, says Liane Young, lead author of the paper. It's also startling, since under normal circumstances people are very confident and consistent in these kinds of moral judgments, says Young, a postdoctoral associate in MIT's Department of Brain and Cognitive Sciences.

"You think of morality as being a really high-level behavior," she says. "To be able to apply (a magnetic field) to a specific brain region and change people's moral judgments is really astonishing."

How they did it: The researchers used a non-invasive technique known as transcranial magnetic stimulation (TMS) to selectively interfere with brain activity in the right TPJ. A magnetic field applied to a small area of the skull creates weak electric currents that impede nearby brain cells' ability to fire normally, but the effect is only temporary.

In one experiment, volunteers were exposed to TMS for 25 minutes before taking a test in which they read a series of scenarios and made moral judgments of characters' actions on a scale of 1 (absolutely forbidden) to 7 (absolutely permissible).

In a second experiment, TMS was applied in 500-milisecond bursts at the moment when the subject was asked to make a moral judgment. For example, subjects were asked to judge how permissible it is for someone to let his girlfriend walk across a bridge he knows to be unsafe, even if she ends up making it across safely. In such cases, a judgment based solely on the outcome would hold the perpetrator morally blameless, even though it appears he intended to do harm.

In both experiments, the researchers found that when the right TPJ was disrupted, subjects were more likely to judge failed attempts to harm as morally permissible. Therefore, the researchers believe that TMS interfered with subjects' ability to interpret others' intentions, forcing them to rely more on outcome information to make their judgments.

Next steps: Young is now doing a study on the role of the right TPJ in judgments of people who are morally lucky or unlucky. For example, a drunk driver who hits and kills a pedestrian is unlucky, compared to an equally drunk driver who makes it home safely, but the unlucky homicidal driver tends to be judged more morally blameworthy.

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Harmful Intent: Emotions Key to Judging Others

Harmful Intent: Emotions Key to Judging Others

  12:50:00 AM    Science Lover

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A new study from MIT neuroscientists suggests that our ability to respond appropriately to intended harms -- that is, with outrage toward the perpetrator -- is seated in a brain region associated with regulating emotions.

New research suggests that our ability to respond appropriately to intended harms -- that is, with outrage toward the perpetrator -- is seated in a brain region associated with regulating emotions. (Credit: iStockphoto/Mark Evans)

Patients with damage to this brain area, known as the ventromedial prefrontal cortex (VMPC), are unable to conjure a normal emotional response to hypothetical situations in which a person tries, but fails, to kill another person. Therefore, they judge the situation based only on the outcome, and do not hold the attempted murderer morally responsible.

The finding offers a new piece to the puzzle of how the human brain constructs morality, says Liane Young, a postdoctoral associate in MIT's Department of Brain and Cognitive Sciences and lead author of a paper describing the findings in the March 25 issue of the journal Neuron.

"We're slowly chipping away at the structure of morality," says Young. "We're not the first to show that emotions matter for morality, but this is a more precise look at how emotions matter."

How they did it: Working with researchers at the University of Southern California, led by Antonio Damasio, Young studied a group of nine patients with damage (caused by aneurisms or tumors) to the VMPC, a plum-sized area located behind and above the eyes.

Such patients have difficulty processing social emotions such as empathy or embarrassment, but "they have a perfectly intact capacity for reasoning and other cognitive functions," says Young.

The researchers gave the subjects a series of 24 hypothetical scenarios and asked for their reactions. The scenarios of most interest to the researchers were ones featuring a mismatch between the person's intention and the outcome -- either failed attempts to harm or accidental harms.

When confronted with failed attempts to harm, the patients had no problems understanding the perpetrator's intentions, but they failed to hold them morally responsible. The patients even judged attempted harms as more permissible than accidental harms (such as accidentally poisoning someone) -- a reversal of the pattern seen in normal adults.

"They can process what people are thinking and their intentions, but they just don't respond emotionally to that information," says Young. "They can read about a murder attempt and judge it as morally permissible because no harm was done."

This supports the idea that making moral judgments requires at least two processes -- a logical assessment of the intention, and an emotional reaction to it. The study also supports the theory that the emotional component is seated in the VMPC.

Next steps: Young hopes to study patients who incurred damage to the VMPC when they were younger, to see if they have the same impaired judgment. She also plans to study patient reactions to situations where the harmful attempts may be directed at the patient and therefore are more personal.

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